RSAA Colloquia / Seminars / Feast-of-Facts: Friday, 21 April 2017, 14:30-14:50; Duffield Lecture Theatre

Jason Chu

"Understanding Local Luminous Infrared Galaxies in the Herschel Era"

Luminous and ultraluminous infrared galaxies [(U)LIRGs] are some of the most extreme objects in the universe with their elevated star formation rates and/or presence of a powerful AGN, playing a central role in the evolution of galaxies throughout cosmic history. The 201 local (U)LIRGs (z<0.088) comprising the Great Observatories All-Sky LIRG Survey (GOALS) provide an unmatched opportunity to characterize their diverse properties in a large, statistically significant sample, in addition to comparisons with their high redshift counterparts. In this talk I will first present the Herschel PACS and SPIRE far infrared image atlas of the entire GOALS sample (encompassing the 70-500 micron wavelength range), and demonstrate the excellent data quality as described in Chu et al. (2017). The Herschel GOALS images presented here are the highest resolution, most sensitive and comprehensive far-infrared imaging survey of the nearest (U)LIRGs to date. This allows us for the first time to directly probe the critical far infrared and submillimeter wavelength regime of these systems, enabling us to accurately determine their bolometric luminosities, infrared surface brightnesses, star formation rates, and dust masses and temperatures on spatial scales of 2-5 kpc. In addition, the superb resolution of Herschel means we can resolve many of the galaxy pairs and systems within the GOALS sample, allowing us to measure far infrared fluxes of component galaxies. Finally, using the Herschel photometry in conjunction with Spitzer, WISE, and IRAS data, I will show our first results on the global properties of (U)LIRGs such as their average 3-500 micron infrared SEDs and far infrared colors, and compare them to lower infrared luminosity objects. We also compare and contrast their infrared SED shapes with previously published SED templates from the literature which will be presented in an upcoming paper. Finally as a treat, I will show some of my favorite photographs and a time lapse video from Maunakea, one of the best astronomical observing sites in Hawai`i.