X-ray selected BL Lacertae objects: catalogue and statistical properties

The present work focuses on the statistical properties of X-ray selected BL Lacertae objects (XBLs) whose catalogue has been compiled. It consists of 312 sources from different X-ray surveys, unambiguously identified to mid-2010. Results of the statistical research of different observational quantities (redshift, multiwavelength luminosities, host/nucleus absolute magnitudes, central black hole masses, synchrotron peak frequencies, broadband spectral indices) are also provided and existence of the correlation between them is proved. Overall flux variability shows an increasing trend towards larger frequencies. XBLs are found to be much less active in sense of intra-night optical variability as compared to radio-selected BL Lacs (RBLs). A separate list of 106 XBL candidates including the same characteristics for each source as in the case of XBL catalogue was also created.