THE STAR FORMATION HISTORIES OF z {approx} 2 DUST-OBSCURED GALAXIES AND SUBMILLIMETER-SELECTED GALAXIES

Journal Article · Tue Jan 10 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/744/2/150· OSTI ID:22004204

Bussmann, R S ^[1]; Dey, Arjun; Jannuzi, B T ^[2]; Armus, L; Desai, V; Soifer, B T ^[3]; Brown, M J. I. ^[4]; Gonzalez, A H ^[5]; Melbourne, J ^[6]

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1. Harvard-Smithsonian Center for Astrophysics, 160 Concord Avenue, Cambridge, MA 02138 (United States)
2. National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)
3. Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States)
4. School of Physics, Monash University, Clayton, Victoria 3800 (Australia)
5. Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States)
6. Division of Physics, Math and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

The Spitzer Space Telescope has identified a population of ultraluminous infrared galaxies (ULIRGs) at z {approx} 2 that may play an important role in the evolution of massive galaxies. We measure the stellar masses (M{sub *}) of two populations of Spitzer-selected ULIRGs that have extremely red R - [24] colors (dust-obscured galaxies, or DOGs) and compare our results with submillimeter-selected galaxies (SMGs). One set of 39 DOGs has a local maximum in their mid-infrared (mid-IR) spectral energy distribution (SED) at rest frame 1.6 {mu}m associated with stellar emission ({sup b}ump DOGs{sup )}, while the other set of 51 DOGs have power-law mid-IR SEDs that are typical of obscured active galactic nuclei ({sup p}ower-law DOGs{sup )}. We measure M{sub *} by applying Charlot and Bruzual stellar population synthesis models to broadband photometry in the rest-frame ultraviolet, optical, and near-infrared of each of these populations. Assuming a simple stellar population and a Chabrier initial mass function, we find that power-law DOGs and bump DOGs are on average a factor of 2 and 1.5 more massive than SMGs, respectively (median and inter-quartile M{sub *} values for SMGs, bump DOGs, and power-law DOGs are log(M{sub *}/M{sub Sun }) = 10.42{sup +0.42}{sub -0.36}, 10.62{sup +0.36}{sub -0.32}, and 10.71{sup +0.40}{sub -0.34}, respectively). More realistic star formation histories drawn from two competing theories for the nature of ULIRGs at z {approx} 2 (major merger versus smooth accretion) can increase these mass estimates by up to 0.5 dex. A comparison of our stellar masses with the instantaneous star formation rate (SFR) in these z {approx} 2 ULIRGs provides a preliminary indication supporting high SFRs for a given M{sub *}, a situation that arises more naturally in major mergers than in smooth accretion-powered systems.

• OSTI ID: 22004204
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 744; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DUSTS
ENERGY SPECTRA
GALACTIC EVOLUTION
GALAXIES
GALAXY NUCLEI
PHOTOMETRY
PHOTON EMISSION
RED SHIFT
STARS
TELESCOPES
ULTRAVIOLET RADIATION