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High-redshift elliptical galaxies: are they (all) really compact?

Mancini, C. and Daddi, E. and Renzini, A. and Salmi, F. and McCracken, H. J. and Cimatti, A. and Onodera, M. and Salvato, M. and Koekemoer, A. M. and Aussel, H. and Le Floc'h, E. and Willott, C. and Capak, P. (2010) High-redshift elliptical galaxies: are they (all) really compact? Monthly Notices of the Royal Astronomical Society, 401 (2). pp. 933-940. ISSN 0035-8711. doi:10.1111/j.1365-2966.2009.15728.x.

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We investigate the properties of 12 ultramassive passively evolving early-type galaxies (ETGs) at z_(phot) > 1.4 in the COSMOS 2 deg^2 field. These 12 ETGs were selected as pBzKs, have accurate 1.4 ≲ z_(phot) ≲ 1.7, high Sérsic index profiles typical of ellipticals, no detection at 24 μm, resulting in a complete ETG sample at M* > 2.5 × 10^(11) M_⊙ (Chabrier initial mass function). Contrary to the previous claims, the half-light radii estimated in very high signal-to-noise ratio imaging data from Hubble Space Telescope+Advanced Camera for Surveys (ACS) are found to be large for most of the sample, consistent with local ellipticals. If the high-redshift ETGs with M* < 2.5 × 10^(11) M_⊙ are really small in size and compact as reported in the previous studies, our result may suggest a 'downsizing' scenario, whereby the most massive ETGs reach their final structure earlier and faster than the lower mass ones. However, simulating galaxies with morphological properties fixed to those of local ETGs with the same stellar mass show that the few compact galaxies that we still recover in our sample can be understood in terms of fluctuations due to noise preventing the recovery of the extended low surface brightness haloes in the light profile. Such haloes, typical of Sérsic profiles, extending even up to 40 kpc, are indeed seen in our sample.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mancini, C.0000-0002-4297-0561
Daddi, E.0000-0002-3331-9590
Renzini, A.0000-0002-7093-7355
McCracken, H. J.0000-0002-9489-7765
Salvato, M.0000-0001-7116-9303
Koekemoer, A. M.0000-0002-6610-2048
Aussel, H.0000-0002-1371-5705
Willott, C.0000-0002-4201-7367
Capak, P.0000-0003-3578-6843
Additional Information:© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 September 16; received 2009 September 7; in original form 2009 July 10. We wish to thank Swara Ravindranath and Paolo Cassata for useful discussions. This work has been supported by grants ASI/COFIS/WP3110+WP3400 I/026/07/0. CM, ED, FS, HJM and MO acknowledge funding support of French ANR under contracts ANR-07-BLAN-0228 and ANR-08-JCJC-0008, and CM thanks CEA Saclay for hospitality and funding at the beginning of this work.
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)WP3110+WP3400 I/026/07/0
Agence Nationale pour la Recherche (ANR)ANR-07-BLAN-0228
Agence Nationale pour la Recherche (ANR)ANR-08-JCJC-0008
Subject Keywords:galaxies: evolution; galaxies: formation; galaxies: elliptical and lenticular, cD; galaxies: high-redshift
Issue or Number:2
Record Number:CaltechAUTHORS:20100208-152305495
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17423
Deposited On:09 Feb 2010 19:46
Last Modified:08 Nov 2021 23:35

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