Caputi, K. I. and Ilbert, O. and Laigle, C. and McCracken, H. J. and Le Fèvre, O. and Fynbo, J. and Milvang-Jensen, B. and Capak, P. and Salvato, M. and Taniguchi, Y. (2015) Spitzer bright, UltraVISTA faint sources in COSMOS: the contribution to the overall population of massive galaxies at z = 3-7. Astrophysical Journal, 810 (1). Art. No. 73. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20150714-110504040
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We have analysed a sample of 574 Spitzer 4.5 μm-selected galaxies with [4.5] < 23 and K_s^(auto) > 24 (AB) over the UltraVISTA ultra-deep COSMOS field. Our aim is to investigate whether these mid-IR bright, near-IR faint sources contribute significantly to the overall population of massive galaxies at redshifts z ≥ 3. By performing a spectral energy distribution (SED) analysis using up to 30 photometric bands, we have determined that the redshift distribution of our sample peaks at redshifts z ≈ 2.5 − 3.0, and ~ 32% of the galaxies lie at z ≥ 3. We have studied the contribution of these sources to the galaxy stellar mass function (GSMF) at high redshifts. We found that the [4.5] < 23, K_s^(auto) > 24 galaxies produce a negligible change to the GSMF previously determined for K_s^(auto) < 24 sources at 3 ≤ z < 4, but their contribution is more important at 4 ≤ z < 5, accounting for > ≳ 50% of the galaxies with stellar masses M_(st) ≳ 6 × 10^(10)M⊙. We also constrained the GSMF at the highest-mass end (M_(st) ≳ 2 × 10^(11)M⊙) at z ≥ 5. From their presence at 5 ≤ z < 6, and virtual absence at higher redshifts, we can pinpoint quite precisely the moment of appearance of the first most massive galaxies as taking place in the ~ 0.2Gyr of elapsed time between z ~ 6 and z ~ 5. Alternatively, if very massive galaxies existed earlier in cosmic time, they should have been significantly dust-obscured to lie beyond the detection limits of current, large-area, deep near-IR surveys.
|Additional Information:||© 2015 The American Astronomical Society. Received 2015 May 18; accepted 2015 July 27; published 2015 September 1. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO program ID 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. Based on observations carried out with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA; the NASA/ESA Hubble Space Telescope, obtained and archived at the Space Telescope Science Institute; and the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. O.I. acknowledges funding from the French Agence Nationale de la Recherche (ANR) for the project SAGACE. B.M.-J. and J.F. acknowledge support from the ERC-StG grant EGGS-278202. The Dark Cosmology Centre is funded by the DNRF. We thank Kenneth Duncan, Yu Lu, and Paola Santini for providing us data in electronic format; Rebecca Bowler for performing photometric tests; and Yu Lu for useful discussions. We also thank an anonymous referee for a constructive report.|
|Group:||COSMOS, Infrared Processing and Analysis Center (IPAC)|
|Subject Keywords:||infrared: galaxies - galaxies: high-redshift - galaxies: evolution|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||15 Jul 2015 00:06|
|Last Modified:||27 Oct 2015 16:04|
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