NuSTAR and XMM-Newton Observations of NGC 1365: Extreme Absorption Variability and a Constant Inner Disc
Abstract
Measurement of black hole spin in active galactic nuclei has the potential to enhance our understanding of how the black holes powering these sources grew to be so massive. To date, the best methods for measuring AGN spin are anchored in X-ray spectroscopy, and primarily involve studying relativistic reflection features from the inner accretion disc. However, there has been a long-standing debate surrounding such measurements, with models dominated by absorption and reprocessing in distant structures proposed as alternative interpretations of the observed X-ray spectra. We present the results from a series of four coordinated NuSTAR+XMM-Newton observations of the Seyfert galaxy NGC 1365, which has recently become central to this debate. Despite exhibiting an extreme range of absorption states, each of the observations displays the same characteristic signatures of relativistic reflection from the inner accretion disc. Through time-resolved spectroscopy, we find a clear link between the broad iron emission and the Compton reflection hump, and that each of the observations independently gives consistent parameters for the inner disc. These results strongly support the view that such regions are both observationally accessible and influence the observed spectra, and confirm that NGC 1365 hosts a rapidly rotating black hole.
- Publication:
-
The X-ray Universe 2014
- Pub Date:
- July 2014
- Bibcode:
- 2014xru..confE.203W