Magnetized disk models lower the thermal-viscous instability threshold to Eddington ratios of 0.01-0.03 and yield limit-cycle timescales of months to years, jointly matching observations in five CLAGN only when the inner disk is strongly magnetized.
Properties of AGN coronae in the NuSTAR era
5 Pith papers cite this work. Polarity classification is still indexing.
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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.
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astro-ph.HE 5years
2026 5roles
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Recursive formalism computes scattering-order-resolved photon escape probabilities in slab Thomson media, yielding exact mean scattering numbers like ⟨N⟩=2τ and eigenmode limits for high orders, verified by Monte Carlo.
The cosmologically integrated neutrino emission from supermassive black hole coronae in Seyfert galaxies can account for the sub-PeV diffuse extragalactic neutrino flux observed by IceCube.
Disk reflection from a compact lamp-post corona explains the X-ray polarization and spectra of NGC 4151.
Variable column density and covering factor of three ionized absorbers in clumpy disk winds explain the X-ray variability in I Zw 1 with stable corona.
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Photon Escape from Slab Thomson Media: A Scattering-order-resolved Recursive Formalism for Comptonization Applications
Recursive formalism computes scattering-order-resolved photon escape probabilities in slab Thomson media, yielding exact mean scattering numbers like ⟨N⟩=2τ and eigenmode limits for high orders, verified by Monte Carlo.