| A Physical Model for z~2 Dust Obscured Galaxies (2009) | |||||||||
Abstract | |||||||||
| We present a physical model for the origin of z~2 Dust-Obscured Galaxies (DOGs), a class of high-redshift ULIRGs selected at 24 micron which are particularly optically faint (F24/FR>1000). By combining N-body/SPH simulations of high redshift galaxy evolution with 3D polychromatic dust radiative transfer models, we find that luminous DOGs (with F24 > 0.3 mJy at z~2) are well-modeled as extreme gas-rich mergers in massive (~5x10^12-10^13 Msun) halos, with elevated star formation rates (~500-1000 Msun/yr) and/or significant AGN growth (Mdot(BH) > 0.5 Msun/yr), whereas less luminous DOGs are more diverse in nature. Merger-driven DOGs are caught in a stage transitioning from being starburst dominated to AGN dominated, evolving from a "bump" to a power-law shaped mid-IR (IRAC) spectral energy distribution (SED). While canonically power-law galaxies are associated with being AGN-dominated, we find that the power-law mid-IR SED can owe both to direct AGN contribution, as well as to a heavily dust obscured stellar bump at times that the galaxy is starburst dominated. Thus power-law galaxies can be either starburst or AGN dominated. Less luminous DOGs (100 < F24 < 300 microJy at z=2) can be well-represented either by mergers, or by less extreme secularly evolving gas-rich disk galaxies (with SFR > 50 Msun/yr). We find that some merger-driven DOGs can be selected as Submillimeter Galaxies (SMGs), while both merger-driven and secularly evolving DOGs typically satisfy the BzK selection criteria. Our models provide testable predictions of the physical masses, dust temperatures, CO line widths and location on the M*-MBH relation of DOGs. Finally, we provide public SED templates derived from these simulations.. Comment: Submitted to MNRAS. Full Resolution Version available at http://www.cfa.harvard.edu/~dnarayan/dogpaper.pdf replacement: minor changes to 2 figures | |||||||||
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