2009/05/27 by A. C. Fabian, A. Zoghbi, Fabian, A. C. +31
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.0905.4383
To appear in Nature May 28 2009, 12 pages with 11 figures
arxiv created 2009/05/27 · arxiv updated 2009/12/01
Since the discovery of the first broad iron-K line in 1995 from the Seyfert Galaxy MCG--6-30-15, broad iron-K lines have been found in several other Seyfert galaxies, from accreting stellar mass black holes and even from accreting neutron stars. The iron-K line is prominent in the reflection spectrum created by the hard X-ray continuum irradiating dense accreting matter. Relativistic distortion of the line makes it sensitive to the strong gravity and spin of the black hole. The accompanying iron-L line emission should be detectable when the iron abundance is high. Here we report the first discovery of both iron-K and L emission, using XMM-Newton observations of the Narrow-Line Seyfert 1 Galaxy 1H0707-495. The bright Fe-L emission has enabled us, for the first time, to detect a reverberation lag of 30 s between the direct X-ray continuum and its reflection from matter falling into the hole. The observed reverberation timescale is comparable to the light-crossing time of the innermost radii around a supermassive black hole. The combination of spectral and timing data on 1H0707-495 provides strong evidence that we are witnessing emission from matter within a gravitational radius, or a fraction of a light-minute, from the event horizon of a rapidly-spinning, massive black hole.