ROSAT observations of radio-selected BL Lac objects
Abstract
ROSAT observations of a homogeneous sample of radio-selected BL Lac objects are presented. Results of a detailed spectral analysis in the soft ~0.1-2.0 keV energy range are discussed and compared with similar previously published results. The X-ray spectral shape is discussed in relation to the overall energy distribution, with particular emphasis on the high-energy gamma-ray emission recently detected by the Compton Gamma-Ray Observatory (CGRO) EGRET detector for about half of the objects in the sample. Dividing the objects in our sample on the basis of the radio-to-X-ray flux ratio (alpha_rx), we show that objects with a_rx<~0.75 have flatter X-ray spectra and are likely to be stronger gamma-ray emitters than objects with a_rx<0.75. Moreover, we note that the value of the peak energy of the synchrotron component, in a nu-nuf_v plot, correlates with a_rx and a_x.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 1995
- DOI:
- 10.1093/mnras/277.1.297
- arXiv:
- arXiv:astro-ph/9506128
- Bibcode:
- 1995MNRAS.277..297C
- Keywords:
-
- BL LACERTAE OBJECTS: GENERAL;
- X-RAYS: GALAXIES;
- X-RAYS: GENERAL;
- Astrophysics
- E-Print:
- to appear on MNRAS, 18 pages (latex file plus 5 tables and 3 figures) uuencoded compressed tar postscript files