Properties of AGN coronae in the NuSTAR era
arXiv:1505.07603
Abstract
The focussing optics of NuSTAR have enabled high signal-to-noise spectra to be obtained from many X-ray bright Active Galactic Nuclei (AGN) and Galactic Black Hole Binaries (BHB). Spectral modelling then allows robust characterization of the spectral index and upper energy cutoff of the coronal power-law continuum, after accounting for reflection and absorption effects. Spectral-timing studies, such as reverberation and broad iron line fitting, of these sources yield coronal sizes, often showing them to be small and in the range of 3 to 10 gravitational radii in size. Our results indicate that coronae are hot and radiatively compact, lying close to the boundary of the region in the compactness - temperature diagram which is forbidden due to runaway pair production. The coincidence suggests that pair production and annihilation are essential ingredients in the coronae of AGN and BHB and that they control the shape of the observed spectra.
arXiv comment11 pages, 8 figures, accepted for publication in MNRAS
Cited by in corpus (7)
- Positron annihilation signatures associated with the outburst of the microquasar V404 Cygni
- The rhythm of Fairall 9 -- I: Observing the spectral variability with XMM-Newton and NuSTAR
- The high energy universe at ultra-high resolution: the power and promise of X-ray interferometry
- Lagrangian formulation of the general relativistic Poynting-Robertson effect
- The content of astrophysical jets
- Accreting Black Holes
- The 511-CAM Mission: A Pointed 511 keV Gamma-Ray Telescope with a Focal Plane Detector Made of Stacked Transition Edge Sensor Microcalorimeter Arrays