Longest Duration X-ray Superflares ever observed on EQ Peg with AstroSat satellite



The longest duration X-ray Superflares ever observed on EQ Peg with AstroSat satellite is shown here. In the top panel, the background-subtracted AstroSat/SXT light curve of an M-dwarf binary EQ Peg is shown in 0.3–7 keV energy band. The temporal binning of the light curve is 200 s. The solid red line shows the superimposed best-fitting model to the light curve. While the cyan shaded region shows the 1σ variations from the best-fitting model. The grey shaded regions separated by the vertical dotted lines show the different time intervals for which time-resolved spectroscopy is performed. The approximate duration of the flares (F1, F2, and F3), the ‘Pre-flare’, and the ‘Post-Flare’ segments have been marked with black arrows. The red dot-dashed line is an extrapolated exponential curve that indicates the rise phase of flare F1. In the bottom panel, the (data model) residual have been plotted. The evenly distributed residuals along the horizontal line corresponding to zero residual indicate that the model curve does not seem to show any systematic deviation from the data.

[Image Credit: Karmakar et al. (2022)]