Abstract
Broad-range X-ray and gamma-ray spectra of the Seyfert galaxy NGC 4151
obtained by the UCSD/MIT and GSFC/CIT detectors of HEAO 1 are presented.
For two out of the three observational epochs the best-fit model is a
power law with photon index 1.6 + or - 0.1 in the 2 keV-2 MeV spectral
range. The third observation, in June, 1978, when the intensity was a
factor of 2 higher, requires a change above 50 keV from a similar power
law to a steeper power law or an exponential. Through comparisons with
previous observations, a weak correlation is found between the
high-energy spectral index and the flux level. Comparison of these data
and other X-ray and gamma-ray observations with the spectra expected
from several possible emission mechanisms supports a
synchrotron-self-Compton model using infrared target photons or a
Compton-scattering process involving X-rays of less than 10 keV
energies.
Original language | English |
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Pages (from-to) | 555-562 |
Journal | Astrophysical Journal |
Volume | 279 |
Publication status | Published - 1 Apr 1984 |
Keywords
- Gamma Ray Astronomy
- Seyfert Galaxies
- Spaceborne Astronomy
- X Ray Spectra
- Black Holes (Astronomy)
- Energy Spectra
- Galactic Nuclei
- Gamma Ray Spectra
- Heao 1
- Power Spectra
- Synchrotron Radiation