We present an analysis of the observed broad iron line feature and putative warm absorber in the long 2001 XMM-Newton observation of the Seyfert-1.2 galaxy MCG–6-30-15 .
The new kerrdisk model we have designed for simulating line emission from accretion disk systems allows black hole spin to be a free parameter in the fit , enabling the user to formally constrain the angular momentum of a black hole , among other physical parameters of the system .
In an important extension of previous work , we derive constraints on the black hole spin in MCG–6-30-15 using a self-consistent model for X-ray reflection from the surface of the accretion disk while simultaneously accounting for absorption by dusty photoionized material along the line of sight ( the warm absorber ) .
Even including these complications , the XMM-Newton /EPIC-pn data require extreme relativistic broadening of the X-ray reflection spectrum ; assuming no emission from within the radius of marginal stability , we derive a formal constraint on the dimensionless black hole spin parameter of a = 0.989 ^ { +0.009 } _ { -0.002 } at 90 \% confidence .
The principal unmodeled effect that can significantly reduce the inferred black hole spin is powerful emission from within the radius of marginal stability .
Although significant theoretical developments are required to fully understand this region , we argue that the need for a rapidly spinning black hole is robust to physically plausible levels of emission from within the radius of marginal stability .
In particular , we show that a non-rotating black hole is strongly ruled out .