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Preprocessing among the Infalling Galaxy Population of EDisCS Clusters

Just, Dennis W. and Kirby, Matthew and Zaritsky, Dennis and Rudnick, Gregory and Desjardins, Tyler and Cool, Richard and Moustakas, John and Clowe, Douglas and De Lucia, Gabriella and Aragón-Salamanca, Alfonso and Desai, Vandana and Finn, Rose and Halliday, Claire and Jablonka, Pascale and Mann, Justin and Poggianti, Bianca and Bian, Fu-Yan and Liebst, Kelley (2019) Preprocessing among the Infalling Galaxy Population of EDisCS Clusters. Astrophysical Journal, 885 (1). Art. No. 6. ISSN 1538-4357. doi:10.3847/1538-4357/ab44a0.

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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 ≾ σ ≾ 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Just, Dennis W.0000-0001-8580-630X
Kirby, Matthew0000-0002-4788-200X
Zaritsky, Dennis0000-0002-5177-727X
Rudnick, Gregory0000-0001-5851-1856
Aragón-Salamanca, Alfonso0000-0001-8215-1256
Desai, Vandana0000-0002-1340-0543
Finn, Rose0000-0001-8518-4862
Poggianti, Bianca0000-0001-8751-8360
Additional Information:© 2019 The American Astronomical Society. Received 2018 September 4; revised 2019 September 5; accepted 2019 September 12; published 2019 October 24. We thank an anonymous referee for insightful comments that have improved the content and presentation of this paper. D.W.J. and D.Z. acknowledge financial support from NASA LTSA award NNG05GE82G and GALEX grant NNX11AI47G. G.D.L. acknowledges financial support from the European Research Council under European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 202781. P.J. acknowledges support by the Swiss National Science Foundation (SNSF).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)202781
Swiss National Science Foundation (SNSF)UNSPECIFIED
Subject Keywords:galaxies: distances and redshifts – galaxies: evolution – galaxies: interactions
Issue or Number:1
Record Number:CaltechAUTHORS:20191028-081952139
Persistent URL:
Official Citation:Dennis W. Just et al 2019 ApJ 885 6
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99478
Deposited By: Tony Diaz
Deposited On:28 Oct 2019 16:36
Last Modified:16 Nov 2021 17:46

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