Synthesis of accretion disk and nonthermal source models for active galactic nuclei

Abstract

view Abstract Citations (30) References (49) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Synthesis of Accretion Disk and Nonthermal Source Models for Active Galactic Nuclei Band, David L. ; Malkan, Matthew A. Abstract We fitted multiwavelength observations of 12 active galactic nuclei (AGNs) with a model consisting of a nonthermal source surrounding an accretion disk around a massive black hole. The accretion disk radiates the optical and ultraviolet continua. The nonthermal source produces the infrared and soft X-ray continua by synchrotron emission, and the hard X-ray spectrum by inverse Compton scattering of photons from the accretion disk. By fitting the multiwavelength spectrum of a given AGN, we derive the black hole mass and accretion rate, and the nonthermal source size, magnetic field, and relativistic electron distribution. We find that the typical AGN radiates at nearly the Eddington luminosity and that the radius of the nonthermal source is of order 30-100 Schwarzschild radii. The photon energy density is comparable to the magnetic field energy density, while the relativistic electron energy density is much smaller. The electron lifetime due to radiative losses is very short, and electrons must be (re)accelerated throughout the source. We show that relativistic electrons are probably not produced as secondaries in proton-proton collisions because this would require large scattering optical depths and high relativistic proton energy densities. The gamma-ray compactness indicates that the source becomes optically thick to photon-photon pair production, but a pair cascade will not be produced. The small black-hole masses are more consistent with some density evolution rather than pure luminosity evolution of the AGN luminosity function. Publication: The Astrophysical Journal Pub Date: October 1989 DOI: 10.1086/167886 Bibcode: 1989ApJ...345..122B Keywords: Accretion Disks; Active Galactic Nuclei; Black Holes (Astronomy); Nonthermal Radiation; Spectrophotometry; Electron Energy; Luminosity; Pair Production; Relativistic Electron Beams; Spectral Energy Distribution; X Ray Spectra; Astrophysics; BLACK HOLES; GALAXIES: NUCLEI; RADIATION MECHANISMS; SPECTROPHOTOMETRY full text sources ADS | data products SIMBAD (12) NED (12) MAST (1)