Abstract
We present X-ray spectra for the BL Lac objects PKS 0548-322 and 2A
1219+305 measured with the HEAO 1 A-2 detectors during pointing
maneuvers on 1978 September 30 and 1978 May 31, respectively. Both fit
single power-law components with low-energy absorption. For 2A 1219+305,
a thermal bremsstrahlung form gives an unacceptable fit. We find, from a
comparison with other statistically poorer observations taken at 6 month
intervals while the satellite was in its normal scanning mode, that the
sources exhibit spectral variability. A summary of measurements of the
five BL Lac objects detected with the A-2 experiment is presented, and
we conclude that X-ray spectral changes in this class of source are
common. Their general X-ray spectral characteristics distinguish BL Lac
objects from other classes of X-ray-emitting active galactic nuclei.
Analysis of their total spectra indicates that most of the energy is
emitted in the 5-100 eV band.
| Original language | English |
|---|---|
| Pages (from-to) | 53-59 |
| Journal | Astrophysical Journal |
| Volume | 243 |
| Publication status | Published - 1 Jan 1981 |
Keywords
- Bl Lacertae Objects
- Galactic Nuclei
- Variability
- X Ray Sources
- X Ray Spectra
- Heao 1
- Radio Sources (Astronomy)
- Spectral Bands
- Synchrotron Radiation
- Ultraviolet Radiation