On calibrations using the crab nebula and models of the nebular X-ray emission

Abstract

Motivated by a paper of Kirsch et al. on possible use of the Crab Nebula as a standard candle for calibrating X-ray response functions, we examine consequences of intrinsic departures from a single (absorbed) power law upon such calibrations. We limit our analyses to three more modern X-ray instruments - the ROSAT/PSPC, the RXTE/Proportional Counter Array, and the XMM-Newton/EPIC-pn (burst mode). The results indicate a need to refine two of the three response functions studied. We are also able to distinguish between two current theoretical models for the system spectrum. © 2010 The American Astronomical Society.