BeppoSAX spectral survey of BL Lacs – New spectra and results

¹ INTEGRAL Science Data Centre, Chemin d' Ecogia 16, 1290 Versoix, Switzerland
² Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
³ Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
⁴ SISSA/ISAS, Via Beirut 2-4, 34014 Trieste, Italy

Corresponding author: V. Beckmann, Volker.Beckmann@obs.unige.ch

Received: 30 July 2001
Accepted: 28 November 2001

Abstract

We present BeppoSAX  LECS, MECS, and PDS spectra of eleven X-ray selected BL Lacertae objects. Combining these sources with the ones presented elsewhere we have a sample of 21 BL Lacs from the Einstein Medium Sensitivity and Einstein Slew Survey. The sample shows strong correlations of several physical parameters with the peak frequency of the synchrotron branch of the spectral energy distribution. In particular the peak frequency is correlated with the X-ray spectral shape: objects with the peak near to the X-ray band show harder and straighter X-ray spectra than those of the low energy peaked sources. This work shows that the recently proposed unification scenario for different types of blazars can hold also within the class of high frequency peaked BL Lac objects.