Pair-Rich Corona of an Accreting Kerr Black Hole

Fuente: arXiv
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Main Authors: Zhang, Jonathan, Thompson, Christopher
Format: Preprint
Published: 2026
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author Zhang, Jonathan
Thompson, Christopher
author_facet Zhang, Jonathan
Thompson, Christopher
contents We build a self-consistent model of a warm scattering corona near an accreting black hole in Kerr geometry, in the regime of slow ($\sim 0.01$ Eddington) mass accretion. An iterative Monte Carlo procedure is developed that incorporates self-consistently the effects of Compton scattering and electron-positron pair creation, as well as general relativistic lensing and frame dragging effects. Soft thermal photons are seeded in the inner disk and the velocity dispersion of the electrons and positrons adjusted to yield a fixed seed luminosity amplification through Compton scattering. A simple kinematic prescription is also added for bulk outflow. Pair creation by photon collisions raises significantly the density of scattering charges in and around the innermost ion disk, which is assumed to be geometrically thick and rarefied compared with the disk outside 10 gravitational radii. The self-consistent pair cloud is concentrated closer to the BH. The spectrum and polarization of the escaping X-rays are recorded as a function of the observer's orientation. The temperature and Compton parameter measured from the output spectra using the compPS package are consistent with fits to binary BH data in the hardest spectral state; the polarization degree rises to $4-10\%$ through the 2-8 keV band with allowance for $e^\pm$ upflow from the BH equator.
format Preprint
id arxiv_https___arxiv_org_abs_2604_24961
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Pair-Rich Corona of an Accreting Kerr Black Hole
Zhang, Jonathan
Thompson, Christopher
High Energy Astrophysical Phenomena
We build a self-consistent model of a warm scattering corona near an accreting black hole in Kerr geometry, in the regime of slow ($\sim 0.01$ Eddington) mass accretion. An iterative Monte Carlo procedure is developed that incorporates self-consistently the effects of Compton scattering and electron-positron pair creation, as well as general relativistic lensing and frame dragging effects. Soft thermal photons are seeded in the inner disk and the velocity dispersion of the electrons and positrons adjusted to yield a fixed seed luminosity amplification through Compton scattering. A simple kinematic prescription is also added for bulk outflow. Pair creation by photon collisions raises significantly the density of scattering charges in and around the innermost ion disk, which is assumed to be geometrically thick and rarefied compared with the disk outside 10 gravitational radii. The self-consistent pair cloud is concentrated closer to the BH. The spectrum and polarization of the escaping X-rays are recorded as a function of the observer's orientation. The temperature and Compton parameter measured from the output spectra using the compPS package are consistent with fits to binary BH data in the hardest spectral state; the polarization degree rises to $4-10\%$ through the 2-8 keV band with allowance for $e^\pm$ upflow from the BH equator.
title Pair-Rich Corona of an Accreting Kerr Black Hole
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2604.24961