X-ray intensity and spectral variations in the BL Lac sources H 2155-304 and PKS 0548-322.
Abstract
The results from the X-ray observations of two BL Lacertae objects, H2155-304 and PKS0548-322, are presented. The observations were carried out with the HEAO-1 A2 Low Energy Detectors, the High Resolution Imager, and the Monitor Proportional Counter aboard the Einstein Observatory. Correlated X-ray intensity variations of about 20 percent in the 0.15-3.5 keV energy band and about 40 percent in the 1.5-10 keV energy band are observed in H2155-304 over a period of about 8 hr. A factor of two change in the intensity of PKS0548-322 in the 3.5-10 keV energy interval is also detected over a time interval of 1 hr. Variations in the X-ray intensity over a timescale of months and the hardening of the spectrum with increasing intensity are seen in the HEAO-1 A2 data on H2155-304. The shortest observed timescale for the variability is used to derive an upper limit on the mass of the central accreting source in the two BL Lac objects studied here.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 1987
- DOI:
- 10.1093/mnras/227.2.525
- Bibcode:
- 1987MNRAS.227..525A
- Keywords:
-
- Bl Lacertae Objects;
- Periodic Variations;
- Radiant Flux Density;
- Spaceborne Astronomy;
- Spectral Energy Distribution;
- X Ray Spectra;
- Astronomical Spectroscopy;
- Heao 1;
- Heao 2;
- Light Curve;
- Satellite-Borne Instruments;
- Temporal Distribution;
- Astronomy