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Preprocessing among the Infalling Galaxy Population of EDisCS Clusters

Kirby, Matthew; Just, Dennis W.; Zaritsky, Dennis; Rudnick, Gregory; Desjardins, Tyler; Cool, Richard; Moustakas, John; Clowe, Douglas; Lucia, Gabriella De; Aragón-Salamanca, Alfonso; Desai, Vandana; Finn, Rose; Halliday, Claire; Jablonka, Pascale; Mann, Justin; Poggianti, Bianca; Bian, Fu-Yan; Liebst, Kelley

Authors

Matthew Kirby

Dennis W. Just

Dennis Zaritsky

Gregory Rudnick

Tyler Desjardins

Richard Cool

John Moustakas

Douglas Clowe

Gabriella De Lucia

Alfonso Aragón-Salamanca

Vandana Desai

Rose Finn

Claire Halliday

Pascale Jablonka

Justin Mann

Bianca Poggianti

Fu-Yan Bian

Kelley Liebst



Abstract

We present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4 < z < 0.8 selected from the ESO Distant Cluster Survey. We measured spectra using the low-dispersion prism in IMACS on the Magellan Baade telescope and calculate redshifts with an accuracy of σ z = 0.007. We find 1763 galaxies that are brighter than R = 22.9 in the large-scale cluster environs. We identify the galaxies expected to be accreted by the clusters as they evolve to z = 0 using spherical infall models and find that ~30%–70% of the z = 0 cluster population lies outside the virial radius at z ~ 0.6. For analogous clusters at z = 0, we calculate that the ratio of galaxies that have fallen into the clusters since z ~ 0.6 to those that were already in the core at that redshift is typically between ~0.3 and 1.5. This wide range of ratios is due to intrinsic scatter and is not a function of velocity dispersion, so a variety of infall histories is to be expected for clusters with current velocity dispersions of 300 km s−1 lesssim σ lesssim 1200 km s−1. Within the infall regions of z ~ 0.6 clusters, we find a larger red fraction of galaxies than in the field and greater clustering among red galaxies than blue. We interpret these findings as evidence of "preprocessing," where galaxies in denser local environments have their star formation rates affected prior to their aggregation into massive clusters, although the possibility of backsplash galaxies complicates the interpretation.

Journal Article Type Article
Publication Date Nov 1, 2019
Journal The Astrophysical Journal
Print ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 885
Issue 1
Article Number 6
APA6 Citation Kirby, M., Just, D. W., Zaritsky, D., Rudnick, G., Desjardins, T., Cool, R., …Liebst, K. (2019). Preprocessing among the Infalling Galaxy Population of EDisCS Clusters. Astrophysical Journal, 885(1), https://doi.org/10.3847/1538-4357/ab44a0
DOI https://doi.org/10.3847/1538-4357/ab44a0
Keywords Space and Planetary Science; Astronomy and Astrophysics
Publisher URL https://iopscience.iop.org/article/10.3847/1538-4357/ab44a0

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