Role of emission angular directionality in spin determination of accreting black holes with broad iron line

Understand

Spin of an accreting black hole can be determined by spectroscopy of the emission and absorption features produced in the inner regions of an accretion disc.

• We discuss the method employing the relativistic line profiles of iron in the X-ray domain, where the emergent spectrum is blurred by general relativistic effects.
• Precision of spectra fitting procedure could be compromised by inappropriate account of the angular distribution of the disc emission.
• Often a unique profile is assumed, invariable over the entire range of radii in the disc and energy in the spectral band.