Gamma-Ray Bursts Observed by the Transiting Exoplanet Survey Satellite: Prompt Optical Counterparts and Afterglows of Swift-XRT Localized GRBs

TL;DR

This paper analyzes optical flashes and afterglows of eight GRBs observed by TESS, introduces a method to correct for cosmic ray effects, and discusses TESS's potential for early GRB optical detection.

Contribution

It presents the first detailed analysis of prompt optical emission from GRBs using TESS data and introduces a correction method for cosmic ray mitigation effects.

Findings

TESS detected optical flashes in several GRBs, providing new insights into prompt emission.

A correction method for TESS's cosmic ray mitigation improves brightness estimates.

Up to 10 GRBs per year could be observed by TESS within its field of view.

Abstract

Very few detections have been made of optical flashes contemporaneous with prompt high-energy emission from a gamma-ray burst (GRB). In this work, we present and analyze light curves of GRB-associated optical flashes and afterglows from the Transiting Exoplanet Survey Satellite (TESS). Our sample consists of eight GRBs with arcsecond-level localizations from the X-Ray Telescope on board the Neil Gehrels Swift Observatory. For each burst, we characterize the prompt optical emission and any observed afterglow, and constrain physical parameters for four of these bursts using their TESS light curves. This work also presents a straightforward method to correct for TESS's cosmic ray mitigation on 20-second timescales, which allows us to estimate the "true" brightness of optical flashes associated with prompt GRB emission. We also highlight TESS's continuous wide-field monitoring capability, which provides an efficient means of identifying optical emission from GRBs and characterizing early-time afterglow light curves. Based on empirical detection rates from Swift and the Fermi Gamma-Ray Space Telescope, up to 10 GRBs per year may fall within the contemporaneous TESS field of view.