The contribution of very massive high-redshift SWIRE galaxies to the stellar mass function

December 2007 • 2007A&A...476..151B

Authors • Berta, S. • Lonsdale, C. J. • Polletta, M. • Savage, R. S. • Franceschini, A. • Buttery, H. • Cimatti, A. • Dias, J. • Feruglio, C. • Fiore, F. • Held, E. V. • La Franca, F. • Maiolino, R. • Marconi, A. • Matute, I. • Oliver, S. J. • Ricciardelli, E. • Rubele, S. • Sacchi, N. • Shupe, D. • Surace, J.

Abstract • Context: In the last couple of years a population of very massive (M_star>10¹¹ M_⊙), high-redshift (z≥2) galaxies has been identified, but its role in galaxy evolution has not yet been fully understood.
Aims: It is necessary to perform a systematic study of high-redshift massive galaxies, in order to determine the shape of the very massive tail of the stellar mass function and determine the epoch of their assembly.
Methods: We selected high-z massive galaxies at 5.8 μm, in the SWIRE ELAIS-S1 field (1 deg^2). Galaxies with the 1.6 μm stellar peak redshifted into the IRAC bands (z≃1-3, called “IR-peakers”) were identified. Stellar masses were derived by means of spectro-photometric fitting and used to compute the stellar mass function (MF) at z = 1-2 and 2-3. A parametric fit to the MF was performed, based on a Bayesian formalism, and the stellar mass density of massive galaxies above z = 2 determined.
Results: We present the first systematic study of the very-massive tail of the galaxy stellar mass function at high redshift. A total of 326 sources were selected. The majority of these galaxies have stellar masses in excess of 10¹¹ M_⊙ and lie at z > 1.5. The availability of mid-IR data turned out to be a valuable tool to constrain the contribution of young stars to galaxy SEDs, and thus their M_star/L ratio. The influence of near-IR data and of the chosen stellar library on the SED fitting are also discussed. The z = 2-3 stellar mass function between 10¹¹ and 10¹² M_⊙ is probed with unprecedented detail. A significant evolution is found not only for galaxies with M 10¹¹ M_⊙, but also in the highest mass bins considered. The comoving number density of these galaxies was lower by more than a factor of 10 at z = 2-3, with respect to the local estimate. SWIRE 5.8 μm peakers more massive than 1.6 × 10¹¹ M_⊙ provide 30-50% of the total stellar mass density in galaxies at z = 2-3.

Links

• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2007A%26A...476..151B
• PREPRINT http://arxiv.org/abs/0710.0300
• POSTSCRIPT https://www.aanda.org/10.1051/0004-6361:20077491/postscript
• ELECTR http://www.aanda.org/htbin/resolve?bibcode=2007A%26A...476..151BFUL
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2007A%26A...476..151B
• PDF https://www.aanda.org/10.1051/0004-6361:20077491/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/476/151
• DATA http://archive.eso.org/bin/ads2eso?2007A%26A...476..151B
• DATA https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/476/151
• DATA https://irsa.ipac.caltech.edu/bibdata/2007/B/2007A&A...476..151B.html
• SPIRES http://inspirehep.net/search?p=find+eprint+arXiv:0710.0300