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arXiv · 0906.5253

The June 2008 flare of Markarian 421 from optical to TeV energies

R. M. Wagner·I. Donnarumma·J. Grube·M. Villata·C. M. Raiteri·C. -C. Hsu·K. Satalecka·E. Bernardini·P. Majumdar
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Abstract

We present optical to very-high energy (VHE) gamma-ray observations of Mrk 421 between 2008 May 24 and June 23. A high-energy (HE) gamma-ray signal was detected by AGILE-GRID during June 9-15, brighter than the average flux observed by EGRET in Mrk 421 by a factor of approx. 1.5. In 20-60 keV X-rays, a large-amplitude 5-day flare (June 9-15) was resolved with a maximum flux of approx. 55 mCrab. SuperAGILE, RXTE/ASM and Swift/BAT data show a clearly correlated flaring structure between soft and hard X-rays, with a high flux/amplitude variability in hard X-rays. Hints of the same flaring behavior is also detected in the simultaneously recorded GASP-WEBT optical data. A target of opportunity observation by Swift near the flare maximum on June 12-13 revealed the highest 2-10 keV flux ever observed (>100 mCrab) and a peak synchrotron energy of approx. 3 keV, a large shift from typical values of 0.5-1 keV. Observations at VHE (E>200 GeV) gamma-rays during June 6-8 show the source flux peaking in a bright state, well correlated with the simultaneous peak in the X-rays. The gamma-ray flare can be interpreted within the framework of the Synchrotron Self Compton model in terms of a rapid acceleration of leptons in the jet.

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R. M. Wagner, I. Donnarumma, J. Grube, M. Villata, C. M. Raiteri, C. -C. Hsu, K. Satalecka, E. Bernardini, P. Majumdar. 2009-06-29. The June 2008 flare of Markarian 421 from optical to TeV energies. https://arxiv.org/abs/0906.5253

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