Prompt X-ray emission from Fast Radio Bursts -- Upper limits with AstroSat

Understand

Fast Radio Bursts (FRBs) are short lived ($\sim$ msec), energetic transients (having a peak flux density of $\sim$ Jy) with no known prompt emission in other energy bands.

• We present results of a search for prompt X-ray emissions from 41 FRBs using the Cadmium Zinc Telluride Imager (CZTI) on AstroSat which continuously monitors $\sim70\%$ of the sky.
• Our searches on various timescales in the 20-200 keV range, did not yield any counterparts in this hard X-ray band.
• We calculate upper limits on hard X-ray flux, in the same energy range and convert them to upper bounds for $\eta$: the ratio X-ray to radio fluence of FRBs.