Constraining the Spin of the Black Hole in Fairall 9 with Suzaku

TL;DR

This study uses Suzaku X-ray data to analyze the spectrum of Fairall 9, revealing a broad iron line and estimating the black hole's spin parameter as approximately 0.60, contributing to understanding black hole spin distribution.

Contribution

First measurement of the black hole spin in Fairall 9 using relativistic disk reflection modeling with Suzaku data.

Findings

Black hole spin parameter estimated at a=0.60(7)

Broad iron line detected and modeled as asymmetric

Inner disk extends to the innermost stable orbit

Abstract

We report on the results of spectral fits made to data obtained from a 168 ksec Suzaku observation of the Seyfert-1 galaxy Fairall 9. The source is clearly detected out to 30 keV. The observed spectrum is fairly simple; it is well-described by a power-law with a soft excess and disk reflection. A broad iron line is detected, and easily separated from distinct narrow components owing to the resolution of the CCDs in the X-ray Imaging Spectrometer (XIS). The broad line is revealed to be asymmetric, consistent with a disk origin. We fit the XIS and Hard X-ray Detector (HXD) spectra with relativistically-blurred disk reflection models. With the assumption that the inner disk extends to the innermost stable circular orbit, the best-fit model implies a black hole spin parameter of a = 0.60(7) and excludes extremal values at a high level of confidence. We discuss this result in the context of Seyfert observations and models of the cosmic distribution of black hole spin.