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Compact high-redshift galaxies are the cores of the most massive present-day spheroids

Hopkins, Philip F. and Bundy, Kevin and Murray, Norman and Quataert, Eliot and Lauer, Tod R. and Ma, Chung-Pei (2009) Compact high-redshift galaxies are the cores of the most massive present-day spheroids. Monthly Notices of the Royal Astronomical Society, 398 (2). pp. 898-910. ISSN 0035-8711.

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Observations suggest that the effective radii of high-redshift massive spheroids are as much as a factor of ∼6 smaller than low-redshift galaxies of comparable mass. Given the apparent absence of low-redshift counterparts, this has often been interpreted as indicating that the high-density, compact red galaxies must be ‘puffed up’ by some mechanism. We compare the ensemble of high-redshift observations with large samples of well-observed, low-redshift ellipticals. At the same physical radii, the stellar surface mass densities of low- and high-redshift systems are comparable. Moreover, the abundance of high surface density material at low redshift is comparable to or larger than that observed at z > 1–2, consistent with the continuous buildup of spheroids over this time. The entire population of compact, high-redshift red galaxies may be the progenitors of the high-density cores of present-day ellipticals, with no need for a decrease in stellar density from z= 2 to 0. The primary difference between low- and high-redshift systems is thus the observed low-density material at large radii in low-redshift spheroids (rather than the high-density material in high-redshift spheroids). Such low-density material may either (1) assemble at z < 2 or (2) be present, but not yet detected, at z > 2. Mock observations of low-redshift massive systems suggest that the amount of low-density material at high redshifts is indeed significantly less than that at z= 0. However, deeper observations will be important in constraining the exact amount (or lack thereof) and distribution of this material, and how it builds up with redshift. We show that, without deep observations, the full extent of such material even at low redshifts can be difficult to determine, in particular if the mass profile is not exactly a single Sersic profile. We discuss the implications of our results for physical models of galaxy evolution.

Item Type:Article
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URLURL TypeDescription Paper
Hopkins, Philip F.0000-0003-3729-1684
Bundy, Kevin0000-0001-9742-3138
Quataert, Eliot0000-0001-9185-5044
Additional Information:© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 May 15. Received 2009 May 14; in original form 2009 March 4. We thank Todd Thompson, Ignacio Trujillo, Chien Peng, Pieter van Dokkum and Marijn Franx for helpful discussions. We also thank the anonymous referee for comments and suggestions regarding the treatment of observational effects. Support for PFH was provided by the Miller Institute for Basic Research in Science, University of California Berkeley. EQ is supported in part by NASA grant NNG06GI68G and the David and Lucile Packard Foundation.
Funding AgencyGrant Number
Miller Institute for Basic Research in ScienceUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:galaxies: active, galaxies: elliptical and lenticular, cD, galaxies: evolution, galaxies: formation, cosmology: theory
Issue or Number:2
Record Number:CaltechAUTHORS:20200521-163329967
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Official Citation:Philip F. Hopkins, Kevin Bundy, Norman Murray, Eliot Quataert, Tod R. Lauer, Chung-Pei Ma, Compact high-redshift galaxies are the cores of the most massive present-day spheroids, Monthly Notices of the Royal Astronomical Society, Volume 398, Issue 2, September 2009, Pages 898–910,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103392
Deposited By: George Porter
Deposited On:22 May 2020 18:27
Last Modified:22 May 2020 18:27

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