题目：The Extremely Luminous Dust-Obscured Galaxies and Beyond
报告人：Chao-Wei Tsai 博士（University of California）
摘要：I present a class of distant dust-enshrouded galaxies with extremely high luminosity, including several "Extremely Luminous Infrared Galaxies" (ELIRGs) that reach 10^14 L_Sun. Selected by their extreme red colors in WISE bands, their SEDs incorporating WISE, Spitzer, and Herschel photometry indicate hot dust dominates the bolometric luminosity. These sources are likely powered by highly obscured active galactic nuclei (AGN), are unlikely to be lensed. The existence of ELIRGs at z > 3 constrains the supermassive black hole (SMBH) growth history, suggesting that these SMBH's are born with large mass, or have a very rapid mass assembly, presumably by chaotic accretion. Their low source density (~ 10^-5 of LIRGs' at similar redshift) implies that these objects are intrinsically rare, or are a short-lived phase in a more numerous population. These sources have absorption-corrected X-ray luminosity significantly fainter than the mid-IR/X-ray correlation for AGNs, suggesting that they might be intrinsically X-ray weak. The ALMA C+ observation on selected sample shows a large, homogeneous velocity dispersion across few kpc, suggesting that gas is being blown away isotropically, possibility reflecting the stage of becoming unsecured quasars.
In the process of finding these luminous dust-enshrouded galaxies with WISE, we have also accidentally discovered some unusual galaxies due to their unexpected mid-IR colors. For example, we have identified a double-peaked broad line AGN with wiggled radio jets which might indicate certain dynamical interactions at the center of the system. In addition, we have discovered a few dozen of mid-IR-bright dwarf galaxies. Inspired by these discoveries, a few followup investigations are initiated to study the dust and gas properties in the AGN and starburst dwarf galaxies in mid-IR and far-IR with Subaru and SOFIA telescopes, and at radio wavelengths with Arecibo telescope and FAST. I will discuss their applications to the upcoming and future astronomical facilities beyond 2020.