Characteristics of an Extreme Dusty Star-forming Galaxy at z = 4.5

Abstract

We present new physical properties for an extreme (L IR > 1013 L ⊙), unlensed dusty star-forming galaxy at z = 4.531, G09-81106. We compile fluxes from the literature, and include new Hubble Space Telescope data to generate SED models under various assumptions. G09-81106 has a number of physical characteristics that far surpass the average data for DSFGs, including high dust temperature (∼70 K) and star formation rate ( > 2 × 103 M ⊙ yr−1). While barely within the average star-forming main sequence region, G09 is already an order of magnitude more massive and more star-forming than most star-forming galaxies at similar epochs. Visual inspection suggests these exceptional properties may be due to an ongoing merger, though future work with spatially resolved imaging and spectroscopic analysis will reveal its true nature.