A highly obscured and strongly clustered galaxy population discovered with the Spitzer Space Telescope
Abstract
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.
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.Attached Files
Published - MAGmnras07.pdf
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Additional details
- Eprint ID
- 18055
- Resolver ID
- CaltechAUTHORS:20100423-094903344
- Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)
- Agenzia Spaziale Italiana (ASI)
- Created
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2010-04-23Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field