Detection of High-Energy Gamma-Ray Emission during the X-ray flaring activity in GRB100728A

TL;DR

This paper reports simultaneous Swift and Fermi observations of GRB100728A, revealing high-energy gamma-ray emission during X-ray flaring activity and discussing its implications for the burst's internal and external shock models.

Contribution

It provides the first detailed analysis of high-energy gamma-ray emission coinciding with X-ray flares in GRB100728A, linking prolonged central engine activity to broadband emission.

Findings

Detection of high-energy gamma-ray emission during X-ray flares

Evidence of GeV emission persisting after initial burst

Correlation between X-ray flares and gamma-ray activity

Abstract

We present the simultaneous Swift and Fermi observations of the bright GRB100728A and its afterglow. The early X-ray emission is dominated by a vigorous flaring activity continuing until 1 ks after the burst. In the same time interval high energy emission is significantly detected by the Fermi/LAT. Marginal evidence of GeV emission is observed up to later times. We discuss the broadband properties of this burst within both the internal and external shock scenarios, with a particular emphasis on the relation between X-ray flares, the GeV emission and a continued long-duration central engine activity as their power source.