Constraints on the black hole spin in the quasar SDSS J094533.99+100950.1

TL;DR

This study estimates the black hole spin in quasar SDSS J094533.99+100950.1 using disk fitting methods, finding a moderate spin of around 0.3 and constraining it to be below 0.8, with implications for accretion physics.

Contribution

The paper develops a numerical code incorporating general relativity effects for disk modeling and applies it to estimate black hole spin from broad band spectra.

Findings

Black hole spin estimated at 0.3 with a lower limit of 0.8.

Disk extends down to the marginally stable orbit without additional components.

Accretion rate determined to be 0.13, below Eddington limit.

Abstract

The spin of the black hole is an important parameter which may be responsible for the properties of the inflow and outflow of the material surrounding a black hole. Broad band IR/optical/UV spectrum of the quasar SDSS J094533.99+100950.1 is clearly disk-dominated, with the spectrum peaking up in the observed frequency range. Therefore, disk fitting method usually used for Galactic black holes can be used in this object to determine the black hole spin. We develop the numerical code for computing disk properties, including radius-dependent hardening factor, and we apply the ray-tracing method to incorporate all general relativity effects in light propagation. We show that the simple multicolor disk model gives a good fit, without any other component required, and the disk extends down to the marginally stable orbit. The best fit accretion rate is 0.13, well below the Eddington limit, and the black hole spin is moderate, 0.3. The contour error for the fit combined with the constraints for the black hole mass and the disk inclination gives a constraint that the spin is lower than 0.8. We discuss the sources of possible systematic errors in the parameter determinations.