An Evolutionary Model for Submillimeter Galaxies

Abstract

We calculate multiwavelength spectral energy distributions (SEDs) from simulations of major galaxy mergers with black hole feedback that produce submillimeter bright galaxies (SMGs), using the self-consistent three-dimensional radiative transfer code RADISHE. These calculations allow us to predict multiwavelength correlations for this important class of galaxies. We review star formation rates, the time evolution of the 850 μm fluxes, along with the time evolution of the MBH − M⋆ relation of the SMGs formed in the mergers. We reproduce correlations for local AGNs observed in Spitzer Space Telescope's IRAC bands, and make definitive predictions for infrared X-ray correlations. Our dynamical approach allows us to directly correlate observed clustering in the data as seen in IRAC color-color plots with the relative amount of time the system spends in a region of color-color space. We also find that this clustering is positively correlated with the stars dominating in their contribution to the total bolometric luminosity. We compare our calculated SEDs to observations of SMGs and find good agreement. We introduce a simple, heuristic classification scheme which we present in terms of the LIR/LX ratios of these galaxies, which may be interpreted as an evolutionary scheme, as these galaxies evolve in LIR/LX while transiting from a X-ray underluminous infrared bright phase (class I, LIR/LX≳ 100), through a quasar phase (class II, LIR/LX ∼ 25), to a merger remnant (class III, LIR/LX≲ 10). We find that SMGs are a broader class of systems than starbursts or quasars, traversing the range from class I to class II systems.