The Prompt X-Ray Emission of Gamma-Ray Burst 980519

Open Access
Publisher Website
Google Scholar
Abstract
The prompt X-ray emission from gamma-ray burst (GRB) 980519, as measured with the Wide Field Cameras on board BeppoSAX, is characterized by a strong soft-to-hard-to-soft evolution. An analysis of the evolution of the X-ray spectrum in terms of a single power-law model shows that the photon index evolved from -2.0 to -1.1 to -2.4. The onset of the burst has such a soft spectrum that the 2-27 keV emission appears to precede the 107 keV emission of GRB 980519 (as measured with the Burst and Transient Source Experiment) by about 70 s. Nevertheless, we show that this early spectral variation is part of a smooth evolution over the whole burst and that there is no convincing evidence that the early X-rays originate from a physical process that is different from that giving rise to the remainder of the burst.