Events in Physics
Wednesday, October 17, 2012
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Rubens Reis (University of Michigan)PS.017aAstronomy Seminar Rubens Reis Title: Putting a spin on black holes Abstract: An astrophysical black hole is fully defined by just two parameters: its mass and spin. With the advent of modern X-ray satellites such as XMM-Newton and Chandra came a leap in our understanding of the fundamental physics of these powerful objects. We are now at a stage where information on the mass and spin of black holes is available for over a dozen X-ray binaries, and we are in the process of obtaining the spin for a similar number of supermassive black holes. X-ray observations of stellar-mass black holes provide three independent means from which we can estimate the black hole spin: i) thermal emission emanating from the accretion disk; ii) relativistic distortion to emission lines; and iii) quasi-periodic variations in the light originating in the system. In this talk, I will summarise the current status of the field after reviewing and discussing the validity and physical assumptions of these methods. Furthermore, I will present evidence that both the spectral and timing properties of black hole states may be partially driven by the height of the X-ray emitting corona above the accretion disk, and related changes in how General Relativity (light-bending) affects the corona–disk interaction. |