Rodger I Thompson

Interests

Teaching

fundamental astrophysics, atomic and molecular spectra, stellar structure and evolution

Research

Theory and observation of fundamental constants in the early universe, cosmology, galaxy evolution, infrared imaging and spectroscopy

Courses

Scholarly Contributions

Journals/Publications

• Thompson, R. I. (2019). Beta Function Quintessence Cosmological Parameters and Fundamental Constants II: Exponential and Logarithmic Dark Energy Potentials. Monthly Notices of the Royal Astronomical Society, 482, 5448-5458.
• Thompson, R. I. (2019). Beta function quintessence cosmological parameters and fundamental constants II. Logarithmic and Exponential dark energy potentials.. Monthly Notices of the Royal Astronomical Society, 482, 11.
• Thompson, R. I. (2019). Testing bound dark energy with cosmological parameter and fundamental constant evolution. Monthly Notices of the Royal Astronomical Society, 490, 4778-4785.
• Thompson, R. I. (2018). Beta Function Quintessence Cosmological Parameters and Fundamental Constants I: Power and Inverse Power Law Dark Energy Potentials. Monthly Notices of the Royal Astronomical Society, 13.
• Thompson, R. I. (2018). Beta Function Quintessence Cosmological Parameters and Fundamental Constants I: Power and Inverse Power Law Dark Energy Potentials. Monthly Notices of the Royal Astronomical Society, 477, 4104-4115.
• Thompson, R. I. (2016). Fundamental Constants as Monitors of the Universe. Proceedings of the 14th Grossmann Conference.
• Thompson, R. I. (2017). Fundamental Constant Observational Bounds on the Variability of the QCD Scale. Monthly Notices of the Royal Astronomical Society, 467, 4558-4564.
• Thompson, R. I. (2017). Fundamental Constant Observational Bounds ont Variability of the QCD Scale. Monthly Notices of the Royal Astronomical Society, TBD(TBD), 8.
• Thompson, R. I. (2017). The Relation between Fundamental Constants and Particle Physics Parameters. Universe, 3(6), 8. doi:doi:10.3390
• Jorgenson, R. A., Murphy, M. T., Thompson, R. I., & Carswell, R. F. (2014). The Magellan uniform survey of damped Lyman Alpha Sustems I. MNRAS, 435, 482.
• Jorgenson, R. A., Murphy, M. T., Thompson, R. I., & Carswell, R. F. (2014). The Magellan uniform survey of damped Lyman Alpha Systems II. MNRAS, 443, 2783.
• Thompson, R. I. (2014). Confronting cosmology and new physics with fundamental constants. Memorie della Societa Astronomica Italiana, 85, 20.
• Thompson, R. I. (2014). The Magellan uniform survey of damped Lyman Alpha Systems II. Monthly Notices of the Royal Astronomical Society, 443, 2783.
• Jorgenson, R. A., Murphy, M. T., & Thompson, R. (2013). The Magellan uniform survey of damped Lyman α systems - I. Cosmic metallicity evolution. Monthly Notices of the Royal Astronomical Society, 435(1), 482-501.
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  Abstract: We present the chemical abundance measurements of the first large, medium-resolution, uniformly selected damped Lyman α system (DLA) survey. The sample contains 99 DLAs towards 89 quasars selected from the SDSS DR5DLA sample in a uniform way. We analyse the metallicities and kinematic diagnostics, including the velocity width of 90 per cent of the optical depth,δν90, and the equivalent widths of the Si II λ1526 (Wλ1526), CIV λ1548 and MgII λ2796 transitions. To avoid strong line-saturation effects on the metallicities measured in medium-resolution spectra (FWHM ~ 71 km s-1), we derived metallicities from metal transitions which absorbed at most 35 per cent of the quasarcontinuum flux. We find the evolution in cosmic mean metallicity of the sample, (Z) = (-0.04 ± 0.13)z - (1.06 ± 0.36), consistent with no evolution overthe redshift range z ~ [2.2, 4.4], but note that the majority of our samplefalls at z ~ [2.2, 3.5]. The apparent lack of metallicity evolution with redshift is also seen in a lack of evolution in the median δν90 and Wλ1526 values. While this result may seem to conflict with other large surveys that have detected significant metallicity evolution,such as Rafelski et al. who found (Z) = (-0.22 ± 0.03)z - (0.65 ± 0.09) over z ~ [0, 5], several tests show that these surveys are not inconsistent with our new result. However, over the smaller redshift range covered by our uniformly selected sample, the true evolution of the cosmic mean metallicity in DLAs may be somewhat flatter than the Rafelski et al. estimate. © 2013 The Authors, Published by Oxford University Press on behalf of the Royal Astronomical Society.
• Thompson, R. I. (2013). A new substantive proton to electron mass ratio constraint on rolling scalar field cosmologies. Monthly Notices of the Royal Astronomical Society, 431(3), 2576-2579.
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  Abstract: New PKS 1830-211 radio frequency observations of methanol at a redshift of 0.885 82 have established the most stringent limits on changes in the proton to electron mass ratio μ to date. The observations place the limit of δμ/μ ≤ (0.0 ± 1.0) × 10-7 which is approximately a factor of 4 lower than the previous lowest limit at a redshift of 0.6742. This stringent limit at a look back time of roughly half the age of the Universe has profound implications for rolling scalar field cosmologies and the new physics that they require. Many of these cosmologies invoke a scalar field φ that is also coupled to the electromagnetic field causing the values of the fundamental constants, μ and the fine structure constant a to roll with time. If the lowest expected value of the coupling to μ, ζμ, is invoked, the new limit requires a limit on the dark energy equation of state parameter w such that (w + 1) ≤ 0.001 at a redshift of 0.885 82. This eliminates almost all of the expected parameter space for such cosmologies and new physics that have a coupling to the electromagnetic field. In these cases, the limit requires that w must be extremely close to -1 for the last half of the age of the universe or that the coupling of the rolling scalar field to μ and the electromagnetic field be significantly below or at the limit of its expected range. The new observations solidify the role of fundamental constants in providing probes of the possible cosmologies and new physics to explain the acceleration of the expansion of the universe. © 2013 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.
• Thompson, R. I., Martins, C. J., & Vielzeuf, P. E. (2013). Constraining cosmologies with fundamental constants - I. Quintessence and K-essence. Monthly Notices of the Royal Astronomical Society, 428(3), 2232-2240.
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  Abstract: Many cosmological models invoke rolling scalar fields to account for the observed acceleration of the expansion of the Universe. These theories generally include a potential V(φ) which is a function of the scalar field φ. Although V(φ) can be represented by a very diverse set of functions, recent work has shown that under some conditions, such as the slow-roll conditions, the equation of state parameter w is either independent of the form of V(φ) or part of family of solutions with only a few parameters. In realistic models of this type the scalar field couples to other sectors of the model leading to possibly observable changes in the fundamental constants such as the fine structure constant α and the proton to electron mass ratio μ. Although the current situation on a possible variance of α is complicated, there are firm limitations on the variance of μ in the early universe. This paper explores the limits this puts on the validity of various cosmologies that invoke rolling scalar fields. We find that the limit on the variation of μ puts significant constraints on the product of a cosmological parameter w + 1 and a new physics parameter ζ 2μ, the coupling constant between μ and the rolling scalar field. Even when the cosmologies are restricted to very slow roll conditions either the value of ζ μ must be at the lower end of or less than its expected values or the value of w + 1 must be restricted to values vanishingly close to 0. This implies that either the rolling scalar field is very weakly coupled to the electromagnetic field, small ζ μ, very weakly coupled to gravity, (w + 1) ≈ 0 or both. These results stress that adherence to the measured invariance in μ is a very significant test of the validity of any proposed cosmology and any new physics it requires. The limits on the variation of μ also produces a significant tension with the reported changes in the value of α. © 2012 The Authors.
• Aad, G., Abbott, B., Abdallah, J., Abdelalim, A. A., Abdesselam, A., Abdinov, O., Abi, B., Abolins, M., Abramowicz, H., Abreu, H., & al., e. (2012). Search for decays of stopped, long-lived particles from 7 TeV pp collisions with the ATLAS detector. European Physical Journal C, 72, 1965.
• Thompson, R. I. (2012). Constraints on quintessence and new physics from fundamental constants. Monthly Notices of the Royal Astronomical Society: Letters, 422(1), L67-L71.
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  Abstract: Changes in the values of the fundamental constants μ, the proton to electron mass ratio, and α, the fine structure constant due to rolling scalar fields, have been discussed both in the context of cosmology and in newphysics such as supersymmetry models. This Letter examines the changes in these fundamental constants in a particular example of such fields, freezing and thawing slow roll quintessence. Constraints are placed on the product of a cosmological quantity, w, the equation of state parameter, and the square of the coupling constants for μ and α with the field, ζ x (x = μ, α), using the existing observational limits on the values of Δx/x. Various examples of slow-rolling quintessence models are used to further quantify the constraints. Some of the examples appear to be rejected by the existing data which strongly suggest that conformation to the values of the fundamental constants in the early universe is a standard test that should be applied to any cosmological model or suggested new physics. © 2012 The Author Monthly Notices of the Royal Astronomical Society © 2012 RAS.
• Vanzi, L., Cresci, G., Sauvage, M., & Thompson, R. (2011). Integral field spectroscopy in the near infrared of NGC 3125-A and SBS 0335-052. Astronomy and Astrophysics, 534.
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  Abstract: We present integral field spectroscopy in the near infrared of the nearby dwarf starburst galaxy NGC 3125-A and of the low metallicity dwarf galaxy SBS 0335-052. The use of adaptive optics in the observations produces sub-arcsecond angular resolution. We pinpoint the star forming cores of both galaxies, identify relevant ISM components such as dust, photo ionized gas, shock excited gas and molecular gas. We relate these components to the large scale star formation process of the galaxies. In particular we find the emission of the near infrared lines of H2 and especially [FeII] does not coincide with the HII region in NGC 3125. We have the first clear detection of [FeII] in SBS 0335-052. © 2011 ESO.
• Thompson, R. I., Bechtold, J., Black, J. H., & Martins, C. J. (2009). Alternative data reduction procedures for UVES: Wavelength calibration and spectrum addition. New Astronomy, 14(4), 379-390.
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  Abstract: This paper addresses alternative procedures to the ESO supplied pipeline procedures for the reduction of UVES spectra of two quasar spectra to determine the value of the fundamental constant μ = Mp / Me at early times in the universe. The procedures utilize intermediate product images and spectra produced by the pipeline with alternative wavelength calibration and spectrum addition methods. Spectroscopic studies that require extreme wavelength precision need customized wavelength calibration procedures beyond that usually supplied by the standard data reduction pipelines. An example of such studies is the measurement of the values of the fundamental constants at early times in the universe. This article describes a wavelength calibration procedure for the UV-visual Echelle spectrometer on the very large telescope, however, it can be extended to other spectrometers as well. The procedure described here provides relative wavelength precision of better than 3 × 10- 7 for the long-slit Thorium-Argon calibration lamp exposures. The gain in precision over the pipeline wavelength calibration is almost entirely due to a more exclusive selection of Th/Ar calibration lines. © 2008 Elsevier B.V. All rights reserved.
• Thompson, R. I., Bechtold, J., Black, J. H., Eisenstein, D., Fan, X., Kennicutt, R. C., Martins, C., Prochaska, J. X., & Shirley, Y. L. (2009). An observational determination of the proton to electron mass ratio in the early universe. Astrophysical Journal Letters, 703(2), 1648-1662.
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  Abstract: In an effort to resolve the discrepancy between two measurements of the fundamental constant μ, the proton to electron mass ratio, at early times in the universe we reanalyze the same data used in the earlier studies. Our analysis of the molecular hydrogen absorption lines in archival Very Large Telescope/Ultraviolet and Visible Echelle Spectrometer (UVES) spectra of the damped Lyman alpha systems in the quasi-stellar objects Q0347-383 and Q0405-443 yields a combined measurement of a Δμ/μ value of (-7 8) × 10-6, consistent with no change in the value of μ over a time span of 11.5 Gyr. Here, we define Δμ as (μz - μ0) where μz is the value of μ at a redshift of z and μ0 is the present-day value. Our null result is consistent with the recent measurements of King etal., Δμ/μ = (2.6 3.0) × 10-6, and inconsistent with the positive detection of a change in μ by Reinhold etal. Both of the previous studies and this study are based on the same data but with differing analysis methods. Improvements in the wavelength calibration over the UVES pipeline calibration is a key element in both of the null results. This leads to the conclusion that the fundamental constant μ is unchanged to an accuracy of 10-5 over the last 80% of the age of the universe, well into the matter dominated epoch. This limit provides constraints on models of dark energy that invoke rolling scalar fields and also limits the parameter space of supersymmetric or string theory models of physics. New instruments, both planned and under construction, will provide opportunities to greatly improve the accuracy of these measurements. © 2009 The American Astronomical Society. All rights reserved.
• Thompson, R. I., Sauvage, M., Kennicutt, R. C., Engelbracht, C., Vanzi, L., & Schneider, G. (2009). Super star clusters in SBS0335-052E. Astrophysical Journal, 691(2), 1068-1078.
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  Abstract: As one of the lowest metallicity star-forming galaxies, with a nucleus of several super star clusters (SSCs), SBS0335-052E is the subject of substantial current study. We present new insights on this galaxy based on new and archival high spatial resolution NICMOS and attitude control system images. We provide new measurements and limits on the size of several of the SSCs. The images have sufficient resolution to divide the star formation into compact regions and newly discovered extended regions, indicating a bimodal form of star formation. The star formation regions are dated via the equivalent width of the Paα emission and we find that two of the extended regions of star formation are less than 10 million years old. Our previous finding that stellar winds confine the photo-ionizing flux to small regions around individual stars is consistent with the new observations. This may allow planet formation in what would traditionally be considered a harsh environment and has implications for the number of planets around globular cluster stars. In addition, the images pinpoint the regions of H2 emission as located in, but not at the center of, the two star-forming super star clusters, S1 and S2. © 2009. The American Astronomical Society. All rights reserved..
• Thompson, R. I. (2008). A molecular probe of dark energy. ESO Astrophysics Symposia, 2008, 113-116.
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  Abstract: Many theories of dark energy invoke rolling scaler fields which in turn predict time variable fundamental constants such as the ratio of electron to proton mass μ. Molecular energy levels are sensitive to μ with the electronic, vibrational and rotational levels affected each in a different manner depending on their quantum numbers. High redshift damped Lyman alpha clouds with molecular hydrogen offer an excellent opportunity to search for this possible variation. New, very accurate, laboratory measurements of the wavelengths of the Lyman and Werner transitions make it now possible to check whether the small variations in wavelength due to a time varying value of μ, are present. © 2008 Springer-Verlag Berlin Heidelberg.
• Thompson, R. I. (2008). The near infrared background: resolved and identified. AIP Conference Proceedings, 990, 132-135.
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  Abstract: The magnitude and nature of the Near Infrared Background has received a great deal of recent attention. There have been claims of an excess in the background at 1.4 microns and for evidence of high redshift sources, possibly the ones that participated in the reionization of the universe. This work indicates that there is no excess in the background over the normal galaxies observed in the near infrared. In addition, residual spatial fluctuations in the near infrared background after the subtraction of all known sources have also been attributed to high redshift sources. Our analysis of the color of the residual fluctuations indicates that the fluctuations come from faint low redshift sources below the detection limit of the NICMOS and Spitzer observations. The basic conclusion is that the nature of the near infrared background does not require the presence of very high redshift sources to account for its currently observed properties, although a faint, yet undetected, high redshift component is almost certainly there. © 2008 American Institute of Physics.
• Thompson, R. I., Bechtold, J., Eisenstein, D., Fan, X., Arnett, D., Martins, C., Kennicutt, R., & Black, J. (2008). A molecular probe of dark energy. Advances in Space Research, 42(3), 596-598.
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  Abstract: Many theoretical models of dark energy invoke rolling scaler fields which in turn predict time varying values of the fundamental constants. Establishing the value of the fundamental constants at various times in the universe can probe and test the various dark energy theories. One of the constants that is predicted to vary is the ratio of the electron to proton mass μ. It was established early on that molecular spectra are sensitive to the value of μ and can be used as probes of that value. This article describes the use of the spectrum of molecular hydrogen in high redshift Damped Lyman Alpha systems (DLAs) as a sensitive probe of the time evolution of μ. © 2007 COSPAR.
• Thompson, R. I., Eisenstein, D., Fan, X., Rieke, M., & Kennicutt, R. C. (2007). Constraints on the cosmic near-infrared background excess from nicmos deep field observations. Astrophysical Journal, 657(2 I), 669-680.
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  Abstract: NICMOS observations of the resolved object fluxes in the Hubble Deep Field-North and the Hubble Ultra Deep Field are significantly below the fluxes attributed to a 1.4-1.8 μm near-infrared background excess (NIRBE) from previous low spatial resolution NIRS measurements. Tests placing sources in the NICMOS image with fluxes sufficient to account for the NIRBE indicate that the NIRBE flux must be either flat on scales greater than 100″ or clumped on scales of several arcminutes to avoid detection in the NICMOS image. A fluctuation analysis of the new NICMOS data shows a fluctuation spectrum consistent with that found at the same wavelength in deep 2MASS calibration images. The fluctuation analysis shows that the majority of the fluctuation power comes from resolved galaxies at redshifts of 1.5 and less and that the fluctuations observed in the earlier deep 2MASS observations can be completely accounted for with normal low-redshift galaxies. Neither the NICMOS direct flux measurements nor the fluctuation analysis require an additional component of near-infrared flux other than the flux from normal resolved galaxies in the redshift range between 0 and 7. The residual fluctuations in the angular range between 1″ and 10″ is 1-2 nW m-2 sr-1, which is at or above several predictions of fluctuations from high redshift Population III objects, but inconsistent with attributing the entire NIRBE to high-redshift galaxies. © 2007. The American Astronomical Society. All rights reserved.
• Thompson, R. I., Eisenstein, D., Fan, X., Rieke, M., & Kennicutt, R. C. (2007). Evidence for a z < 8 origin of the source-subtracted near-infrared background. Astrophysical Journal, 666(2 I), 658-662.
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  Abstract: This paper extends our previous fluctuation analysis of the near-infrared background at 1.6 μm to the 1.1 μm (F 110W) image of the Hubble Ultra Deep Field. When all detectable sources are removed, the ratio of fluctuation power in the two images is consistent with the ratio expected for faint, z < 8, sources, and is inconsistent with the expected ratio for galaxies with z > 8. We also use numerically redshifted model galaxy spectral energy distributions for 50 and 10 Myr old galaxies to predict the expected fluctuation power at 3.6 and 4.5 μm to compare with recent Spitzer observations. The predicted fluctuation power for galaxies at z = 0-12 matches the observed Spitzer fluctuation power, while the predicted power for z > 13 galaxies is much higher than the observed values. As was found in the 1.6 μm (F160W) analysis, the fluctuation power in the source-subtracted F110W image is 2 orders of magnitude below the power in the image with all sources present. This leads to the conclusion that the 0.8-1.8 μm near-infrared background is due to resolved galaxies in the redshift range z < 8, with the majority of power in the redshift range of 0.5-1.5. © 2007. The American Astronomical Society. All rights reserved.
• Thompson, R., Eisenstein, D., Fan, X., Rieke, M., & Kennicutt, R. (2007). NICMOS measurements of the near-infrared background. Nuovo Cimento della Societa Italiana di Fisica B, 122(9-11), 941-946.
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  Abstract: This paper addresses the nature of the near-infrared background. We investigate whether there is an excess background at 1.4 microns, what is the source of the near-infrared background and whether that background after the subtraction of all known sources contains the signature of high-redshift objects (Z > 10). Based on NICMOS observations in the Hubble Ultra Deep Field and the Northern Hubble Deep Field we find that there is no excess in the background at 1.4 microns and that the claimed excess is due to inaccurate models of the zodiacal background. We find that the near-infrared background is now spatially resolved and is dominated by galaxies in the redshift range between 0.5 and 1.5. We find no signature than can be attributed to high-redshift sources after subtraction of all known sources either in the residual background or in the fluctuations of the residual background. We show that the color of the fluctuations from both NICMOS and Spitzer observations are consistent with low-redshift objects and inconsistent with objects at redshifts greater than 10. It is most likely that the residual fluctuation power after source subtraction is due to the outer regions of low-redshift galaxies that are below the source detection limit and therefore not removed during the source subtraction. © Società Italiana di Fisica.
• Thompson, R. I., Eisenstein, D., Fan, X., Dickinson, M., Illingworth, G., & Kennicutt Jr., R. C. (2006). Star formation history of the hubble ultra deep field: Comparison with the hubble deep field-north. Astrophysical Journal Letters, 647(2 I), 787-798.
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  Abstract: We use the NICMOS Treasury and ACS HUDF images to measure the extinction-corrected star formation history for 4681 galaxies in the region common to both images using the star formation rate distribution function and other techniques similar to those employed with the NICMOS and WFPC2 images in the HDFN. Unlike the HDFN, the NICMOS region of the HUDF appears to lack highly luminous and high star formation rate galaxies at redshifts beyond 3. The HUDF provides a region that is completely uncorrelated to the HDFN and therefore provides an independent measure of the star formation history of the universe. The combined HUDF and HDFN star formation rates show an average rate of 0.2 M⊙ yr-1 Mpc-3. The average SFR of the combined fields at z = 1-3 is 0.29 M⊙ yr-1 Mpc -3, while the average at z = 4-6 is 1.2 M⊙ yr -1 Mpc-3. The SFRs at all redshifts are within 3 σ of the average over all redshifts. © 2006. The American Astronomical Society. All rights reserved.
• Thompson, R. I., Sauvage, M., Kennicutt Jr., R. C., Engelbracht, C. W., & Vanzi, L. (2006). Delayed photoionization feedback in a super star cluster in SBS 0335-052E. Astrophysical Journal Letters, 638(1 I), 176-182.
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  Abstract: SBS 0335-052 is a well-studied blue compact dwarf galaxy with one of the lowest metallicities of any known galaxy. It also contains six previously identified super star clusters. We combine archival HST NICMOS images in the Paα line and the 1.6 μm continuum of the eastern component, SBS 0335-052E, with other space- and ground-based data to perform a multiwavelength analysis of the super star clusters. We concentrate on the southernmost clusters, designated S1 and S2, which appear to be the youngest clusters and are the strongest emitters of Paα, radio, and X-ray flux. Our analysis leads to a possible model for S1 and perhaps S2 as a cluster of very young, massive stars with strong stellar winds. The wind density can be high enough to absorb the majority of ionizing photons within less than 1000 AU of the stars, creating very compact H II regions that emit optically thick radiation at radio wavelengths. These winds would then effectively quench the photoionizing flux very close to the stars. This can delay the onset of negative feedback by photoionization and photodissociation on star formation in the clusters. This is significant since SBS 0335-052E resembles the conditions that were probably common for high-redshift star formation in galaxies near the epoch of reionization. © 2006. The American Astronomical Society. All rights reserved.
• Zoran, O., Barkana, R., & Thompson, R. I. (2006). A cosmic relation between extinction and star formation. Monthly Notices of the Royal Astronomical Society: Letters, 368(1), L47-L51.
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  Abstract: We study the relation between the star formation intensity of galaxies and the extinction by dust of their emitted light. We employ a detailed statistical analysis of Hubble Deep Field North data to show a clear positive correlation between the extinction and star formation intensity at all epochs from redshift 0.4 to 6.5. The extinction evidently increases with time for a given star formation intensity, consistent with the expected increase in the metallicity with time. Our observational results are well fitted at all epochs by a double-power-law model with a fixed shape that simply shifts with redshift. The correlation between the extinction and the star formation intensity can be interpreted by combining two other trends: the correlation between the star formation rate and the gas content of galaxies, and the evolution of the dust-to-gas ratio in galaxies. If we assume that Kennicutt's observed relation for the former is valid at each redshift, then our findings imply an interesting variation in the dust-to-gas ratio in galaxies within each epoch and with time, and suggest new ways to investigate the cosmic evolution of this quantity. © 2006 The Authors. Journal compilation © 2006 RAS.
• Bouwens, R. J., Illingworth, G. D., Thompson, R. I., & Franx, M. (2005). Constraints on z ≈ 10 galaxies from the deepest Hubble Space Telescope NICMOS fields. Astrophysical Journal Letters, 624(1 II), L5-L8.
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  Abstract: We use all available fields with deep NICMOS imaging to search for J 110-dropouts (H160,AB ≲ 28) at z ≈ 10. Our primary data set for this search is the two J110 + H160 ICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5 σ limiting magnitudes were ∼28.6 in J 110 and ∼28.5 in H160 (0″.6 apertures). Several shallower fields were also used: J110 + H160 NICMOS frames available over the Hubble Deep Field (HDF) North, the HDF-South NICMOS parallel, and the ACS UDF (with 5 a limiting magnitudes in J110 and H160 ranging from 27.0 to 28.2). The primary selection criterion was (J110-H160)AB > 1-8. Eleven such sources were found in all search fields using this criterion. Eight of these are clearly ruled out as credible z ≈ 10 sources, either as a result of detections (>2 a) blueward of J110 or their colors redward of the break (H160-K ∼ 1.5) (redder than ≳98% of lower redshift dropouts). The nature of the three remaining sources could not be determined from the data. This number appears consistent with the expected contamination from low-redshift interlopers. Analysis of the stacked images for the three candidates also suggests some contamination. Regardless of their true redshifts, the actual number of z ≈ 10 sources must be three or fewer. To assess the significance of these results, two lower redshift samples (a z ∼ 3.8 B-dropout and z ∼ 6 i-dropout sample) were projected to z ∼ 7-13 using a (1 + z) -1 size scaling (for fixed luminosity). They were added to the image frames and the selection was repeated, giving 15.6 and 4.8 J110- dropouts, respectively. This suggests that to the limit of this probe (≈0.3Lz=3*), there has been evolution from z ∼ 3.8 and possibly from z ∼ 6. This is consistent with the strong evolution already noted at z ∼ 6 and z ∼ 7.5 relative to z ∼ 3-4. Even assuming that three sources from this probe are at z ≈ 10, the rest-frame continuum UV (∼1500 ̊) luminosity density at z ∼ 10 (integrated down to 0.3Lz=3*) is just 0.19-0.09+0.13 times that at z ∼ 3.8 (or 0.19-0.10+0.15 times, including the small effect from cosmic variance). However, if none of our sources are at z ≈ 10, this ratio has a 1 σ upper limit of 0.07. © 2005. The American Astronomical Society. All rights reserved.
• Meakin, C. A., Hines, D. C., & Thompson, R. I. (2005). Young stars and dust in AFGL 437: Hubble space telescope nicmos polarimetric imaging of an outflow source. Astrophysical Journal Letters, 634(2 I), 1146-1154.
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  Abstract: We present near-infrared broadband and polarimetric images of the compact star-forming cluster AFGL 437 obtained with the NICMOS instrument on board HST. Our high-resolution images reveal a well-collimated bipolar reflection nebulosity in the cluster and allow us to identify WK 34 as the illuminating source. The scattered light in the bipolar nebulosity centered on this source is very highly polarized (up to 79%). Such high levels of polarization imply a distribution of dust grains lacking large grains, contrary to the usual dust models of dark clouds. We discuss the geometry of the dust distribution giving rise to the bipolar reflection nebulosity and make mass estimates for the underlying scattering material. We find that the most likely inclination of the bipolar nebulosity, the south lobe inclined toward Earth, is consistent with the inclination of the large-scale CO molecular outflow associated with the cluster, strengthening the identification of WK 34 as the source powering it. © 2005. The American Astronomical Society. All rights reserved.
• Thompson, R. I., Illingworth, G., Bouwens, R., Dickinson, M., Eisenstein, D., Fan, X., Franx, M., Riess, A., Rieke, M. J., Schneider, G., Stobie, E., Toft, S., & Dokkum, P. V. (2005). The Near-Infrared Camera and Multi-Object Spectrometer Ultra Deep Field: Observations, data reduction, and galaxy photometry. Astronomical Journal, 130(1), 1-12.
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  Abstract: This paper describes the observations and data reduction techniques for the version 2.0 images and catalog of the Near-Infrared Camera and Multi-Object Spectrometer Ultra Deep Field (NICMOS UDF) Treasury program. All sources discussed in this paper are based on detections in the combined NICMOS F110W and F160W bands only. The NICMOS images are drizzled to 0.″09 pixel -1 and aligned to the Advanced Camera for Surveys UDF F850LP image, which was rebinned to the same pixel scale. These form the NICMOS version 2.0 UDF images. The catalog sources are chosen with a conservative detection limit to avoid the inclusion of numerous spurious sources. The catalog contains 1293 objects in the 144″ × 144″ NICMOS subfield of the UDF. The 5 σ signal-to-noise ratio level is an average 0.″6 diameter aperture AB magnitude of 27.7 at 1.1 and 1.6 μm. The catalog sources, listed in order of right ascension, satisfy a minimum signal-to-noise ratio criterion of 1.4 σ in at least seven contiguous pixels of the combined F110W and F160W image. © 2005. The American Astronomical Society. All rights reserved.
• Toft, S., Dokkum, P. V., Franx, M., Thompson, R. I., Illingworth, G. D., Bouwens, R. J., & Kriek, M. (2005). Distant red galaxies in the hubble ultra deep field. Astrophysical Journal Letters, 624(1 II), L9-L12.
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  Abstract: We take advantage of the Hubble Ultra Deep Field data to study the rest-frame optical and UV morphologies of the novel population of distant red galaxies (DRGs). Six galaxies with J-Ks> 2.3 are found to K s = 21.5, five of which have photometric redshifts zphot ≳ 2, corresponding to a surface density of 0.9 arcmin-2. The surface brightness distributions of the zphot ≳ 2 galaxies are better represented by exponential disks than R1/4 laws. Two of the zphot ≳ 2 galaxies are extended, while three have compact morphologies. The rest-frame optical morphology of the zphot ≳ 2 galaxies is quite different from the rest-frame UV morphology: All the galaxies have red central components that dominate in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) H160-band images, as well as distinct off-center blue features that show up in (and often dominate) the Advanced Camera for Surveys (ACS) images. The mean measured effective radius of the zphot ≳ 2 galaxies is (re) = 1.9 ± 1.4 kpc, similar (within the errors) to the mean size of Lyman break galaxies at similar redshifts. All the DRGs are resolved in the ACS images, while four are resolved in the NICMOS images. Two of the zphot ≳ 2 galaxies are bright X-ray sources and hence host active galactic nuclei (AGNs). One of these galaxies is resolved in the ACS and NICMOS images, which means that the AGN does not dominate its rest-frame UV/optical spectral energy distribution (SED), while the other is unresolved in the NICMOS images and hence could have an AGN-dominated SED. The diverse rest-frame optical and UV morphological properties of DRGs derived here suggest that they have complex stellar populations consisting of both evolved populations, which dominate the mass and the rest-frame optical light, and younger populations that show up as patches of star formation in the rest-frame UV light, in many ways resembling the properties of normal local galaxies. This interpretation is supported by fits to the broadband SEDs, which for all five zphot ≳ 2 galaxies are best represented by models with extended star formation histories and substantial amounts of dust. © 2005. The American Astronomical Society. All rights reserved.
• Bouwens, R. J., Illingworth, G. D., Thompson, R. I., Blakeslee, J. P., Dickinson, M. E., Broadhurst, T. J., Eisenstein, D. J., Fan, X., Franx, M., Meurer, G., & Dokkum, P. V. (2004). Star formation at z ∼ 6: The hubble ultra deep parallel fields. Astrophysical Journal Letters, 606(1 II), L25-L28.
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  Abstract: We report on the i-dropouts detected in two exceptionally deep Advanced Camera for Surveys fields (B435, V606, i775, and z850 with 10 σ limits of 28.8, 29.0, 28.5, and 27.8, respectively) taken in parallel with the Ultra Deep Field Near-Infrared Camera and Multi-Object Spectrometer observations. Using an i-z > 1.4 cut, we find 30 i-dropouts over 21 arcmin2 down to z850, AB = 28.1, or 1.4 i-dropouts arcmin-2, with significant field-to-field variation (as expected from cosmic variance). This extends i-dropout searches some ∼0.9 mag further down the luminosity function than was possible in the Great Observatories Origins Deep Survey (GOODS) fields, yielding a ∼7 times increase in surface density. An estimate of the size evolution for UV-bright objects is obtained by comparing the composite radial flux profile of the bright i-dropouts (z850, AB < 27.2) with scaled versions of the Hubble Deep Field-North and -South U-dropouts. The best fit is found with a (1 + z)-1.57 +0.50 -0.53 scaling in size (for fixed luminosity), extending lower redshift (1 < z < 5) trends to z ∼ 6. Adopting this scaling and the brighter i-dropouts from both GOODS fields, we make incompleteness estimates and construct a z ∼ 6 luminosity function (LF) in the rest-frame continuum UV (∼1350 Å) over a 3.5 mag baseline, finding a shape consistent with that found at lower redshift. To evaluate the evolution in the LF from z ∼ 3.8, we make comparisons against different scalings of a lower redshift B-dropout sample. Although a strong degeneracy is found between luminosity and density evolution, our best-fit model scales as (1 + z) -2.8 in number and (1 + z)0.1 in luminosity, suggesting a rest-frame continuum UV luminosity density at z ∼ 6 that is just 0.38 -0.07+0.09 times that at z ∼ 3.8. Our inclusion of the size evolution makes the present estimate lower than previous z ∼ 6 estimates.
• Bouwens, R. J., Thompson, R. I., Illingworth, G. D., Franx, M., Dokkum, P. V., Fan, X., Dlckinson, M. E., Eisenstein, D. J., & Rieke, M. J. (2004). Galaxies at z ∼ 7-8: Z₈₅₀-dropouts in the hubble ultra deep field. Astrophysical Journal Letters, 616(2 II), L79-L82.
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  Abstract: We have detected likely z ∼ 7-8 galaxies in the 144″ × 144″ Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) observations of the Hubble Ultra Deep Field. Objects are required to be ≥3 σ detections in both NICMOS bands, J110 and H160. The selection criteria for this sample are (z850 - J 110)AB > 0.8, (z850 - J110) AB > 0.66(J110 - H160)AB + 0.8, (J110 - H160)AB < 1.2 and no detection at less than 8500 Å. The five selected sources have total magnitudes H 160, AB ∼ 27. Four of the five sources are quite blue compared to typical lower redshift dropout galaxies and are clustered within a 1 arcmin2 region. Because all five sources are near the limit of the NICMOS data, we have carefully evaluated their reality. Each of the candidates is visible in different splits of the data and a median stack. We analyzed several noise images and estimate the number of spurious sources to be 1 ± 1. A search using an independent reduction of this same data set clearly revealed three of the five candidates and weakly detected a fourth candidate, suggesting that the contamination could be higher. For comparison with predictions from lower redshift samples, we take a conservative approach and adopt four z ∼ 7-8 galaxies as our sample. With the same detection criteria on simulated data sets, assuming no evolution from z ∼ 3.8, we predict 10 sources at z ∼ 7-8, or 14 if we use a more realistic (1 + z) -1 size scaling. We estimate that the rest-frame continuum UV (∼1800 Å) luminosity density at z ∼ 7.5 (integrated down to 0.3L*z=3) is just 0.20-0.08+0.12 times that found at z ∼ 3.8 (or 0.20-0.12+0.23 times this quantity including cosmic variance). Effectively this sets an upper limit on the luminosity density down to 0.3L*z=3 and is consistent with significant evolution at the bright end of the luminosity function from z ∼ 7.5 to 3.8. Even with the lower UV luminosity density at z ∼ 7.5, it appears that galaxies could still play an important role in reionization at these redshifts, although definitive measurements remain to be made.
• Jensen, J. B., Tonry, J. L., Barris, B. J., Thompson, R. I., Liu, M. C., Rieke, M. J., Ajhar, E. A., & Blakeslee, J. P. (2003). Measuring distances and probing the unresolved stellar populations of galaxies using infrared surface brightness fluctuations. Astrophysical Journal Letters, 583(2 I), 712-726.
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  Abstract: To empirically calibrate the IR surface brightness fluctuation (SBF) distance scale and probe the properties of unresolved stellar populations, we measured fluctuations in 65 galaxies using NICMOS on the Hubble Space Telescope. The early-type galaxies in this sample include elliptical and S0 galaxies and spiral bulges in a variety of environments. Absolute fluctuation magnitudes in the F160W (1.6 μm) filter (M̄F160W) were derived for each galaxy using previously measured I-band SBF and Cepheid variable star distances. F160W SBFs can be used to measure distances to early-type galaxies with a relative accuracy of ∼10%, provided that the galaxy color is known to ∼0.035 mag or better. Near-IR fluctuations can also reveal the properties of the most luminous stellar populations in galaxies. Comparison of F160W fluctuation magnitudes and optical colors to stellar population model predictions suggests that bluer elliptical and S0 galaxies have significantly younger populations than redder ones and may also be more metal-rich. There are no galaxies in this sample with fluctuation magnitudes consistent with old, metal-poor (t > 5 Gyr, [Fe/H] > -0.7) stellar population models. Composite stellar population models imply that bright fluctuations in the bluer galaxies may be the result of an episode of recent star formation in a fraction of the total mass of a galaxy. Age estimates from the F160W fluctuation magnitudes are consistent with those measured using the Hβ Balmer-line index. The two types of measurements make use of completely different techniques and are sensitive to stars in different evolutionary phases. Both techniques reveal the presence of intermediate-age stars in the early-type galaxies of this sample.
• Storrie-Lombardi, L. J., Weymann, R. J., & Thompson, R. I. (2003). High-redshift candidates and the nature of small galaxies in the hubble deep field. Astrophysical Journal Letters, 591(2 I), 623-639.
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  Abstract: We present results on two related topics: (1) a discussion of high-redshift candidates (z > 4.5) and (2) a study of very small galaxies at intermediate redshifts, both sets being detected in the region of the northern Hubble Deep Field (HDF) covered by the deep NICMOS observations at 1.6 and 1.1 μm. The high-redshift candidates are just those with redshift z > 4.5 as given in the recent catalog of Thompson, Weymann, and Storrie-Lombardi, while the " small galaxy " sample is defined to be those objects with isophotal area ≤0.2 arcsec2 and with photometric redshift 1 ≤ z ≤ 4.5. Of the 19 possible high-redshift candidates listed in the Thompson et al. catalog, 11 have (nominal) photometric redshifts less than 5.0. Of these, however, only four are "robust" in the sense of yielding high redshifts when the fluxes are randomly perturbed with errors comparable to the estimated measuring error in each wave band. For the eight other objects with nominal photometric redshifts greater than 5.0, one (WFPC2 4-473) has a published spectroscopic redshift. Of the remaining seven, four are robust in the sense indicated above. Two of these form a close pair (NIC 586 and NIC 107). The redshift of the object having formally the highest redshift, at 6.56 (NIC 118 = WFPC2 4-601), is problematic, since F606W and F814W flux are clearly present, and the nature of this object poses a dilemma. Previous work by Colley et al. has suggested that compact sources in the WFPC2 HDF images are subgalactic components at redshifts z > 0.5 since they are correlated on scales less than 1″, corresponding to physical scales of less than 8 kpc (Ho = 65 km s-1 Mpc-1, qo = 0.125). We confirm these correlations in the WFPC2 data. However, we do not detect the correlation of close pairs of galaxies on small scales in the ∼0.65 arcmin2 region of the HDF that we surveyed with NICMOS. The smaller area surveyed and lower resolution will make any real correlation more difficult to measure in these data. We have examined averaged images of these faint ( V606 ∼ 27-29), compact objects to search for extended, surrounding flux from older, fainter populations of stars. We find no evidence from the averaged images that isolated, compact objects in the Hubble Deep Field are embedded in fainter, more extended galaxies. For three different assumptions about possible star formation histories in these objects we set limits on the total amount of stars that could have been formed in an annulus corresponding to radii between ∼ 6 and 10 kpc, which is typically a few times 108 M⊙. We suggest that some of these objects may be protogalactic fragments.
• Thompson, R. I. (2003). Six constraints (or inputs) from the northern HDF for theoretical galaxy formation models. Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias, 17, 237-238.
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  Abstract: Six constraints on models of galaxy formation are presented. Two constraints pertain to the choice between hierarchical formation and passive evolution. Three constraints pertain to the luminosity function and its evolution and a final constraint addresses the specific star formation intensity distribution function. All of the constraints result from observations in the NHDF.
• Thompson, R. I. (2003). Star formation history and other properties of the northern Hubble Deep Field. Astrophysical Journal Letters, 596(2 I), 748-767.
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  Abstract: The original analysis of the star formation history in the NICMOS deep images of the northern Hubble Deep Field (NHDF) is extended to the entire NHDF utilizing NICMOS and WFPC2 archival data. The roughly constant star formation rate from redshifts 1-6 found in this study is consistent with the original results. Star formation rates from this study, Lyman break galaxies, and submillimeter observations are now in concordance. The spike of star formation at redshift 2 due to two ultraluminous IR galaxies in the small deep NICMOS field is smoothed out in the larger area results presented here. The larger source base of this study allows comparison with predictions from hierarchical galaxy formation models. In general, the observation are consistent with the predictions. The observed luminosity functions at redshifts 1-6 are presented for future comparisons with theoretical galaxy evolution calculations. Mid- and far-infrared properties of the sources are also calculated and compared with observations. A candidate for the VLA source VLA 3651 + 1221 is discussed.
• Thompson, R. I. (2003). Tests and constraints on theories of galaxy formation and evolution. Astrophysics and Space Science, 284(2), 353-356.
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  Abstract: Tests and constraints on current theories of galaxy formation and evolution are presented. They are derived from observations of the Northern Hubble Deep Field with WFPC2 and NICMOS. Photometric redshifts, extinctions and spectral energy distributions are calculated for all objects in the field. The tests and constraints are derived from the output of this analysis. The tests of the predictions from hierarchical and pure luminosity evolution galaxy evolution calculations favor the hierarchical model. Constraints are provided by the current luminosity function and its evolution to a redshift of 6.
• Bunker, A. J., Spinrad, H., McLure, R., Dey, A., Dunlop, J., Peacock, J., Stern, D., Thompson, R., Waddington, I., & Windhorst, R. (2002). HST imaging of an old galaxy group at Z = 1.55. Astrophysics and Space Science, 281(1-2), 527-528.
• Thompson, R. I. (2002). Galaxy evolution in the Northern HDF. Astrophysics and Space Science, 281(1-2), 445-448.
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  Abstract: The history of star formation in the Northern Hubble Deep Field is probed using a combination of optical and near infrared images taken with WFPC2 and NICMOS on the Hubble Space Telescope. These images cover more than a factor of five in wavelength. This broad wavelength coverage allows accurate photometric determinations of redshift, extinction and intrinsic spectral energy distribution for each galaxy. From these parameters the star formation rate for each galaxy is determined by relating the 1500 angstrom flux to the net star formation rate. We then correct the rates at high redshift for the effects of surface brightness dimming by using a standard form of the star formation intensity distribution. Our measurements show that the star formation rate in the Northern HDF is roughly constant from a redshift of 1 through 6.
• Thompson, R. I. (2002). Matching the observed star formation intensity distribution with empirical laws. Astrophysical Journal Letters, 581(2 II), L85-L88.
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  Abstract: This Letter matches the shape of the star formation intensity distribution function to empirical laws such as the Schmidt law. The shape of the distribution at a redshift of 1 is reproduced from the empirical Schmidt law with a critical density, a Schechter distribution of galaxy masses, and the assumption that star formation occurs mainly in exponential disks. The shape of the distribution depends primarily on two values: the characteristic mass m* in the Schechter mass distribution and the characteristic radius r e in the exponential disk. As these characteristic values evolve, they will affect the shape of the distribution function. The expected direction of evolution of the parameters partially cancel each other, leaving the distribution shape relatively invariant.
• Thompson, R. I. (2002). The NICMOS observational program: Some personal examples. Advances in Space Research, 30(9), 2071-2080.
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  Abstract: This paper reviews a few of the author's observational programs with the Near Infrared Camera and Multi-Object Spectrometer on the Hubble Space Telescope. These programs are taken as being partially representative of the very large body of observations carried out by NICMOS in both General Observer and Guaranteed Time Observer scientific programs. © 2002 Published by Elsevier Science Ltd on behalf of COSPAR.
• Thompson, R. I., Smith, B. A., & Hester, J. J. (2002). Embedded star formation in the Eagle Nebula. Astrophysical Journal Letters, 570(2 I), 749-757.
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  Abstract: M16 (=NGC 6611), the Eagle Nebula, is a well-studied region of star formation and the source of a widely recognized Hubble Space Telescope (HST) image. High spatial resolution infrared observations with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) on HST reveal the detailed morphology of two embedded star formation regions that are heavily obscured at optical wavelengths. It is striking that only limited portions of the visually obscured areas are opaque at 2.2 μm. Although the optical images imply substantial columns of material, the infrared images show only isolated clumps of dense gas and dust. Rather than being an active factory of star production, only a few regions are capable of sustaining current star formation. Most of the volume in the columns may be molecular gas and dust, protected by capstones of dense dust. Two active regions of star formation are located at the tips of the optical northern and central large "elephant trunk" features shown in the Wide Field Planetary Camera 2 (WFPC2) images. They are embedded in two capstones of infrared opaque material that contains and trails behind the sources. Although the presence of these sources was evident in previous observations at the same and longer wavelengths, the NICMOS images provide a high-resolution picture of their morphology. Two bright stars appear at the tip of the southern column and may be the result of recent star formation at the top of that column. These observations suggest that the epoch of star formation in M16 may be near its endpoint.
• Corbin, M. R., Urban, A., Stobie, E., Thompson, R. I., & Schneider, G. (2001). A multivariate analysis of galaxies in the Hubble Deep Field-North. Astrophysical Journal Letters, 551(1 PART 1), 23-36.
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  Abstract: We use the ultraviolet and optical WFPC2 and near-infrared NICMOS images of the Hubble Deep Field-North to measure and statistically compare an array of parameters for over 250 of the galaxies it contains. These parameters include redshift, rest-frame visible asymmetry and concentration, bolometric luminosity, and extinction-corrected star formation rale. We find only one strong correlation, between bolometric luminosity and star formation rate, from which early-type galaxies noticeably deviate. When our asymmetry measurements are combined with those of a sample of nearby galaxies covering the full Hubble sequence, we find a weak correlation between redshift and rest-frame visible asymmetry, consistent with the qualitative evidence of galaxy morphological evolution from these and other deep Hubble Space Telescope images. The mean values of these asymmetry measurements show a monotonic increase with redshift interval over the range 0 ≲ z ≲ 2, increasing by a factor of approximately 3. If this trend is real, it suggests that galaxy morphological evolution within the last ∼ 70% of the Hubble time is a gradual process that is continuing through the present cosmological epoch. There is evidence that the dominant source of this evolution is the "minor" mergers of disk galaxies with smaller companions, which could also transform late-type spiral galaxies to early-type spiral galaxies. Interestingly, in contrast to local galaxies we find no correlations between galaxy star formation rate and either UV or visible asymmetry. This could arise if the star formation of high-redshift galaxies proceeds in episodes that are short (∼ 100 Myr) relative to the timescales over which galaxy mergers produce strong asymmetries (∼ 500 Myr), a result suggested by the high star formation rates of Lyman break galaxies. Subject headings: cosmology: observations - galaxies: evolution -galaxies: fundamental parameters -galaxies: structure.
• Cotera, A. S., Whitney, B. A., Young, E., Wolff, M. J., Wood, K., Povich, M., Schneider, G., Rieke, M., & Thompson, R. (2001). High-resolution near-infrared images and models of the circumstellar disk in HH 30. Astrophysical Journal Letters, 556(2 PART 1), 958-969.
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  Abstract: We present Hubble Space Telescope near-infrared camera and multiobject spectrometer observations of the reflection nebulosity associated with the T Tauri star HH 30. The images show the scattered-light pattern characteristic of a highly inclined, optically thick disk with a prominent dust lane whose width decreases with increasing wavelength. The reflected nebulosity exhibits a lateral asymmetry in the upper lobe on the opposite side to that reported in previously published Wide Field Planetary Camera 2 images. The radiation transfer model that most closely reproduces the data has a flared accretion disk with dust grains larger than standard interstellar medium grains by a factor of approximately 2.1. A single hot spot on the stellar surface provides the necessary asymmetry to fit the images and is consistent with previous modeling of the light curve and images. Photometric analysis results in an estimated extinction of Av ≳ 80; however, since the photometry measures only scattered light rather than direct stellar flux, this a lower limit. The radiative transfer models require an extinction of Av = 7900.
• Jensen, J. B., Tonry, J. L., Thompson, R. I., Ajhar, E. A., Lauer, T. R., Rieke, M. J., Postman, M., & Liu, M. C. (2001). The infrared surface brightness fluctuation hubble constant. Astrophysical Journal Letters, 550(2 PART 1), 503-521.
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  Abstract: We measured infrared surface brightness fluctuation (SBF) distances to an isotropically distributed sample of 16 distant galaxies with redshifts reaching 10,000 km s-1 using the near-IR camera and multi-object spectrometer (NICMOS) on the Hubble Space Telescope (HST). The excellent spatial resolution, very low background, and brightness of the IR fluctuations yielded the most distant SBF measurements to date. Twelve nearby galaxies were also observed and used to calibrate the F160W (1.6 μm) SBF distance scale. Of these, three have Cepheid variable star distances measured with HST and eleven have optical I-band SBF distance measurements. A distance modulus of 18.5 mag to the Large Magellanic Cloud was adopted for this calibration. We present the F160W SBF Hubble diagram and find a Hubble constant H0 = 76 ± 1.3 (1 σ statistical) ±6 (systematic) km s-1 Mpc-1. This result is insensitive to the velocity model used to correct for local bulk motions. Restricting the fit to the six most distant galaxies yields the smallest value of H0 = 72 ± 2.3 km s-1 Mpc-1 that is consistent with the data. This 6% decrease in the Hubble constant is consistent with the hypothesis that the Local Group inhabits an underdense region of the universe, but is also consistent with the best-fit value of H0 = 76 km s-1 Mpc-1 at the 1.5 σ level.
• Riess, A. G., Nugent, P. E., Gilliland, R. L., Schmidt, B. P., Tonry, J., Dickinson, M., Thompson, R. I., Budavári, T., Casertano, S., Evans, A. S., Filippenko, A. V., Livio, M., Sanders, D. B., Shapley, A. E., Spinrad, H., Steidel, C. C., Stern, D., Surace, J., & Veilleux, S. (2001). The farthest known supernova: Support for an accelerating universe and a glimpse of the epoch of deceleration. Astrophysical Journal Letters, 560(1 PART 1), 49-71.
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  Abstract: We present photometric observations of an apparent Type Ia supernova (SN Ia) at a redshift of ∼1.7, the farthest SN observed to date. The supernova, SN 1997ff, was discovered in a repeat observation by the Hubble Space Telescope (HST) of the Hubble Deep Field-North (HDF-N) and serendipitously monitored with NICMOS on HST throughout the Thompson et al. Guaranteed-Time Observer (GTO) campaign. The SN type can be determined from the host galaxy type: an evolved, red elliptical lacking enough recent star formation to provide a significant population of core-collapse supernovae. The classification is further supported by diagnostics available from the observed colors and temporal behavior of the SN, both of which match a typical SN Ia. The photometric record of the SN includes a dozen flux measurements in the I, J, and H bands spanning 35 days in the observed frame. The redshift derived from the SN photometry, z = 1.7 ± 0.1, is in excellent agreement with the redshift estimate of z = 1.65 ± 0.15 derived from the U300 B450 V606 I814 J110 J125 H160 H165 Ks photometry of the galaxy. Optical and near-infrared spectra of the host provide a very tentative spectroscopic redshift of 1.755. Fits to observations of the SN provide constraints for the redshift-distance relation of SNe Ia and a powerful test of the current accelerating universe hypothesis. The apparent SN brightness is consistent with that expected in the decelerating phase of the preferred cosmological model, ΩM ≈ 1/3, ΩΛ ≈ 2/3. It is inconsistent with gray dust or simple luminosity evolution, candidate astrophysical effects that could mimic previous evidence for an accelerating universe from SNe Ia at z ≈ 0.5. We consider several sources of potential systematic error, including gravitational lensing, supernova misclassification, sample selection bias, and luminosity calibration errors. Currently, none of these effects alone appears likely to challenge our conclusions. Additional SNe Ia at z > 1 will be required to test more exotic alternatives to the accelerating universe hypothesis and to probe the nature of dark energy.
• Scoville, N. Z., Polletta, M., Ewald, S., Stolovy, S. R., Thompson, R., & Rieke, M. (2001). High-mass, OB star formation in M51: Hubble space telescope Hα and Paα imaging. Astronomical Journal, 122(6), 3017-3045.
• Thompson, R. I., Chary, R., Corbin, M. R., & Epps, H. (2001). The location of the nucleus and the morphology of emission-line regions in NGC 1068. Astrophysical Journal Letters, 558(2 PART 2), L97-L100.
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  Abstract: This Letter presents new Near-Infrared Camera and Multi-Object Spectrometer data on the location of the nucleus and the morphology of hydrogen and [Si VI] emission in NGC 1068. The peak of the emission at 2.2 μm is a strong point source that marks the location of the nucleus. The [Si VI] line emission region consists of two main components, a diffuse region of coronal emission to the north-northeast of the nucleus and a bright emission spot 1″.6 from the nucleus along the direction of the radio jet. A similar but less intense emission spot also occurs in the hydrogen Paschen-α and Wide Field Planetary Camera 2 Hα images. The accurate determination of the nuclear position and its relation to the emission-line morphology produces a clearer picture of the nature of the interaction between the radio jet and its surroundings.
• Thompson, R. I., Weymann, R. J., & Storrie-Lombardi, L. J. (2001). Star formation history in the nicmos northern Hubble Deep Field. Astrophysical Journal Letters, 546(2 PART 1), 694-718.
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  Abstract: We present the results of an extensive analysis of the star formation rates determined from the NICMOS deep images of the northern Hubble Deep Field. We use SED template fitting photometric techniques to determine both the redshift and the extinction for each galaxy in our field. Measurement of the individual extinctions provides a correction for star formation hidden by dust obscuration. We determine star formation rates for each galaxy based on the 1500 Å UV flux and add the rates in redshift bins of width 1.0 centered on integer redshift values. We find a rise in the star formation rate from a redshift of 1 to 2 then a falloff from a redshift of 2 to 3. However, within the formal limits of the error bars this could also be interpreted as a constant star formation rate from a redshift of 1 to 3. The star formation rate from a redshift of 3 to 5 is roughly constant followed by a possible drop in the rate at a redshift of 6. The measured star formation rate at a redshift of 6 is approximately equal to the present day star formation rate determined in other work. The high star formation rate measured at a redshift of 2 is due to the presence of two possible ULIRGs in the field. If real, this represents a much higher density of ULIRGs than measured locally. We also develop a new method to correct for faint galaxies or faint parts of galaxies missed by our sensitivity limit, based on the assumption that the star formation intensity distribution function is independent of redshift. We measure the 1.6 μm surface brightness due to discrete sources and predict the 850 μm brightness of all of our galaxies based on the determined extinction. We find that the far-infrared fluxes predicted in this manner are consistent with the lack of detections of 850 μim sources in the deep NICMOS HDF, the measured 850 μm sky brightness due to discrete sources and the ratio of optical-UV sky brightness to far-infrared sky brightness. From this we infer that we are observing a population of sources that contributes significantly to the total star formation rate and these sources are not overwhelmed by the contribution from sources such as the extremely superluminous galaxies represented by the SCUBA detections. We have estimated the errors in the star formation rate due to a variety of sources including photometric errors, the near-degeneracy between reddening and intrinsic spectral energy distribution as well as the effects of sampling errors and large-scale structure. We have tried throughout to give as realistic and conservative an estimate of the errors in our analysis as possible.
• Corbin, M. R., O'Neil, E., Thompson, R. I., Rieke, M. J., & Schneider, G. (2000). A color analysis of the NICMOS parallel image archive. Astronomical Journal, 120(3), 1209-1220.
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  Abstract: We present a photometric analysis of all high Galactic latitude (|b\ > 20°) broadband parallel images taken by the Near-Infrared Camera and Multi-Object Spectrometer instrument of the Hubble Space Telescope during its initial lifetime in HST Cycle 7. These images, taken through the F110W and F160W filters, reach a mean 3 σ limiting magnitude of approximately 22 in both bands, and cover a total area of approximately 92 arcmin2. The reddest of the 358 galaxies detected have F110W-F160W colors and F160W magnitudes consistent with being a combination of both dusty star-forming and evolved early-type galaxies at 1 ≲ z ≲ 2. The surface density of these galaxies is comparable to that of the population of extremely red objects (EROs) discovered in ground-based surveys ( ∼ 100 deg-2), suggesting that EROs also represent a combination of both galaxy types in this redshift range. Roughly 10% of the detected galaxies appear to be blue compact dwarf galaxies at z ≲ 1, a result consistent with studies of the HST Medium Deep Survey fields. The surface density of these objects down to a magnitude of 22 in F160W is ∼ 300 deg-2. None of the 631 point sources detected have F110W -F160W colors matching those expected for quasi-stellar objects (QSOs) whose continua have been significantly reddened by internal dust. Our data limit the surface density of such QSOs to be ≲, 50 deg-2 down to the mean limiting magnitudes of the sample images. Since the surface density of QSOs detected on the basis of ultraviolet excess in optical surveys to comparable depth is ∼ 100 deg-2, this argues against the suggestion that dust-reddened QSOs compose the undetected majority of the QSO population. The F110W-F160W color can also be used to identify unreddened QSOs at z ≳ 8, but we find no such candidates. This is consistent with the evidence that QSO space density declines sharply at z ≳ 5.
• Corbin, M. R., Vacca, W. D., O'Neil, E., Thompson, R. I., Rieke, M. J., & Schneider, G. (2000). Photometric redshifts and morphologies of galaxies in the NICMOS parallel fields. Astronomical Journal, 119(3), 1062-1077.
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  Abstract: We present positions, magnitudes, sizes, and morphological classifications for 111 galaxies discovered in the Hubble Space Telescope NICMOS camera 1 and camera 2 parallel fields. We combine the magnitudes measured in the JHK-analog filters with those from deep ground-based images in V and/or R to measure photometric redshifts for 71 objects using Bruzual & Charlot population synthesis models. We find that these objects fall in the range z ∼ 0.0-2.7, with 〈Z〉 ≅ 0.8 and a mean luminosity 〈L〉 ≅ 1.6L*. The NICMOS images reveal many of the galaxies to be ordered spirals and ellipticals similar to those in the local universe, with a high degree of symmetry and brightness profiles that are well fitted by de Vaucouleurs's r1/4 and exponential disk laws. However, we find a higher fraction (∼14%) of morphologically peculiar and/or interacting galaxies in the sample than is observed among local galaxies (∼3%-4%). This is consistent with the result from other deep HST images including the Hubble Deep Field and Hubble Medium Deep Survey field that the fraction of peculiar and interacting galaxies increases with redshift. As the NICMOS images of the sample galaxies cover their rest-frame near-infrared and optical emission, this result increases confidence that such changes in morphology are genuine, as opposed to an effect produced by viewing galaxies in the rest-frame ultraviolet. We also find that at least 26 of the sample galaxies appear to be members of (noninteracting) pairs or groups, based on their promixity to one another and photometric redshifts. This is consistent with the results of recent ground-based optical surveys for faint galaxies covering larger areas and with the detection of galaxy groups and filaments at redshifts higher than those covered by the present sample.
• Scoville, N. Z., Evans, A. S., Thompson, R., Rieke, M., Hines, D. C., Low, F. J., Dinshaw, N., Surace, J. A., & Armus, L. (2000). NICMOS imaging of infrared-luminous galaxies. Astronomical Journal, 119(3), 991-1061.
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  Abstract: We present near-infrared images obtained with the Hubble Space Telescope NICMOS camera for a sample of nine luminous [LIGs: LIR(8-1000 μm) ≥ 1011 L⊙] and 15 ultraluminous (ULIGS: LIR ≥ 1012 L⊙) infrared galaxies. The sample includes representative systems classified as warm (f25μm/f60μm > 0.2) and cold (f25μm/f60μm ≤ 0.2) based on the mid-infrared colors and systems with nuclear emission lines classified as H II (i.e., starburst), QSO, Seyfert, and LINER. The morphologies of the sample galaxies are diverse and provide further support for the idea that they are created by the collision or interactions of spiral galaxies. Although no new nuclei are seen in the NICMOS images, the NICMOS images do reveal new spiral structures, bridges, and circumnuclear star clusters. The colors and the luminosities of the observed clusters are consistent with them being young (107-108 yr), formed as a result of galactic interactions, and having masses much greater than those of Galactic globular clusters. In NGC 6090 and VV 114, they are preferentially situated along the area of overlap of the two galactic disks. With the exception of IR 17208-0018, all of the ULIGs have at least one compact (2.2 μm FWHM ≤ 200 pc) nucleus. Analysis of the near-infrared colors (i.e., m1.1-1.6 vs. m1.6-2.2) derived from 1″.1 diameter apertures suggests that the warm galaxies have near-infrared colors consistent with QSO + hot dust emission and the cold galaxies, as a group, have near-infrared colors consistent with reddened starlight. In addition, the cold ULIG UGC 5101 (and possibly three others) have near-infrared colors suggesting additional active galactic nucleus-like near-infrared components in their nuclei. In a 2 kpc diameter aperture measurement, the global colors of all of the cold galaxies except UGC 5101 are consistent with starlight with a few magnitudes of visual extinction. The general dichotomy of the near-infrared properties of the warm and the cold galaxies are further supported by the light distributions: seven of the eight warm galaxies have unresolved nuclear emission that contributes significantly (i.e., ≥30%-40%) to the total near-infrared luminosity. The smooth, more extended light observed in all of the galaxies is most likely composed of giant and supergiant stars, but evidence at longer wavelengths suggests that these stars contribute little to the high 8-1000 μm luminosity of these galaxies. Finally, light profiles of nine of the 24 systems were fitted well by an r1/4 law (and not so well by an exponential disk profile). Whether these star systems eventually become massive central bulges or giant elliptical galaxies will depend on how efficiently the present ISM is converted into stars.
• Hines, D. C., Low, F. J., Thompson, R. I., Weymann, R. J., & Storrie-Lombardi, L. J. (1999). The host galaxy of the broad absorption line QSO PG 1700 + 518 and its ring galaxy companion: Nicmos 1.6 micron imaging. Astrophysical Journal Letters, 512(1 PART 1), 140-144.
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  Abstract: The 1.6 μm Near Infrared Camera and Multiobject Spectrometer image of the broad absorption line QSO PG 1700 + 518 clearly resolves the QSO host galaxy and a ringlike companion. The companion is most likely a ring galaxy produced in a collision with the QSO galaxy ∼5 x 107 yr ago. The morphology of the PG 1700 + 518 system is very similar to IRAS 04505-2958 (Boyce et al. 1996). Both objects were identified in a sample of eight QSOs selected by "warm" far-IR colors and extreme IR luminosities (Low et al. 1988). All eight QSOs show signs of strong interaction, and the presence of two head-on colliding systems in this sample may suggest that small impact parameters favor the energizing of IR-luminous QSOs.
• Lowrance, P. J., McCarthy, C., Becklin, E. E., Zuckerman, B., Schneider, G., Webb, R. A., Hines, D. C., Kirkpatrick, J. D., Koerner, D. W., Low, F., Meier, R., Rieke, M., Smith, B. A., Terrile, R. J., & Thompson, R. I. (1999). A candidate substellar companion to CD -33°7795 (TWA 5). Astrophysical Journal Letters, 512(1 PART 2), L69-L72.
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  Abstract: We present the discovery of a candidate substellar object in a survey of young stars in the solar vicinity using the sensitivity and spatial resolution afforded by the NICMOS coronagraph on the Hubble Space Telescope. The H = 12.1 mag object was discovered approximately 2″ from the TW Hydrae association member CD -33°7795 (TWA 5), and the photometry implies a spectral type M8-M8.5, with a temperature of ∼2600 K. We estimate that the probability of a chance alignment with a background object of this nature is less than 2 × 10-5 and therefore postulate that the object (TWA 5B) is physically associated at a projected separation of 100 AU. Given the likely youth of the primary (∼10 Myr), current brown dwarf cooling models predict a mass of ≈20MJup for TWA 5B.
• McCarthy, P. J., Yan, L., Freudling, W., Teplitz, H. I., Malumuth, E. M., Weymann, R. J., Malkan, M. A., A., R., Gardner, J. P., Storrie-Lombardi, L. J., Thompson, R. I., Williams, R. E., & Heap, S. R. (1999). Emission-line galaxies from the NICMOS/Hubble Space Telescope grism parallel survey. Astrophysical Journal Letters, 520(2 PART 1), 548-563.
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  Abstract: We present the first results of a survey of random fields with the slitless G141 (λc = 1.5 μm, ΔλA = 0.8 μm) grism on the near-IR camera and multiobject spectrometer (NICMOS) on board the Hubble Space Telescope (HST). Approximately 64 arcmin2 have been observed at intermediate and high Galactic latitudes. The 3 σ limiting line and continuum fluxes in each field vary from 7.5 × 10-17 to 1 × 10-17 ergs cm-2 s-1, and from H = 20 to 22, respectively. Our median and area-weighted 3 σ limiting line fluxes within a 4 pixel aperture are nearly identical at 4.1 × 10-17 ergs cm-2 s-1 and are 60% deeper than the deepest narrowband imaging surveys from the ground. We have identified 33 emission-line objects and derive their observed wavelengths, fluxes, and equivalent widths. We argue that the most likely line identification is Hα and that the redshift range probed is from 0.75 to 1.9. The 2 σ rest-frame equivalent width limits range from 9 to 130 Å, with an average of 40 Å. The survey probes an effective comoving volume of 105 h-350 Mpc3 for q0 = 0.5. Our derived comoving number density of emission-line galaxies in the range 0.7 < z < 1.9 is 3.3 × 10-4 h350 Mpc-3, very similar to that of the bright Lyman break objects at z ∼ 3. The objects with detected emission lines have a median F160W magnitude of 20.4 (Vega scale) and a median Hα luminosity of 2.7 × 1042 ergs s-1. The implied star formation rates range from 1 to 324 M⊙ yr-1 with an average [N II] λλ16583, 6548 corrected rate of 21 M⊙ yr-1 for H0 = 50 km s-1 Mpc and q0 = 0.5 (34 M⊙ yr-1 for q0 = 0.1).
• Schneider, G., Smith, B. A., Becklin, E. E., Koerner, D. W., Meier, R., Hines, D. C., Lowrance, P. J., Terrile, R. J., Thompson, R. I., & Rieke, M. (1999). NICMOS imaging of the HR 4796A circumstellar disk. Astrophysical Journal Letters, 513(2 PART 2), L127-L130.
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  Abstract: We report the first near-infrared (NIR) imaging of a circumstellar annular disk around the young (∼8 Myr), Vega-like star HR 4796A. NICMOS coronagraph observations at 1.1 and 1.6 μm reveal a ringlike symmetrical structure that peaks in reflected intensity 1″.05 ± 0″.02 (∼70 AU) from the central A0 V star. The ring geometry, with an inclination of 73°.1 ± 1°.2 and a major axis position angle of 26°.8 ± 0°.6, is in good agreement with recent 12.5 and 20.8 μm observations of a truncated disk. The ring is resolved with a characteristic width of less than 0″.26 (17 AU) and appears abruptly truncated at both the inner and outer edges. The region of the disk-plane inward of ∼60 AU appears to be relatively free of scattering material. The integrated flux density of the part of the disk that is visible (greater than 0″.65 from the star) is found to be 7.6 ± 0.5 and 7.4 ± 1.2 mJy at 1.1 and 1.6 μm, respectively. Correcting for the unseen area of the ring yields total flux densities of 12.8 ± 1.0 and 12.5 ± 2.0 mJy, respectively (Vega magnitudes equal to 12.92 ± 0.08 and 12.35 ± 0.18). The NIR luminosity ratio is evaluated from these results and ground-based photometry of the star. At these wavelengths, Ldisk(λ)/L*(λ) is equal to 1.4 ± 0.2 × 10-3 and 2.4 ± 0.5 × 10-3, giving reasonable agreement between the stellar flux scattered in the NIR and that which is absorbed in the visible and reradiated in the thermal infrared. The somewhat red reflectance of the disk at these wavelengths implies a mean particle size in excess of several microns, which is larger than typical interstellar grains. The confinement of material to a relatively narrow annular zone implies dynamical constraints on the disk particles by one or more as yet unseen bodies.
• Thompson, R. I. (1999). Star formation in the NICMOS HDF. Astrophysics and Space Science, 269-270(1-4), 493-499.
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  Abstract: This contribution discusses the rate of star formation in the galaxies observed in the NICMOS Hubble Deep Field. A combination of the earlier fluxes from the WFPC II HDF measurements and the NICMOS near infrared measurement produces a superb data base for the application of photometric redshift techniques. By capitalizing on the extended wavelength coverage of this data we also determine the most likely extinction values for each galaxy. With these measurements we then calculate the star formation rate for each galaxy and determine the distribution of this rate with redshift. Our basic conclusion is that the star formation rate in the NICMOS HDF has been relatively constant for redshifts between 1 and 6.
• Thompson, R. I., & Corbin, M. (1999). NICMOS observations of two classic AGNs. Astrophysics and Space Science, 266(1-2), 79-83.
• Thompson, R. I., Storrie-Lombardi, L. J., Weymann, R. J., Rieke, M. J., Schneider, G., Stobie, E., & Lytle, D. (1999). Near-Infrared Camera and Multi-Object Spectrometer observations of the Hubble Deep Field: Observations, data reduction, and galaxy photometry. Astronomical Journal, 117(1), 17-39.
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  Abstract: This paper presents data obtained during the NICMOS Guaranteed Time Observations of a portion of the Hubble Deep Field. The data are in a catalog format similar to the publication of the original WFPC2 Hubble Deep Field program (Williams et al.). The catalog contains 342 objects in a 49″.1 x 48″.4 subfield of the total observed field, 235 of which are considered coincident with objects in the WFPC2 catalog. The 3 σ signal-to-noise ratio level is at an aperture AB magnitude of approximately 28.8 at 1.6 μm. The catalog sources, listed in order of right ascension, are selected to satisfy a limiting signal-to-noise ratio criterion of greater than or equal to 2.5. This introduces a few false detections into the catalog, and users should take careful note of the completeness and reliability levels for the catalog discussed in §§9 and 10. The catalog also contains a test parameter indicating the results of half-catalog tests and the degree of coincidence with the original WFPC2 catalog.
• Chen, H., Bally, J., O'Dell, C. R., Mccaughrean, M. J., Thompson, R. L., Rieke, M., Schneider, G., & Young, E. T. (1998). 2.12 Micron molecular hydrogen emission from circumstellar disks embedded in the orion nebula. Astrophysical Journal Letters, 492(2 PART II), L173-L176.
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  Abstract: We present narrowband images of two externally illuminated circumstellar disks embedded in the Orion Nebula. The images were taken with camera 2 of the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) as part of the Hubble Space Telescope Early Release Observations program. Molecular hydrogen emission is confined to the silhouettes embedded in the objects HST 10 (182-413) and HST 17 (183-419). This emission appears to trace the surfaces of nearly edge-on circumstellar disks and is likely to be excited by the intense far-ultraviolet (FUV) radiation field produced by nearby O stars. The presence of this emission confirms that FUV radiation penetrates to the disk surface. The absence of H2 emission in the region between the ionization front and the disk surface provides evidence that this medium is predominantly atomic. Our observations constitute the first demonstration that the dense circumstellar disks embedded in the proplyds are predominately molecular. While the central star is marginally detected at 2.15 μm in HST 10, the central star of HST 17 is clearly detected. © 1998. The American Astronomical Society. All rights reserved.
• Kulkarni, V. P., Calzetti, D., Bergeron, L., Rieke, M., Axon, D., Skinner, C., Colina, L., Sparks, W., Daou, D., Gilmore, D., Holfeltz, S., Mackenty, J., Noll, K., Ritchie, C., Schneider, G., Schultz, A., Storrs, A., Suchkov, A., & Thompson, R. (1998). Unveiling the hidden nucleus of IC 5063 with nicmos. Astrophysical Journal Letters, 492(2 PART II), L121-L124.
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  Abstract: We present high-resolution near-infrared images of the Seyfert 2 galaxy IC 5063 obtained using the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) in broadband filters at 1.1, 1.6, and 2.2 μm (FWHM ≈ 0′.21 at 2.2 μm). The images show a very red, unresolved point source at the center of the galaxy, confirming the existence of the obscured active nucleus inferred from previous ground-based studies. The 2.2 μm flux, supplemented with ground-based L′-band observations, suggests thermal emission equivalent to a blackbody at a temperature of 720 K. We ascribe the emission not to direct light from the nucleus, but to hot dust in the inner part of the torus. The 1.6 μm emission is only minimally affected by the hot dust emission. The luminosity of the central source producing most of the 1.6 μm emission, not corrected for extinction, is 1.5 × 1041 ergs s-1, integrated over the F160W filter only. We also present lower spatial resolution images of IC 5063 obtained with NICMOS in the emission lines of [Fe II] λ1.644 μm, Paα λ1.8756 μm, and H2 λ2.1218 μm. These images reveal a linear emission morphology comprised of two bright knots, separated by 1″.8 on either side of a central knot that is at the location of the continuum nucleus. A comparison with high-resolution radio continuum maps shows that there is a one-to-one spatial correspondence between the radio lobes and the emission-line knots, directly implying that the [Fe II] and H2 emission is created by fast shocks produced by the advancing radio jets. The asymmetry in the [Fe II]/H2 ratio may suggest a difference in either the shock velocities or the molecular mass on the two sides of the nucleus. © 1998. The American Astronomical Society. All rights reserved.
• McCaughrean, M. J., Chen, H., Bally, J., Erickson, E., Thompson, R., Rieke, M., Schneider, G., Stolovy, S., & Young, E. (1998). High-resolution near-infrared imaging of the Orion 114-426 silhouette disk. Astrophysical Journal Letters, 492(2 PART II), L157-L161.
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  Abstract: We present the first high-resolution near-infrared images of the edge-on silhouette circumstellar disk, Orion 114-426, made using NICMOS on the Hubble Space Telescope. Images taken against the bright nebular background of the ionized hydrogen Paα line at 1.87 μm show the major axis of the disk to be approximately 20% smaller than at 0.6 μm, from which we deduce the structure of the edge of the disk. Continuum images of diffuse polar lobes above and below the plane of the disk show a morphology and evolution with wavelength consistent with predictions for reflection nebulae in a diffuse envelope with large polar cavities, surrounding a thin, massless, Keplerian disk, centered on an otherwise hidden central star. We make use of our observations and reasonable assumptions about the underlying disk structure to show that the disk mass is at least 10 M⊕ and plausibly ≥5 × 10-4 M⊙. © 1998. The American Astronomical Society. All rights reserved.
• Mentzell, J. E., McIntosh, M. B., Schwenker, J. P., & Thompson, R. I. (1998). NICMOS cold-well displacement monitor: A portable Hubble simulator. Proceedings of SPIE - The International Society for Optical Engineering, 3354, 1044-1052.
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  Abstract: The anomalous motion of the near IR camera and multi-object spectrometer (NICMOS) detector arrays was originally discovered and characterized during ground optical testing, in a large, high fidelity Hubble Space Telescope (HST) simulator. To monitor the state of the cryo-mechanical system, as NICMOS traveled among several testing sties, a portable stimulus was needed. The cold-well displacement monitor (CDM) was quickly assembled from a very simple design. The 'cheaper, better, faster' approach proved to be a winner here. Off-the-shelf optics, a simplified interface to the instrument, and a limited set of requirements were used. After calibration against the large refractive aberration simulator/Hubble opto-mechanical simulator (RAS/HOMS), the CDM gave results of similar accuracy to RAS/HOMS. It became the primary tool for the difficult job of managing the NICMOS cryogen system up through launch. ©2003 Copyright SPIE - The International Society for Optical Engineering.
• Sahai, R., Hines, D. C., Kastner, J. H., Weintraub, D. A., Trauger, J. T., Rieke, M. J., Thompson, R. I., & Schneider, G. (1998). The structure of the prototype bipolar protoplanetary nebula CRL 2688 (EGG Nebula): Broadband, polarimetric, and H₂ line imaging with NICMOS on the Hubble Space Telescope. Astrophysical Journal Letters, 492(2 PART II), L163-L167.
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  Abstract: High-resolution near-infrared (1.65-2.1 μm) images and 2 μm polarimetric images of the inner 19′.5 × 19′.3 region of the bipolar protoplanetary nebula CRL 2688, taken with the newly installed Near-Infrared Camera and Multiobject Spectrometer (NICMOS) aboard the Hubble Space Telescope (HST), are reported. The NICMOS images reveal a wealth of structure also seen in HST Wide Field Planetary Camera 2 images but not detected in previous, ground-based near-infrared imaging studies. In particular, we detect a system of concentric arcs centered on, and twin "searchlight beams" emanating from, the obscured central star. The images also show two sharply bounded spindle-shaped polar cavities with point-symmetric structure, and the 2.122 μm H2 S(1) υ = 1-0 emission-line image clearly resolves the sharp interface between the high-velocity outflow that produces these polar cavities and the surrounding slow outflow that forms the extended nebula. The H2 image also resolves the bright equatorial H2 emission into distinct components and elucidates their detailed morphologies. We have discovered, within the dark lane that bifurcates the bipolar lobes of CRL 2688, a compact source of unpolarized light. Our imaging polarimetry shows that this source is not the post-asymptotic giant branch star that illuminates the nebula; we conclude that the compact source is a companion star. © 1998. The American Astronomical Society. All rights reserved.
• Schneider, G., Thompson, R. I., Smith, B. A., & Terrile, R. J. (1998). Exploration of the environments of nearby stars with the NICMOS coronagraph - instrumental performance considerations. Proceedings of SPIE - The International Society for Optical Engineering, 3356(1), 222-233.
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  Abstract: The Near Infrared Camera and Multi-Object Spectrometer (NICMOS), installed into the Hubble Space Telescope (HST) in February 1997, incorporates a coronagraphic imaging capability. The coronagraph is comprised of two optical elements. The camera 2 field divider mirror, upon which the HST f/24 input beam is imaged, includes a 170 μm diameter hole which contains approximately 93% of the encircled energy from a stellar Point Spread Function (PSF) at a wavelength of 1.6 μm. The coronagraphic hole lowers both the diffracted energy in the surrounding region by reducing the high spatial frequency components of the occulted core of the PSF, and down stream scattering. The geometrical radius of this occulting spot, when re-imaged through the camera 2 f/45 optics, is approximately 4 pixels (or 0.3″) at the detector focal plane. An oversized cold pupil-plane mask (maintained at approximately 100 K), with radial structures co-aligned with the HST secondary mirror spider, acts over the whole 19.1″×19.2″ field to further reduce the diffracted energy in the direction of the spider vanes. The absolute performance levels of the coronagraph were ascertained during the Servicing Mission Observatory Verification (SMOV) program. Using a differential imaging strategy (by rolling the spacecraft) we expect to achieve statistically significant detections of sub-stellar companions at 1.6 μm with a ΔH of approximately 10 and separations as close as 0.5″ (corresponding to 2.5AU at 5pc). The NICMOS Environments of Nearby Stars (EONS) programs is exploiting this capability in systematic surveys of nearby, and young stars searching for brown dwarfs and giant planets, and protoplanetary disks around main-sequence stars.
• Scoville, N. Z., Evans, A. S., Dinshaw, N., Thompson, R., Rieke, M., Schneider, G., Low, F. J., Hines, D., Stobie, B., Becklin, E., & Epps, H. (1998). NICMOS imaging of the nuclei of ARP 220. Astrophysical Journal Letters, 492(2 PART II), L107-L110.
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  Abstract: We report high-resolution imaging of the ultraluminous infrared galaxy Arp 220 at 1.1, 1.6, and 2.22 μm with the Near-Infrared Camera and Multiobject Spectrometer on the Hubble Space Telescope. The diffraction-limited images at 0″.1-0″.2 resolution clearly resolve both nuclei of the merging galaxy system and reveal for the first time a number of luminous star clusters in the circumnuclear envelope. The morphologies of both nuclei are strongly affected by dust obscuration, even at 2.2 μm: the primary nucleus (west) presents a crescent shape, concave to the south, and the secondary (eastern) nucleus is bifurcated by a dust lane with the southern component being very reddened. In the western nucleus, the morphology of the 2.2 μm emission is most likely the result of obscuration by an opaque disk embedded in the nuclear star cluster. The morphology of the central starburst cluster in the western nucleus is consistent with either a circumnuclear ring of star formation or a spherical cluster with the bottom half obscured by the embedded dust disk. Comparison of centimeter-wave radio continuum maps with the near-infrared images suggests that the radio nuclei lie in the dust disk on the west and near the highly reddened southern component of the eastern complex. The radio nuclei are separated by 0″.98 (corresponding to 364 pc at 77 Mpc), and the half-widths of the infrared nuclei are ∼0″.2-0″.5. At least eight unresolved infrared sources - probably globular clusters - are also seen in the circumnuclear envelope at radii of 2″-7″. Their near-infrared colors do not significantly constrain their ages. © 1998. The American Astronomical Society. All rights reserved.
• Stolovy, S. R., Burton, M. G., Erickson, E. F., Kaufman, M. J., Chrysostomou, A., Young, E. T., W., S., Axon, D. J., Thompson, R. I., Rieke, M. J., & Schneider, G. (1998). NICMOS 2 micron continuum and H₂ images of OMC-1. Astrophysical Journal Letters, 492(2 PART II), L151-L155.
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  Abstract: The core of OMC-1 has been imaged with the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) on board the Hubble Space Telescope at 0″.2 resolution in 1% filters at 2.12 and 2.15 μm, revealing intricate structures in both continuum and shocked molecular hydrogen line emission. Numerous H2-emitting clumps surrounding the BN/KL region have been resolved for the first time, several of which exhibit prototypical bowshock morphologies with V-shaped tips. We interpret these to be lower excitation analogs of similar structures ∼2′ northwest of the core observed with ground-based telescopes. Many of the elongated H2 structures and bowshock features appear to radiate outward from a region within a few arcseconds of radio source I, which suggests that the H2 energetics are dominated by one or more outflow sources in this region. However, the orientations of some features are unrelated to this apparent outflow pattern. The deeply embedded, suspected outflow source I remains undetected at 2 μm, although two faint new continuum sources have been detected within ∼1″ of it. The newly resolved H2 features with bow-shock morphologies are located in regions previously identified as bow shocks by highly blueshifted components in their line profiles. In contrast, regions of H2 emission that are diffuse in the NICMOS image have broad, smooth line profiles. Several continuum features have an arclike appearance, which suggests interactions of winds with the ambient medium. At least 40 stellar or protostellar continuum sources have been detected, including at least one proplyd and four pairs of binary stars. © 1998. The American Astronomical Society. All rights reserved.
• Thompson, R. I., & Schneider, G. (1998). NICMOS performance on the Hubble Space Telescope. Proceedings of SPIE - The International Society for Optical Engineering, 3356(1), 215-221.
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  Abstract: NICMOS, the Near Infrared Camera and Multi-Object Spectrometer was placed in the Hubble Space Telescope in February of 1997. Since then it has been carrying out and extensive program of scientific research. This paper presents the current status and performance of the instrument along with a sample of the observations that have been carried out to this date.
• Thompson, R. I., Corbin, M. R., Young, E., & Schneider, G. (1998). NGC 2264 IRS: Evidence for triggered star formation. Astrophysical Journal Letters, 492(2 PART II), L177-L179.
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  Abstract: As part of its commissioning process the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) obtained images of the infrared source NGC 2264 IRS, also known as Allen's source, in three colors. In addition to the completely overexposed image of IRS there are six point objects, never previously observed, at projected separations of 2″.6 to 4″.9 from IRS. These sources are interpreted as near solar mass, pre-main-sequence stars that may be the result of triggered star formation. Regardless of the star formation method, it appears certain that this group of stars is a coeval formation of various mass stars. This makes it a very valuable data set for the study of pre-main-sequence evolution. © 1998. The American Astronomical Society. All rights reserved.
• Thompson, R. I., Rieke, M., Schneider, G., Hines, D. C., & Corbin, M. R. (1998). Initial on-orbit performance of NICMOS. Astrophysical Journal Letters, 492(2 PART II), L95-L97.
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  Abstract: On 1997 February 13, Space Shuttle astronauts placed the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) into the Hubble Space Telescope. Following installation, the servicing mission orbital verification program (SMOV) performed extensive testing of the instrument to verify that it can be operated and calibrated effectively. This program is essentially completed, and routine science observations have begun in most of the NICMOS modes of operation. This Letter describes the performance levels of NICMOS at this time. © 1998. The American Astronomical Society. All rights reserved.
• Weymann, R. J., Stern, D., Bunker, A., Spinrad, H., Chaffee, F. H., Thompson, R. I., & Storrie-Lombardi, L. J. (1998). Keck spectroscopy and nicmos photometry of a redshift z = 5.60 galaxy. Astrophysical Journal Letters, 505(2 PART II), L95-L98.
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  Abstract: We present Keck Low Resolution Imaging Spectrometer spectroscopy along with Near-Infrared Camera and Multiobject Spectrometer (NICMOS) F110W (∼J) and F160W (∼H) images of the galaxy HDF 4-473.0 in the Hubble Deep Field (HDF), with a detection of an emission line consistent with Lyα at a redshift of z = 5.60. Attention to this object as a high-redshift galaxy was first drawn by Lanzetta, Yahil, & Fernandez-Soto and appeared in their initial list of galaxies with redshifts estimated from the Wide Field Planetary Camera 2 (WFPC2) HDF photometry. It was selected by us for spectroscopic observation, along with others in the HDF, on the basis of the NICMOS F110W and F160W and WFPC2 photometry. ForH0 = 65 km s-1 Mpc-1 and q0 = 0.125, the use of simple evolutionary models along with the F814W (∼I), F110W, and F160W magnitudes allow us to estimate the star formation rate (∼13 M⊙ yr-1). The colors suggest a reddening of E(B - V) ∼ 0.06. The measured flux in the Lyα line is approximately 1.0 × 10-17 ergs cm-2 s-1, and the rest-frame equivalent width, correcting for the absorption caused by intervening H I, is ∼90 Å. The galaxy is compact and regular, but resolved, with an observed FWHM of ∼0″.44. Simple evolutionary models can accurately reproduce the colors, and these models predict the Lyα flux to within a factor of 2. Using this object as a template shifted to higher redshifts, we calculate the magnitudes through the F814W and two NICMOS passbands for galaxies at redshifts 6 < z < 10. © 1998. The American Astronomical Socicly. All rights reserved.
• Thompson, R. (1997). Scientific results from NICMOS. Space Congress Proceedings.
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  Abstract: Observations with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) began soon after its insertion into the Hubble Space Telescope by STS-82 astronauts in February of 1997. The initial observations were mainly diagnostic with some Early Release Observations (EROs) to demonstrate the abilities of the instrument. This talk presents new observations since the epoch of the EROs along with new science findings from these observations. The author wishes to thank all of those who graciously contributed data for this presentation since most of these images are still in their proprietary period for release. The presentation will also touch on the future plans for the NICMOS project.
• Thompson, R. I. (1996). Si X forbidden emission in NGC 1068 and NGC 7469. Astrophysical Journal Letters, 459(2 PART II), L61-L63.
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  Abstract: This Letter presents the first observation of [Si X] emission in a celestial object other than the solar corona. The detected line at 1.430 μm is present in the spectra of both NGC 1068 and NGC 7469. The ionization potential of Si X is 401.4 eV, which makes this one of the highest ionization energy lines observed in active galactic nuclei. The line falls in a region of high telluric absorption that requires a fortuitous combination of redshift and abnormally dry observing conditions to observe. © 1996 The American Astronomical Society. All rights reserved. Printed in U.S.A.
• Thompson, R. I. (1995). High-resolution near-infrared spectra of NGC 4151: Line and continuum analysis. Astrophysical Journal Letters, 445(2), 700-711.
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  Abstract: This paper presents new high-resolution near-infrared spectra of the Seyfert 1.5 galaxy NGC 4151. These spectra are the first high-resolution infrared spectra of this galaxy that span the region from 0.87 to 2.5 μm. Analysis of the extensive [Fe II] emission yields electron temperatures and densities consistent with 104 K and 104 cm-3 for the Fe II emission-line regions. The high ratio of [Fe II] emission to hydrogen indicates that the majority of Fe is in gaseous form. Analysis of the H2 emission indicates that the emission is proably shock excited and that the H2 lines have narrower emission-line widths than the observed [S III] narrow-line emission. NGC 4151 appears to have been in a state of high continuum and broad line flux during the observation period; therefore, the equivalent width of some of the narrow line components is lower than in previous observations.
• Thompson, R. I., Rieke, M. J., Kormos, K. A., & Mentzell, J. E. (1995). Characterization of the NICMOS flight detectors and their capabilities. Proceedings of SPIE - The International Society for Optical Engineering, 2475, 367-375.
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  Abstract: The near infrared camera and multi-object spectrometer (NICMOS) is a new instrument for the Hubble Space Telescope (HST). NICMOS provides opportunities for near infrared astrophysical investigations with HST in the 0.8 - 2.5 μm spectral region with 256 × 256 array detectors of HgCdTe manufactured by the Rockwell International Electro-Optical Center. This manuscript describes the characteristics and capabilities of the flight focal plane assemblies (FPAs) for all three NICMOS cameras as well as the three flight spares and three continuous evaluation FPAs. All of the FPAs exceed the original specifications by a significant amount and represent the first scientific space flight of infrared arrays for this wavelength region.
• Thompson, R. I. (1994). NICMOS and its arrays - The near infrared camera and multi-object spectrometer. Experimental Astronomy, 3(1-4), 93-100.
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  Abstract: NICMOS is a second generation instrument for the Hubble Space Telescope to provide imaging and spectroscopic capabilities in the near infrared region. NICMOS utilizes HgCdTe detectors in three cameras, one with grisms, to image in the 0.8-2.5 mm spectral region. © 1994 Kluwer Academic Publishers.
• Thompson, R. I. (1994). The GRIS - The grating infrared spectrometer. Experimental Astronomy, 3(1-4), 193-194.
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  Abstract: The GRIS is a prism cross-dispersed spectrometer utilizing a NICMOS 3 detector array for moderate and high dispersion spectroscopy in the near infrared spectral region. The spectrometer is cryogenically cooled with liquid nitrogen and operates on the 2.3 m Steward Observatory Telescope. Initial use proves it to be an excellent tool for near infrared astrophysics. © 1994 Kluwer Academic Publishers.
• Thompson, R. I. (1993). NICMOS: A second generation infrared instrument for the hubble space telescope. Advances in Space Research, 13(12), 509-519.
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  Abstract: NICMOS (the Near Infrared Camera and Multi-Object Spectrometer) is a second generation scientific instrument for the Hubble Space Telescope (HST). Three cryogenic cameras with 256x256 HgCdTe arrays provide diffraction limited imaging throughout the 0.8 - 2.5 μm spectral region. Grisms in one of the cameras produces multi-object spectroscopy for all objects in the field. Coronagraphic and polarization capabilities round out the NICMOS modes of operation. Scheduled for launch on the second HST maintenance mission in 1997, NICMOS has a five year on-orbit cryogenic lifetime. © 1993.
• Thompson, R. (1992). NICMOS: Near Infrared Camera and Multi-Object Spectrometer. Space Science Reviews, 61(1-2), 69-93.
• Thompson, R. I. (1991). The near infrared camera and multiple objective spectrometer for the hubble space telescope. Advances in Space Research, 11(2), 295-300.
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  Abstract: NICMOS, the Near Infrared Camera and Multiple Objective Spectrometer, will be a key instrument for high redshift studies with the Hubble Space Telescope. The combination of high spatial resolution, low background, and very high detector sensitivity provides detection capabilities for objects, if present, to redshifts of 20 and beyond. In many cases definitive redshift measurements via detection of Lyman α line radiation is well within the NICMOS capabilities. NICMOS is an important cosmological tool connecting the HST visual and ultraviolet observations with the longer wavelength observations of cold telescopes such as COBE, ISO, and SIRTF. © 1991.
• Thompson, R. I., & Strittmatter, P. A. (1978). Circumstellar disks and planetary formation. The Moon and the Planets, 19(2), 207-210.
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  Abstract: The role of circumstellar disks in star and planetary formation is briefly reviewed. The observed disk around MWC 349 is used as an example and a table of evolutionary time scales and parameters is presented. The disk about MWC 349 is characteristic of that expected about a massive star. Disk structure about solar mass stars is more completely reviewed by Cameron (1978). The parameters for the disk indicate that there is a deduced region where conditions are appropriate for dust condensation and possible aggregation of material to planetary masses. For the purposes of the discussion we are assuming that the infrared as well as optical radiation arises from the disk which extends the 'known' extent of the disk to 1014cm. It is not yet certain that this is the case. © 1978 D. Reidel Publishing Company.
• Schnopper, H. W., & Thompson, R. I. (1974). 11. Fourier Spectrometers. Methods in Experimental Physics, 12(PART A), 491-529.
• Schnopper, H. W., Thompson, R. I., & Watt, S. (1968). Predicted performance of a rotating modulation collimator for locating celestial x-ray sources. Space Science Reviews, 8(4), 534-542.
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  Abstract: A method of determining the position of celestial X-ray sources which utilizes a modulation collimator rotating about a fixed axis is presented. The signal from each source in the field of view is modulated by a frequency which is fixed by the radial distance from the intersection of the rotation axis and the celestial sphere. The phase of the modulation is determined by the angular distance of the source from a reference line on the celestial sphere. Thus, the modulation function for each source is unique. The data are reduced by the technique of Fourier analysis. Synthesized experimental data for the cases of a single source and for five sources in the field of view are analysed. The ability to distinguish and accurately locate each source in a multiple source field is a major achievement of this method. Sources can be located with an accuracy which is competitive with other methods. An experiment based on this method can be lifted on an Aerobee 150 system. © 1968 D. Reidel Publishing Company.

Proceedings Publications

• Thompson, R. I. (2017, July). Fundamental constants as monitors of the uni. In 14th Marcell Grossmann Conference, 14, 3657-3663.
• Thompson, R. I. (2017, September). The Relation between Fundamental Constants and Particle Physics Parameters. In Varying Constants and Fundamental Cosmology, 3, 1-6.
• Hardegree-Ullman, K., McGraw, A. M., Towner, A. P., Walker-LaFollette, A., Robertson, A., Smith, C., Turner, J., Biddle, L. I., & Thompson, R. (2013, jun). The Benefits of Peer-Mentoring in Undergraduate Group Research Projects at The University of Arizona. In American Astronomical Society Meeting Abstracts, 222, #104.03.
• McGraw, A. M., Hardegree-Ullman, K., Turner, J., Shirley, Y. L., Walker-Lafollette, A., Scott, A., Guvenen, B., Raphael, B., Sanford, B., Smart, B., Nguyen, C., Jones, C., Smith, C., Cates, I., Romine, J., Cook, K., Pearson, K., Biddle, L., Small, L., , Donnels, M., et al. (2013, jan). Enhancing Astronomy Major Learning Through Group Research Projects. In American Astronomical Society Meeting Abstracts, 221, #255.08.
• Thompson, R. I. (2013, jan). Proton to Electron Mass Ratio Constraints on Cosmology and New Physics. In American Astronomical Society Meeting Abstracts, 221, #222.04.
• Thompson, R., Turner, J., Hardegree-Ullman, K., Raphael, B., Smith, C., Towner, A. P., Walker-LaFollette, A., Wallace, S., Berkson, E., & Greenwood, N. (2013, jan). Transit of Exoplanet WASP 24-b. In American Astronomical Society Meeting Abstracts, 221, #343.12.
• Thompson, R. I. (2012, may). Fundamental Constant Constraints on New Physics and Quintessence Models. In American Astronomical Society Meeting Abstracts #220, 220, #321.06.