BeppoSAX follow-up search for the X-ray afterglow of GRB970111

TL;DR

This study used BeppoSAX to follow up on GRB970111, finding no bright X-ray afterglow and suggesting that gamma-ray brightness does not correlate with afterglow intensity, challenging previous assumptions.

Contribution

It provides the first detailed follow-up observation of GRB970111, revealing a faint or absent X-ray afterglow and questioning the link between gamma-ray peak flux and afterglow brightness.

Findings

No bright X-ray afterglow detected for GRB970111.

X-ray intensity is lower than expected based on other GRB afterglows.

No clear correlation between gamma-ray peak flux and X-ray afterglow brightness.

Abstract

The BeppoSAX satellite has recently opened a new way towards the solution of the long standing gamma-ray bursts' (GRBs) enigma, providing accurate coordinates few hours after the event thus allowing for multiwavelength follow-up observational campaigns. The BeppoSAX Narrow Field Instruments observed the region of sky containing GRB970111 16 hours after the burst. In contrast to other GRBs observed by BeppoSAX no bright afterglow was unambiguously observed. A faint source (1SAXJ1528.1+1937) is detected in a position consistent with the BeppoSAX Wide Field Camera position, but unconsistent with the IPN annulus. Whether 1SAXJ1528.1+1937 is associated with GRB970111 or not, the X-ray intensity of the afterglow is significantly lower than expected, based on the properties of the other BeppoSAX GRB afterglows. Given that GRB970111 is one of the brightest GRBs observed, this implies that there is no obvious relation between the GRB gamma-ray peak flux and the intensity of the X-ray afterglow.