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Colloquium Speaker: Dom Walton (University of Cambridge)
March 17, 2021 @ 3:30 pm - 5:00 pm
Speaker: Dom Walton (University of Cambridge)
Title: Putting a Spin on Black Holes in the NuSTAR Era
Abstract: Black holes (BHs) are fully defined by only two quantities: mass and spin. Measurements of BH spin have a wide variety of astrophysical applications, from learning about the growth history of supermassive black holes (SMBHs) to understanding relativistic jets, and so are of particular importance. The most broadly applicable method available for constraining BH spin is anchored in X-ray spectroscopy, and involves the study of the relativistic reflection from the innermost accretion disc in actively accreting systems, either active galactic nuclei (AGN) or X-ray binaries (XRBs). This is an area in which the broadband coverage provided by NuSTAR has played a critical role, covering both the relativistically broadened iron line and the associated high-energy continuum to provide an unprecedented view of these key reflection features. The quality of the data not only allows us
to make robust spin constraints, but also challenge the physical assumptions inherent in the relativistic reflection models primarily utilized for these measurements. I will discuss the current state of black hole spin measurements in the NuSTAR era, focusing in particular on the AGN population.