Study of X-ray and γ-ray flare from Mkn-421 during February 2010 using Swift and Fermi observations

In this work, we report on the intense flaring activity from Mkn-421 in X-ray and γ-ray regimes simultaneously observed by Swift-XRT/BAT and Fermi-LAT satellite telescopes in February 2010. With the aim of understanding the underlying physics of the flaring state in Mkn-421, we have performed a detailed spectral analysis of Swift/XRT and Fermi/LAT observations of Mkn-421 during February 12–25, 2010 (MJD 55239–55252). Over this period, we study the daily light curves and spectral variability of the source in 1–10 keV, 0.1–1 GeV and 1–100 GeV energy bands. We have performed the spectral analysis of Swift-XRT and Fermi/LAT observations to study the spectral evolution in the X-ray and gamma-ray energy domains respectively. We also compute the fractional variability amplitude in both the energy bands during the above period. We study trends between spectral parameters and physical insights provided by the parameter responsible for X-ray and γ-ray emission from the source. We search for energetic features phenomenologically linked to the single zone SSC model for blazar emission. We also produce the broad band SED with a leptonic single zone SSC model for the source.

► We study X-ray and gamma-ray flaring from Mkn-421 in February 2010. ► Swift/XRT/BAT and RXTE/ASM data show two flaring episodes. ► Swift/XRT (1–10 keV) flux is well correlated with Fermi/LAT (1–100 GeV) flux. ► Fermi/LAT energy band seems more variable than the Swift/XRT energy band. ► Clockwise sense of hysteresis loop in index-flux space indicates soft lag.