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arXiv · 1111.2869

The Star-Formation Histories of z~2 DOGs and SMGs

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

The Spitzer Space Telescope has identified a population of ultra-luminous infrared galaxies (ULIRGs) at z ~ 2 that may play an important role in the evolution of massive galaxies. We measure the stellar masses of two populations of Spitzer-selected ULIRGs, both of which have extremely red R-[24] colors (dust-obscured galaxies, or DOGs) and compare our results with sub-millimeter selected galaxies (SMGs). One set of 39 DOGs has a local maximum in their mid-IR spectral energy distribution (SED) at rest-frame 1.6um associated with stellar emission ("bump DOGs"), while the other set of 51 DOGs has a power-law dominated mid-IR SED with spectral features typical of obscured AGN ("power-law DOGs"). We use stellar population synthesis models applied self-consistently to broad-band photometry in the rest-frame ultra-violet, optical, and near-infrared of each of these populations and test a variety of stellar population synthesis codes, star-formation histories (SFHs), and initial mass functions (IMFs). Assuming a simple stellar population SFH and a Chabrier IMF, we find that the median and inner quartile stellar masses of SMGs, bump DOGs and power-law DOGs are given by log(M_*/M_sun) = 10.42_-0.36^+0.42, 10.62_-0.32^+0.36, and 10.71_-0.34^+0.40, respectively. Implementing more complicated SFHs with multiple age components increases these mass estimates by up to 0.5 dex. Our stellar mass estimates are consistent with physical mechanisms for the origin of z~2 ULIRGs that result in high star-formation rates for a given stellar mass. Such mechanisms are usually driven by a major merger of two gas-rich systems, rather than smooth accretion of gas and small satellites.

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R. S. Bussmann, Arjun Dey, L. Armus, M. J. I. Brown, V. Desai, A. H. Gonzalez, B. T. Jannuzi, J. Melbourne, B. T. Soifer. 2011-11-11. The Star-Formation Histories of z~2 DOGs and SMGs. https://doi.org/10.1088/0004-637x%2F744%2F2%2F150

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