COLOR DISTRIBUTIONS, NUMBER, AND MASS DENSITIES OF MASSIVE GALAXIES AT 1.5 < z < 3: COMPARING OBSERVATIONS WITH MERGER SIMULATIONS

Journal Article · Mon Jul 20 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/700/1/799; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21313858

Wuyts, Stijn; Cox, Thomas J; Hayward, Christopher C; Hernquist, Lars ^[1]; Franx, Marijn ^[2]; Foerster Schreiber, Natascha M ^[3]; Hopkins, Philip F ^[4]; Labbe, Ivo ^[5]; Marchesini, Danilo; Van Dokkum, Pieter G ^[6]; Robertson, Brant E ^[7]; Toft, Sune ^[8]

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1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
2. Leiden University, Leiden Observatory, P.O. Box 9513, NL-2300 RA, Leiden (Netherlands)
3. MPE, Giessenbackstrasse, D-85748 Garching (Germany)
4. Department of Astronomy, University of California Berkeley, Berkeley, CA 94720 (United States)
5. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
6. Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States)
7. Kavli Institute for Cosmological Physics, and Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
8. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Muenchen (Germany)

We present a comparison between the observed color distribution, number, and mass density of massive galaxies at 1.5 < z < 3 and a model by Hopkins et al. that relates the quasar and galaxy population on the basis of gas-rich mergers. In order to test the hypothesis that quiescent red galaxies are formed after a gas-rich merger involving quasar activity, we confront photometry of massive (M>4 x 10{sup 10} M{sub sun}) galaxies extracted from the FIRES, GOODS-South, and MUSYC surveys, together spanning an area of 496 arcmin{sup 2}, with synthetic photometry from hydrodynamical merger simulations. As in the Hopkins et al. model, we use the observed quasar luminosity function to estimate the merger rate. We find that the synthetic U - V and V - J colors of galaxies that had a quasar phase in their past match the colors of observed galaxies that are best characterized by a quiescent stellar population. At z {approx} 2.6, the observed number and mass density of quiescent red galaxies with M>4 x 10{sup 10} M{sub sun} is consistent with the model in which every quiescent massive galaxy underwent a quasar phase in the past. At z {approx} 1.9, 2.8 times less quiescent galaxies are observed than predicted by the model as descendants of higher redshift quasars. The merger model also predicts a large number and mass density of galaxies undergoing star formation driven by the merger. We find that the predicted number and mass density accounts for 30%-50% of the observed massive star-forming galaxies. However, their colors do not match those of observed star-forming galaxies. In particular, the colors of dusty red galaxies (accounting for 30%-40% of the massive galaxy population) are not reproduced by the simulations. Several possible origins of this discrepancy are discussed. The observational constraints on the validity of the model are currently limited by cosmic variance and uncertainties in stellar population synthesis and radiative transfer.

• OSTI ID: 21313858
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 700; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
COLOR
GALACTIC EVOLUTION
GALAXIES
LUMINOSITY
MASS
PHOTOMETRY
QUASARS
RADIANT HEAT TRANSFER
RED SHIFT
SIMULATION
STARS