The Formation of High Redshift Submillimeter Galaxies

TL;DR

This paper presents a model combining hydrodynamic simulations and radiative transfer to explain the formation of high-redshift submillimeter galaxies, matching their observed properties and luminosities.

Contribution

It introduces a detailed physical model that reproduces the observed spectral energy distributions and luminosities of SMGs using galaxy merger simulations.

Findings

High-mass mergers produce the most luminous SMGs.

Galaxy mass and birthcloud covering fraction are key to 850 micron flux.

Models can reproduce both luminous and average SMGs.

Abstract

We describe a model for the formation of \zsim 2 Submillimeter Galaxies (SMGs) which simultaneously accounts for both average and bright SMGs while providing a reasonable match to their mean observed spectral energy distributions (SEDs). By coupling hydrodynamic simulations of galaxy mergers with the high resolution 3D polychromatic radiative transfer code Sunrise, we find that a mass sequence of merger models which use observational constraints as physical input naturally yield objects which exhibit black hole, bulge, and H2 gas masses similar to those observed in SMGs. The dominant drivers behind the 850 micron flux are the masses of the merging galaxies and the stellar birthcloud covering fraction. The most luminous (S850 ~ 15 mJy) sources are recovered by ~10^13 Msun 1:1 major mergers with a birthcloud covering fraction close to unity, whereas more average SMGs ~5-7 mJy) may be formed in lower mass halos ~5x10^12 Msun. These models demonstrate the need for high spatial resolution hydrodynamic and radiative transfer simulations in matching both the most luminous sources as well as the full SEDs of SMGs. While these models suggest a natural formation mechanism for SMGs, they do not attempt to match cosmological statistics of galaxy populations; future efforts along this line will help ascertain the robustness of these models.