(Credit: figure and text from EXOSAT slide set)
The hard X-ray light curve of the BL Lac object PKS 2155-304, seen with
the medium energy detectors on board EXOSAT. The variability is so rapid
(a factor of 10 in 6 hours) and the luminosity so high that relativistic
bulk motions, nearly along the line of sight, are probably occurring.
This is direct evidence of relativistic beaming.
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Last modified: Thursday, 26-Jun-2003 13:48:46 EDT
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