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A highly obscured and strongly clustered galaxy population discovered with the Spitzer Space Telescope

Magliocchetti, M. and Silva, L. and Lapi, A. and De Zotti, G. and Granato, G. L. and Fadda, D. and Danese, L. (2007) A highly obscured and strongly clustered galaxy population discovered with the Spitzer Space Telescope. Monthly Notices of the Royal Astronomical Society, 375 (4). pp. 1121-1132. ISSN 0035-8711.

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The ~800 optically unseen (R > 25.5) 24-μm selected sources in the complete Spitzer First Look Survey sample with F_(24 μm) ≥ 0.35 mJy are found to be very strongly clustered. If, as indicated by several lines of circumstantial evidence, they are ultraluminous far-infrared galaxies at z ≃ 1.6–2.7 , the amplitude of their spatial correlation function is very high. The associated comoving clustering length is estimated to be r_0 = 14.0^(+2.1)_(−2.4) Mpc, value which puts these sources amongst the most strongly clustered populations of our known Universe. Their 8–24 μm colours suggest that the active galactic nucleus contribution dominates above F_(24 μm) ≃ 0.8 mJy , consistent with earlier analyses. The properties of these objects (number counts, redshift distribution, clustering amplitude) are fully consistent with those of proto-spheroidal galaxies in the process of forming most of their stars and of growing their active nucleus, as described by the Granato et al. model. In particular, the inferred space density of such galaxies at z ≃ 2 is much higher than what is expected from most semi-analytic models. Matches of the observed projected correlation function w(θ) with models derived within the so-called halo occupation scenario show that these sources have to be hosted by haloes more massive than ≃10^(13.4) M_⊙ . This value is significantly higher than that for the typical galactic haloes hosting massive elliptical galaxies, suggesting a duration of the starburst phase of massive high-redshift dusty galaxies of T_B ~ 0.5 Gyr.

Item Type:Article
Related URLs:
URLURL TypeDescription
De Zotti, G.0000-0003-2868-2595
Fadda, D.0000-0002-3698-7076
Additional Information:© 2007 The Authors. Journal compilation © 2007. Accepted 2006 November 27. Received 2006 November 21; in original form 2006 August 3. Thanks are due to the referee for constructive comments that helped improving the paper. Work supported in part by MIUR and ASI.
Funding AgencyGrant Number
Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: statistics; cosmology: observations; cosmology: theory; large-scale structure of Universe; infrared: galaxies
Issue or Number:4
Record Number:CaltechAUTHORS:20100423-094903344
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18055
Deposited By: Jason Perez
Deposited On:23 Apr 2010 18:03
Last Modified:09 Mar 2020 13:18

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