Eduardo Rozo

Interests

Research

Cosmology

Teaching

Physics, Astronomy

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Scholarly Contributions

Journals/Publications

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  Clusters of galaxies are sensitive to the most nonlinear peaks in the cosmicdensity field. The weak gravitational lensing of background galaxies byclusters can allow us to infer their masses. However, galaxies associated withthe local environment of the cluster can also be intrinsically aligned due tothe local tidal gradient, contaminating any cosmology derived from the lensingsignal. We measure this intrinsic alignment in Dark Energy Survey (DES) Year 1redMaPPer clusters. We find evidence of a non-zero mean radial alignment ofgalaxies within clusters between redshift 0.1-0.7. We find a significantsystematic in the measured ellipticities of cluster satellite galaxies that weattribute to the central galaxy flux and other intracluster light. We attemptto correct this signal, and fit a simple model for intrinsic alignmentamplitude ($A_{\textrm{IA}}$) to the measurement, finding$A_{\textrm{IA}}=0.15\pm 0.04$, when excluding data near the edge of thecluster. We find a significantly stronger alignment of the central galaxy withthe cluster dark matter halo at low redshift and with higher richness andcentral galaxy absolute magnitude (proxies for cluster mass). This is animportant demonstration of the ability of large photometric data sets like DESto provide direct constraints on the intrinsic alignment of galaxies withinclusters. These measurements can inform improvements to small-scale modelingand simulation of the intrinsic alignment of galaxies to help improve theseparation of the intrinsic alignment signal in weak lensing studies.[Journal_ref: ]

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