2001/02/02 by Grzegorz Wardzinski, G. Wardziński, A. A. Zdziarski +1 · 5 citations
Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Compton scattering #Electron #Electron temperature #Equipartition theorem #Galaxy #Luminosity #Magnetic field #Nuclear physics #Optics #Photon #Physics #Plasma #Pulsars and Gravitational Waves Research #Spectral line #Synchrotron #Thermal #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2001.04387.x
published as Mon.Not.Roy.Astron.Soc. 325 (2001) 963 · 10 pages, 9 postscript figures. Accepted to MNRAS
arxiv created 2001/02/02 · openalex publication_date 2001/08/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate how the presence of a non-thermal tail beyond a Maxwellian electron distribution affects the synchrotron process as well as Comptonization in plasmas with parameters typical for accretion flows on to black holes. We find that the presence of the tail can significantly increase the net (after accounting for self-absorption) cyclo-synchrotron emission of the plasma, which then provides seed photons for Compton upscattering. Thus, the luminosity in the thermally Comptonized spectrum is enhanced as well. The importance of these effects increases with both increasing Eddington ratio and black hole mass. The enhancement of the Comptonized synchrotron luminosity can be as large as ∼103 and ∼105 for stellar and supermassive black holes, respectively, when the energy content in the non-thermal tail is 1 per cent. The presence of the tail only weakly hardens the thermal Comptonization spectrum but it leads to the formation of a high-energy tail beyond the thermal cut-off, which two effects are independent of the nature of the seed photons. Since observations of high-energy tails in Comptonization spectra can constrain the non-thermal tails in the electron distribution and thus the Comptonized synchrotron luminosity, they provide upper limits on the strength of magnetic fields in accretion flows. In particular, the measurement of an MeV tail in the hard state of Cyg X-1 by McConnell et al. implies the magnetic field strength in this source to be at most an order of magnitude below equipartition.