Search for very-high-energy photons from Gamma-ray bursts with HAWC

TL;DR

This paper reports on HAWC's search for very-high-energy photons from gamma-ray bursts, providing upper limits and insights into the VHE emission associated with these transient events.

Contribution

It presents the first results from HAWC's ongoing GRB monitoring program, including VHE upper limits for several notable bursts.

Findings

No VHE detection from the analyzed GRBs.

Established upper limits on VHE emission for multiple GRBs.

Demonstrated HAWC's capability for continuous GRB monitoring.

Abstract

Detections of very-high-energy (VHE; > 100 GeV) photons from Gamma-ray bursts (GRBs) can provide fundamental information on the involved radiative processes, physical composition of the ejecta and acceleration processes. The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is the best gamma-ray instrument to study transient phenomena over a long period of time from 100 GeV to 100 TeV. Its large field of view and duty cycle (> 95%) allow it to search blindly for sources of GRBs and to follow up on external alerts from satellite instruments, such as Fermi and Swift, searching for their VHE counterpart. We present results from the on-going GRB monitoring program and VHE upper limits of the latest interesting low-redshift and/or powerful bursts in HAWC's field of view: GRB 170206A, GRB 170817A, GRB 180720B and GRB 190114C.