High energy X-ray observations of extragalactic objects.
Abstract
Preliminary results are reported for scanning observations of the active galaxy NGC 5128 (Cen A) and the Type 1 Seyfert galaxy NGC 4151 with the low-energy detectors of the HEAO-1 A-4 hard X-ray instrument. The X-ray spectra in the energy range from 15 to 100 keV are shown to be consistent with previous observations of these galaxies. It is noted that NGC 5128 rose in intensity from 1972 to 1975, that spectral softening occurred after early 1973, and that the source has since decreased in intensity while maintaining an E to the -1.7 photon power law. The results for NGC 4151 indicate variable absorption below 10 keV and a power-law slope of about E to the -1.4 in the range from 10 keV to 10 MeV.
- Publication:
-
X-ray Astronomy
- Pub Date:
- 1979
- Bibcode:
- 1979xras.proc..373B
- Keywords:
-
- Galactic Radiation;
- Seyfert Galaxies;
- X Ray Sources;
- Active Galaxies;
- Galactic Nuclei;
- Heao 1;
- Spectrum Analysis;
- X Ray Astronomy;
- X Ray Spectra;
- X Ray Telescopes;
- Astrophysics;
- Active Galaxies:X-Ray Spectra;
- Seyfert Galaxies:X-Ray Spectra;
- X-Ray Sources:Extragalactic;
- X-Ray Sources:X-Ray Spectra