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Multifrequency emission from hot ion disksThe discovery of a large number of gamma-emitting active galactic nuclei (AGNs) by the EGRET instrument on the Compton Gamma Ray Observatory (CGRO) has spawned a lot of theoretical interest in the high-energy and multifrequency emission from these objects. Since most of them show evidence for relativistic outflow, jet models have received most of the attention so far. However, the presence of soft photons at the center of the active nucleus and the resulting Compton drag make it difficult to produce the observed amount of MeV/GeV emission. We explore hot, two-temperature accretion disks around Kerr black holes as an alternative to relativistic beam models for the production of the high-enerty emission. The decay of neutral pions created in the hot region produces photons with energies up to several hundred MeV. Relativistic pairs created as a result of charged pion decays produce additional inverse-Compton radiation in the range of approx. 1 keV-4 MeV if the pairs are exposed to UV radiation, or in the range of approx. 40 keV-150 MeV if the pairs are exposed to soft X-rays. This suggests that high-energy flares in AGNs may be triggered by changes in the disk structure (such as phase transitions or the development of electron scattering coronae) that temporarily shield the hot inner region from UV photons emitted at larger radii, thereby reducing the optical depth for MeV/GeV gamma-rays. Stochastic processes may also play a role in accelerating the utrarelativistic electrons responsible for producing the highest energy (GeV) emission.
Document ID
19950031533
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Maisack, Michael
(Univ. Tuebingen Tuebingen, Germany)
Becker, Peter A.
(George Mason Univ. Fairfax, VA, US, United States)
Kafatos, Menas
(George Mason Univ. Fairfax, VA, US, United States)
Date Acquired
August 16, 2013
Publication Date
June 1, 1994
Publication Information
Publication: The Astrophysical Journal Supplement Series
Volume: 92
Issue: 2
ISSN: 0067-0049
Subject Category
Astronomy
Accession Number
95A63132
Funding Number(s)
CONTRACT_GRANT: DARA-50-OR9205 4
Distribution Limits
Public
Copyright
Other

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