Credit: J. M. Miller et al., 2002, ApJ, 577, L15
Near a Nearby Black Hole
Astronomers want to get as close as possible to a black hole - from a safe distance of course. Their interest is due to the fact that black holes possess extremely strong gravitational fields, impossible to reproduce on earth; so by looking near black holes, astronomers can determine how matter affects space and time. One way to probe the inner space near black holes is to look at the
effects of the black hole's gravity on X-ray emission lines formed near the black hole, in the accretion disk of material swirling into the black holes event horizon. An observation by the BeppoSAX observatory of the X-ray spectrum of a suspected black hole in the Milky Way called V4641 Sgr shows a contorted emission line produced by hot Fe atoms near the event horizon. The image of the spectrum above shows the data as crosses along with a red line representing the best model fit to the data. The iron line is the double-peaked feature represented by the dot-dashed line stretching from about 4.5 to 7 keV (the spectrum also shows 2 other emission components produced by hot electrons in the accretion disk as dotted and dashed lines produced). By studying emission lines from these systems astronomers hope to disentangle effects produced by gravitational space-bending from instabilities in the accretion disk itself to unravel the mystery of gravity, space and time.
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Page Author: Dr. Michael F. Corcoran
Last modified September 1, 2002
