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The Mass Assembly History of Spheroidal Galaxies: Did Newly Formed Systems Arise via Major Mergers?

Bundy, Kevin and Treu, Tommaso and Ellis, Richard S. (2007) The Mass Assembly History of Spheroidal Galaxies: Did Newly Formed Systems Arise via Major Mergers? Astrophysical Journal Letters, 665 (1). L5-L8. ISSN 2041-8205.

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We examine the properties of a morphologically selected sample of 0.4 < z < 1.0 spheroidal galaxies in the GOODS fields in order to ascertain whether or not their increase in abundance with time arises primarily from major mergers. To address this question, we determine the scaling relations between the dynamical mass M_(dyn), determined from stellar velocity dispersions, and the stellar mass M_*, determined from optical and infrared photometry. We exploit these relations across the larger sample for which we have stellar masses in order to construct the first statistically robust estimate of the evolving dynamical mass function (MF) over 0 < z < 1. The trends observed match those seen in the stellar mass functions of Bundy et al. regarding the top-down growth in the abundance of spheroidal galaxies. By referencing our dynamical masses to the halo virial mass, M_(vir), we compare the growth rate in the abundance of spheroidals to that predicted by the assembly of dark matter halos. Our comparisons demonstrate that major mergers do not fully account for the appearance of new spheroidals since z ~ 1 and that additional mechanisms, such as morphological transformations, are required to drive the observed evolution.

Item Type:Article
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URLURL TypeDescription
Bundy, Kevin0000-0001-9742-3138
Treu, Tommaso0000-0002-8460-0390
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2007 The American Astronomical Society. Received 2007 March 13; accepted 2007 June 27; published 2007 July 27. We are very grateful to Simon White and Volker Springel for help in deriving results from the Millennium Run Database, and we also thank Raphael Gavazzi, Andrew Benson, Phil Hopkins, and Karl Glazebrook for useful discussions. R. S. E. acknowledges the hospitality of Ray Carlberg at the University of Toronto during a sabbatical visit, and T. T. acknowledges support from a Sloan Research Fellowship.
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Subject Keywords:galaxies : elliptical and lenticular, cD; galaxies : evolution; galaxies : kinematics and dynamics; galaxies : luminosity function, mass function
Issue or Number:1
Record Number:CaltechAUTHORS:20091027-083902954
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Official Citation:The Mass Assembly History of Spheroidal Galaxies: Did Newly Formed Systems Arise via Major Mergers? Kevin Bundy, Tommaso Treu, and Richard S. Ellis 2007 ApJ 665 L5-L8 doi: 10.1086/519526
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16485
Deposited By: Tony Diaz
Deposited On:29 Oct 2009 21:15
Last Modified:23 Nov 2019 00:22

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