Energy distribution and variability of BL Lac objects: Recent observations and a theoretical scheme
Abstract
Spectral properties of X-ray selected and radio-selected BL Lacs are discussed. The results provide a direct indication that the X-ray emission is more isotropic than the radio emission. Recent results of multifrequency observations of the brightest X-ray selected BL Lac object, PKS 2155-304, are reviewed, showing how the fast X-ray variability is smeared out at low frequencies. A theoretical jet model is presented which can quantitatively account for the different spectral properties of X-ray selected and radio selected BL Lacs in terms of different line-of-sight angles to the jet.
- Publication:
-
Advances in Space Research
- Pub Date:
- 1988
- DOI:
- 10.1016/0273-1177(88)90389-4
- Bibcode:
- 1988AdSpR...8b..85M
- Keywords:
-
- Active Galactic Nuclei;
- Bl Lacertae Objects;
- Energy Distribution;
- Ultraviolet Astronomy;
- X Ray Astronomy;
- Astronomical Spectroscopy;
- Radio Emission;
- Radio Jets (Astronomy);
- Ultraviolet Spectra;
- Variability;
- Astronomy