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Seminars

Super-critical accretion onto compact objects: radiation and outflows

by Dr Roberto Soria (the University of the Chinese Academy of Sciences)

Asia/Shanghai
ONLINE

ONLINE

Description
Abstract

Until a few years ago, the physics of accretion onto compact objects was usually investigated for the regime below the critical Eddington rate. However, the super-critical accretion regime has now become a very active area of research. In the distant universe, super-critical accretion in quasars may have led to the rapid growth of nuclear black holes from intermediate-mass to supermassive: so, quantifying the photon and outflow output in such regime is crucial for our understanding of feedback and galaxy evolution. In the local universe, super-critical accretion happens today in a sub-population of X-ray binaries (ultraluminous X-ray sources), including those that will become progenitors of gravitational merger events. The inflow/outflow structure and geometry of emission of such super-critical sources is still hotly debated, with various attempts to progress from a phenomenological classification of sub-types towards a "unification scheme" similar to the one successfully applied to AGN in the 1990s. I will focus in particular on the role of jets and outflows in the super-critical regime: how we can detect them and how we can measure their power. I will illustrate recently discovered examples in nearby galaxies of super-critical compact objects surrounded by shock-ionized bubbles, evidence of their powerful outflows.

Biography

I received my PhD from the Australian National University. I was then Marie Curie International Fellow at the Harvard-Smithsonian Center for Astrophysics, and Leverhulme Trust Early-Career Fellow at University College London. I went back to Australia as a Senior Research Fellow at ICRAR-Curtin University (Perth). I am now a professor at the University of the Chinese Academy of Sciences (NAOC) in Beijing, and an Honorary Associate at the University of Sydney.

Chair
Professor Dong Lai
Division
Astronomy and Astrophysics
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