Recent X-ray observations have shown broad , skewed iron line emission from Seyfert 1 galaxies which is explained by the emission being fluorescence on a disk close to a black hole .
During one interval , the line in MCG–6-30-15 was so broad and redshifted that a Kerr black hole is implied .
We are therefore studying the effects of the Kerr metric on the line profile , and extending the work by Laor and Kojima which dealt only with extreme values of the spin parameter .
Here we report that the spin parameter of the black hole in MCG–6-30-15 is high ( a / M > 0.94 ) , and invert the line profile to obtain the disk emissivity profile , which approximates a power-law .
Continuum radiation returning to the disk because of the Kerr metric does not enhance the equivalent width of the line seen above 3 keV by more than about 20 per cent if the continuum source corotates with the disk .