X-ray burst associated to FRB200428 with Insight-HXMT

Precise measurements of the timing and spectral properties of the X-ray bursts are helpful for understanding the physical origin of fast radio bursts. In this paper, we have reconstructed some information about the hard X-ray events, which were lost because the High Energy X-ray Telescope (HE) on board the Insight-HXMT mission was saturated by this extremely bright burst, and used the information to improve the temporal and spectral analyses of the X-ray burst.

The arrival times of the two X-ray peaks by fitting the new Insight-HXMT/HE lightcurve with multi-Gaussian profiles are 2.77+/-0.45ms and 34.30+/-0.56ms after the first peak of FRB 200428, respectively, while these two parameters are 2.57+/-0.52ms and 32.5+/-1.4ms if the fitting profile is a fast-rise and exponential decay function. The spectrum of the two X-ray peaks could be described by a cutoff power law with cutoff energy ~60keV and photon index ~1.4; the latter is softer than the result obtained in Li+ 2021NatAs...5..378L when the two X-ray peaks appeared.