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Centaurus A (NGC 5128) at 2 keV--2. 3 MeV: HEAO 1 observations and implications

Journal Article · · Astrophys. J.; (United States)
DOI:https://doi.org/10.1086/158719· OSTI ID:6386709
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The nearby active-nucleus galaxy Centaurus A (NGC 5128) has been studied at 2 keV--2.3 MeV using data from both the UCSD/MIT hard X-ray and low energy ..gamma..-ray instrument and from the GSFC/CIT cosmic X-ray experiment on HEAO 1. We find that an E/sup -1.60plus-or-minus0.03/ power law spectrum breaking to E/sup -2.0plus-or-minus0.2/ at 140 keV best describes the 1978 January and July data. The average intensity was 50% higher during the January observations. We have searched our data for faster variations and set limits in several energy ranges over times from fractions of a day to several days. Upper limits to unresolved lines at 511 keV and 1.6 MeV are 6.5 x 10/sup -4/ photons cm/sup -2/ s/sup -1/ and 2.2 x 10/sup -4/ photons cm/sup -2/ s/sup -1/, respectively, at the 90% confidence level. Continuation of the observed power law to higher energies is used to constrain various models of energy generation in the nucleus of NGC 5128.
Research Organization:
Department of Physics and Center for Astrophysics and Space Science, University of California at San Diego
OSTI ID:
6386709
Journal Information:
Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 244:2; ISSN ASJOA
Country of Publication:
United States
Language:
English

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Related Subjects

640103* -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BASIC INTERACTIONS
BLACK HOLES
COMPTON EFFECT
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
EMISSION
GALAXIES
GALAXY NUCLEI
INTERACTIONS
RADIO GALAXIES
SCATTERING
SPECTRA
STAR ACCRETION
STAR EVOLUTION
VARIATIONS
X-RAY GALAXIES
X-RAY SPECTRA