Recent X-ray observations of intermediate BL Lac objects

Abstract

We present recent ROSAT, ASCA and SAX observations of intermediate BL Lac objects (IBLs), i.e. BL Lacs which are located between high-energy and low-energy peaked BL Lac objects with respect to alpha_rx. Both the statistical properties of IBLs from the RGB sample and a detailed broad band X-ray spectral analysis of two objects (1424+2401, 1055+5644) point towards a continuous distribution of synchrotron emission peak frequencies among BL Lac objects.

4 pages, 4 figures; to appear in the proceedings of the conference "BL Lac Phenomenon" held in Turku, Finland, June 22-26, 1998