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R. Edelson (UCLA), R. G. Griffiths, S. Sembay, M. J. L. Turner (Univ. of Leicester), A. Markowitz (UCLA), R. S. Warwick (Univ. of Leicester), XMM EPIC Instrument Team
The bright, strongly variable BL Lac object PKS 2155-304 was observed by XMM/Newton for two uninterrupted periods of ~11 and 16 hr in 30-31 May 2000. The source showed much stronger variations in the hard (0.8-10 keV) band than the soft (0.1-0.7 keV) band. After scaling the variability amplitudes, the hard and soft light curves had very similar overall shapes and tracked well on >1 hr long time scales. They did however show significant detailed differences on shorter time scales. No significant interband lag was detected down to limits of < ~0.5 hr. These results will be compared with previous claims, based on lower signal/noise light curves interrupted on the 1.6 hr orbital period, that the hard X-rays led the soft by ~0.3-1.1 hr. They will also be interpreted in terms of the SSC emission model of blazars.
The author(s) of this abstract have provided an email address for comments about the abstract: rae@astro.ucla.edu