Coronal properties from NuSTAR observations of AGN and their implications
Abstract
A significant fraction of the power produced by accretion onto the central black hole of AGN is released in the X-ray band. It is widely accepted that this emission is produced by inverse Compton scattering of UV disc photons by a region of electron plasma known as the corona.However, the detailed conditions in the corona are still poorly constrained.The recent NuSTAR mission, with significantly greater sensitivity in the hard X-ray band than previous missions, has allowed a step-change in the quality of our observations of the corona.In particular, the Comptonised continuum can now be measured for many sources up to around its high energy cut-off, allowing precise measurements of the coronal temperature and other related parameters.These measurements suggest that pair production may play an important role in the regulation of coronal temperatures.The increasing sample of sources with high-quality NuSTAR observations allows us to improve the detail and precision of our inferences, such as by considering the prevalence of non-thermal electrons in the plasma.We will present the latest results from our ongoing campaigns to measure coronal properties with NuSTAR and the significance of these results for the wider accretion process.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E.462B