BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Physics-TWaP
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2953
DTSTART:20130131T153000
DTEND:20130131T170000
LOCATION:4421 Sterling Hall
SUMMARY:Unambigious tests of general relativity with Xray Spectroscopy of AGN\, Astronomy Colloquium\, Guido Risaliti\, Harvard Smithsonian Cfa/Observatory of Florence
DESCRIPTION:<br><br>
<br><br>
Active Galactic Nuclei (AGN) are optimal laboratories for tests of general relativity (GR) in the &quot;strong field&quot; regime. In particular their X-ray emission comes from a few gravitational radii from the horizon event of the supermassive black hole\, and is strongly affected by GR effects. However\,  testing GR has been difficult so far because of a strong degeneracy in the X-ray spectra of AGN between the (relativistically distorted) intrinsic emission and the complex absorption/reflection components due to the circumnuclear medium. I will review the main diagnostic methods developed in the past few years to investigate this issue\, focusing on time-resolved spectral analysis of variable sources\, and I will discuss the impact in this field of the recently launched hard X-ray telescope NuSTAR. I will show how the availability of high quality broad-band X-ray spectra\, and a time-resolved spectral analysis can remove the main systematic uncertainties in GR tests\, provide precise measurements of black hole spins\, and reveal the structure of the circumnuclear X-ray absorber.
URL:http://www.physics.wisc.edu/twap/view.php?id=2953
END:VEVENT
END:VCALENDAR