The Surprising Diversity of Dust-Selected Galaxies in the Local Submillimetre Universe
Dust, Gas and Star Formation in Galaxies Throughout Cosmic Time
Christopher Clark
Cardiff University
Loretta Dunne (University of Canterbury), Haley Gomez (Cardiff University)
We present the first 250µm blind sample of nearby galaxies (15 cal Terahertz Large Area Survey (H-ATLAS). Herschel’s sensitivity us probe the faint end of the dust luminosity function for the first time, spanning a range of stellar mass (ranging from 7.4 to 11.3 log10 Msol), star formation activity (SSFRs ranging from -11.8 to -8.9 log10 yr -1), and gas fraction (ranging from 3 to 96 %). The median cold dust temperature is 14.6 K, colder than in the HRS (18.5 K) and Planck (17.7 K). The mean dust-to-stellar mass ratio in our sample is higher than in these surveys by factors of 3.7 and 1.8 respectively. Counter-intuitively, we find that the more dust rich a galaxy, the lower its UV attenuation. Over half of our dust selected galaxies are extremely blue in UV-NIR colour, with irregular and/or highly flocculent morphology. These very blue galaxies account for only 6% of the stellar mass in our sample, but contain over 35% of the dust mass, and 50% of the HI mass. These are the most actively star forming galaxies in our sample, with the highest gas fractions and lowest UV attenuations. These galaxies appear to be immature, still in an early stage of converting their gas into stars; they should therefore provide valuable insights into the chemical evolution of young, gas- and dust-rich galaxies.
09:00 - 10:30