HEAO 1 observations of high-energy X-rays from 3C273
Abstract
The first detection of high energy (13 to 120 keV) X rays from the quasar 3C273, made by the HEAO 1 satellite, is reported. Observations were made with the 13 to 180 keV slat collimated detectors of the high energy X-ray and low energy gamma-ray (A4) experiment during December 1977-January 1978 and June-July 1978. Results are consistent with the previously observed X-ray flux variability on a scale of months. Photon count rates are presented for each of five energy bands and count rate and photon spectra for the June through July 1978 observations are derived. A comparison of the data obtained with that at lower X-ray energies and higher gamma-ray energies indicates that there is an overall spectral steepening from low to high energies and a possible break near 20 keV, which may be due to the gamma rays originating from a different region than that of the X rays.
- Publication:
-
Nature
- Pub Date:
- March 1979
- DOI:
- 10.1038/278234a0
- Bibcode:
- 1979Natur.278..234P
- Keywords:
-
- Gamma Ray Astronomy;
- Heao 1;
- Quasars;
- X Ray Sources;
- Emission Spectra;
- Photons;
- Astrophysics;
- GAMMA RAY ASTRONOMY;
- HEAO 1;
- QUASARS;
- X RAY SOURCES;
- EMISSION SPECTRA;
- PHOTONS