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The COSMOS2015 galaxy stellar mass function: Thirteen billion years of stellar mass assembly in ten snapshots

Davidzon, I. and Ilbert, O. and Laigle, C. and Coupon, J. and McCracken, H. J. and Delvecchio, I. and Masters, D. and Capak, P. and Hsieh, B. C. and Le Fèvre, O. and Tresse, L. and Béthermin, M. and Chang, Y.-Y. and Faisst, A. L. and Le Floc'h, E. and Steinhardt, C. and Toft, S. and Aussel, H. and Dubois, C. and Hasinger, G. and Salvato, M. and Sanders, D. B. and Scoville, N. and Silverman, J. D. (2017) The COSMOS2015 galaxy stellar mass function: Thirteen billion years of stellar mass assembly in ten snapshots. Astronomy and Astrophysics, 605 . Art. No. A70. ISSN 0004-6361. doi:10.1051/0004-6361/201730419.

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We measure the stellar mass function (SMF) and stellar mass density of galaxies in the COSMOS field up to z ~ 6. We select them in the near-IR bands of the COSMOS2015 catalogue, which includes ultra-deep photometry from UltraVISTA-DR2, SPLASH, and Subaru/Hyper Suprime-Cam. At z > 2.5 we use new precise photometric redshifts with error σ_z = 0.03(1 + z) and an outlier fraction of 12%, estimated by means of the unique spectroscopic sample of COSMOS (~100 000 spectroscopic measurements in total, more than one thousand having robust z_(spec)> 2.5). The increased exposure time in the DR2, along with our panchromatic detection strategy, allow us to improve the completeness at high z with respect to previous UltraVISTA catalogues (e.g. our sample is >75% complete at 10^(10)M⊙ and z = 5). We also identify passive galaxies through a robust colour–colour selection, extending their SMF estimate up to z = 4. Our work provides a comprehensive view of galaxy-stellar-mass assembly between z = 0.1 and 6, for the first time using consistent estimates across the entire redshift range. We fit these measurements with a Schechter function, correcting for Eddington bias. We compare the SMF fit with the halo mass function predicted from ΛCDM simulations, finding that at z > 3 both functions decline with a similar slope in thehigh-mass end. This feature could be explained assuming that mechanisms quenching star formation in massive haloes become less effective at high redshifts; however further work needs to be done to confirm this scenario. Concerning the SMF low-mass end, it shows a progressive steepening as it moves towards higher redshifts, with α decreasing from -1.47^(+0.02)_(-0.02) at z ≃ 0.1 to -2.11^(+0.30)_(-0.13) at z ≃ 5. This slope depends on the characterisation of the observational uncertainties, which is crucial to properly remove the Eddington bias. We show that there is currently no consensus on the method to quantify such errors: different error models result in different best-fit Schechter parameters.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Davidzon, I.0000-0002-2951-7519
Ilbert, O.0000-0002-7303-4397
McCracken, H. J.0000-0002-9489-7765
Delvecchio, I.0000-0001-8706-2252
Masters, D.0000-0001-5382-6138
Capak, P.0000-0003-3578-6843
Hsieh, B. C.0000-0001-5615-4904
Le Fèvre, O.0000-0001-5891-2596
Béthermin, M.0000-0002-3915-2015
Chang, Y.-Y.0000-0002-6441-980X
Faisst, A. L.0000-0002-9382-9832
Steinhardt, C.0000-0003-3780-6801
Toft, S.0000-0003-3631-7176
Aussel, H.0000-0002-1371-5705
Hasinger, G.0000-0002-0797-0646
Salvato, M.0000-0001-7116-9303
Sanders, D. B.0000-0002-1233-9998
Scoville, N.0000-0002-0438-3323
Silverman, J. D.0000-0002-0000-6977
Alternate Title:The COSMOS2015 galaxy stellar mass function: 13 billion years of stellar mass assembly in 10 snapshots
Additional Information:© 2017 ESO. Article published by EDP Sciences. Received 10 January 2017; Accepted 17 May 2017; Published online 12 September 2017. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme 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 data produced by the SPLASH team from observations made with the Spitzer Space Telescope ( The authors warmly thank the anonymous referee for her/his constructive comments. The authors thank Shoubaneh Hemmati and Hooshang Nayyeri for providing us with the CANDELS Multiwavelength Catalog in the COSMOS field, and Andrea Grazian and Thibault Garel for sending their results in a convenient digitalised format. I.D. thanks Marta Volonteri, Jeremy Blaizot, Yohan Dubois, Andrea Grazian, Roberto Maiolino for very useful discussions. I.D. and O.I. acknowledge funding of the French Agence Nationale de la Recherche for the SAGACE project. C.L. acknowledges support from a Beecroft fellowship. I.D. acknowledges the European Union’s Seventh Framework programme under grant agreement 337595 (ERC Starting Grant, “CoSMass”). A.F. acknowledges support from the Swiss National Science Foundation. The COSMOS team in France acknowledges support from the Centre National d’Études Spatiales.
Group:COSMOS, SPLASH, Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)UNSPECIFIED
Beecroft fellowshipUNSPECIFIED
European Research Council (ERC)337595
Swiss National Science Foundation (SNSF)UNSPECIFIED
Centre National d’Études Spatiales (CNES)UNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: luminosity function, mass function – galaxies: statistics – galaxies: high-redshift
Record Number:CaltechAUTHORS:20170628-140248161
Persistent URL:
Official Citation:The COSMOS2015 galaxy stellar mass function - Thirteen billion years of stellar mass assembly in ten snapshots I. Davidzon, O. Ilbert, C. Laigle, J. Coupon, H. J. McCracken, I. Delvecchio, D. Masters, P. Capak, B. C. Hsieh, O. Le Fèvre, L. Tresse, M. Bethermin, Y.-Y. Chang, A. L. Faisst, E. Le Floc’h, C. Steinhardt, S. Toft, H. Aussel, C. Dubois, G. Hasinger, M. Salvato, D. B. Sanders, N. Scoville and J. D. Silverman A&A, 605 (2017) A70 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78661
Deposited By: Joy Painter
Deposited On:28 Jun 2017 21:13
Last Modified:15 Nov 2021 17:42

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