BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2953
DTSTART:20130131T213000Z
DTEND:20130131T230000Z
DTSTAMP:20260420T004923Z
LAST-MODIFIED:20130129T202458Z
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>
\n<br><br>
\nActive Galactic Nuclei (AGN) are opt
 imal laboratories for tests of general relativity (GR) in the &quot\;s
 trong field&quot\; regime. In particular their X-ray emission comes fr
 om a few gravitational radii from the horizon event of the supermassiv
 e black hole\, and is strongly affected by GR effects. However\,  test
 ing GR has been difficult so far because of a strong degeneracy in the
  X-ray spectra of AGN between the (relativistically distorted) intrins
 ic emission and the complex absorption/reflection components due to th
 e circumnuclear medium. I will review the main diagnostic methods deve
 loped in the past few years to investigate this issue\, focusing on ti
 me-resolved spectral analysis of variable sources\, and I will discuss
  the impact in this field of the recently launched hard X-ray telescop
 e NuSTAR. I will show how the availability of high quality broad-band 
 X-ray spectra\, and a time-resolved spectral analysis can remove the m
 ain systematic uncertainties in GR tests\, provide precise measurement
 s of black hole spins\, and reveal the structure of the circumnuclear 
 X-ray absorber.
URL:https://www.physics.wisc.edu/events/?id=2953
END:VEVENT
END:VCALENDAR