MIfA Colloquium: Jay Gallagher (UW Madison)

Title: Dark Powers: The Emerging Astrophysics of Extraordinarily Luminous Compact Obscured Nuclei in the Local Universe

Abstract: Obscuration is a well-established feature of luminous galaxy nuclei. While the majority of AGN and starburst nuclei suffer significant dust obscuration, in most cases the obscuration is not complete and some direct radiation from the central source escapes. Recent studies with mm/submm interferometers have revealed the most extreme class of obscured nuclei. These compact (R< 10s of pc) obscured nuclei (CONs) appear to be completely hidden from the x-rays to the submm by high optical depth dusty interstellar matter. Due to the presence of their massive low angular momentum gas cloaks, CONs are relatively massive. They are systematically luminous, thus far only are found in LIRGs and ULIRGs. CONs therefore have inconsistent properties in combining high luminosities with a dusty, dense interstellar medium that will be subject to radiation pressure and other intense feedback processes. In this talk I will review the astrophysics of CONs and their possible role in the evolution of galaxy nuclei. The discussion will focus on the key issues of CON power sources, development of massive, compact central gas concentrations, and evolution, areas that are under active study, particularly by the CON-quest collaboration.