Cygx1 spectrum

This is the X-ray energy spectrum of Cygnus X-1, a candidate black hole. The data is from the Chandra space telescope. The original caption read as follows:

These data profile the X-ray spectral line from iron atoms in the accretion disk around the black hole. Note how the profile is skewed toward energies lower than the expected peak at 6.4 keV. The Chandra data on Cygnus X-1 show evidence of strong gravitational effects, with some atoms as close as 100 miles from the black hole, but no evidence of spin. Chandra X-ray Observatory ACIS/HETGS spectrum.