2011/01/31 by Christopher C. Hayward, Dušan Kereš, Patrik Jonsson +5 · 214 citations
Chemistry · Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Chemistry #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Luminosity #Physics #Population #Star formation #Stars #Submillimeter Array #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/743/2/159
published in The Astrophysical Journal 743(2), 159 (IOP Publishing) · 15 pages, 3 figures. Accepted for publication in ApJ. Minor changes from v1
arxiv created 2011/09/13 · openalex publication_date 2011/12/02 · arxiv updated 2012/08/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We perform three-dimensional dust radiative transfer (RT) calculations on hydrodynamic simulations of isolated and merging disk galaxies in order to quantitatively study the dependence of observed-frame submillimeter (submm) flux density on galaxy properties. We find that submm flux density and star formation rate (SFR) are related in dramatically different ways for quiescently star-forming galaxies and starbursts. Because the stars formed in the merger-induced starburst do not dominate the bolometric luminosity and the rapid drop in dust mass and more compact geometry cause a sharp increase in dust temperature during the burst, starbursts are very inefficient at boosting submm flux density (e.g., a ≳ 16 × boost in SFR yields a ≲ 2 × boost in submm flux density). Moreover, the ratio of submm flux density to SFR differs significantly between the two modes; thus one cannot assume that the galaxies with highest submm flux density are necessarily those with the highest bolometric luminosity or SFR. These results have important consequences for the bright submillimeter-selected galaxy (SMG) population. Among them are: (1) The SMG population is heterogeneous. In addition to merger-driven starbursts, there is a subpopulation of galaxy pairs, where two disks undergoing a major merger but not yet strongly interacting are blended into one submm source because of the large (≳ 15" or ∼130 kpc at z = 2) beam of single-dish submm telescopes. (2) SMGs must be very massive ( M ⋆ ≳ 6 × 10 10 M ☉ ). (3) The infall phase makes the SMG duty cycle a factor of a few greater than what is expected for a merger-driven starburst. Finally, we provide fitting functions for SCUBA and AzTEC submm flux densities as a function of SFR and dust mass and bolometric luminosity and dust mass; these should be useful for calculating submm flux density in semi-analytic models and cosmological simulations when performing full RT is computationally not feasible.