Intrinsic Curvature in the X-ray Spectra of BL LacertaeObjects

摘要

We report results from XMM-Newton observations of thirteen X-ray brightBL Lacertae objects, selected from the Einstein Slew Survey sample. The surveywas designed to look for evidence of either curvature or line features in the X-rayspectra. Previous data had suggested absorption features in the X-ray spectra ofsome BL Lacs; however, none of our spectra show convincing examples of lines,either in absorption or emission. We find significant evidence for a constant,likely intrinsic, curvature in 14 of 17 X-ray spectra. We model the curvature asresulting from episodic particle acceleration.