Observation of strong variability in the X-ray emission from Markarian 421 correlated with the May 1996 TeV flare

Abstract

We observed the BL Lac object Markarian 421 with the X-ray satellite RXTE and the Whipple Air Cerenkov Telescope during a two week correlated X-ray/gamma-ray campaign in May 1996. Two dramatic outbursts with extremely rapid and strong flux variations were observed at TeV energies during this period. The X-ray emission in the 2–10 keV band was highly variable and reached a peak flux of 5.6×10−10 erg cm−2 s−1,5.6×10−10ergcm−2s−1, a historic high. Similar behavior was observed for the TeV emission. In contrast to earlier near-simultaneous X-ray/gamma-ray observations of Mrk 421, the variability amplitude is much larger at TeV than at X-ray energies. This behavior is expected in Synchrotron Self-Compton models. © 1997 American Institute of Physics.