The Star Formation Histories of z ~ 2 Dust-obscured Galaxies and Submillimeter-selected Galaxies

January 2012 • 2012ApJ...744..150B

Authors • Bussmann, R. S. • Dey, Arjun • Armus, L. • Brown, M. J. I. • Desai, V. • Gonzalez, A. H. • Jannuzi, B. T. • Melbourne, J. • Soifer, B. T.

Abstract • The Spitzer Space Telescope has identified a population of ultraluminous infrared galaxies (ULIRGs) at z ~ 2 that may play an important role in the evolution of massive galaxies. We measure the stellar masses (M _*) 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 μm associated with stellar emission ("bump DOGs"), while the other set of 51 DOGs have power-law mid-IR SEDs that are typical of obscured active galactic nuclei ("power-law DOGs"). We measure M _* by applying Charlot & 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 _* values for SMGs, bump DOGs, and power-law DOGs are log(M _*/M _⊙) = 10.42^+0.42 _{- 0.36}, 10.62^+0.36 _{- 0.32}, and 10.71^+0.40 _{- 0.34}, respectively). More realistic star formation histories drawn from two competing theories for the nature of ULIRGs at z ~ 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 ~ 2 ULIRGs provides a preliminary indication supporting high SFRs for a given M _*, a situation that arises more naturally in major mergers than in smooth accretion-powered systems.

Links

• PREPRINT http://arxiv.org/abs/1111.2869
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2012ApJ...744..150B
• ELECTR https://doi.org/10.1088%2F0004-637X%2F744%2F2%2F150
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2012ApJ...744..150B
• PDF https://stacks.iop.org/0004-637X/744/150/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/744/150
• DATA https://archive.gemini.edu/searchform/publication=2012ApJ...744..150B
• DATA https://irsa.ipac.caltech.edu/bibdata/2012/B/2012ApJ...744..150B.html