The X-ray afterglow of GRB 980519

¹ Istituto di Fisica Cosmica con Applicazioni all'Informatica, CNR, Via U. La Malfa 153, I-90146 Palermo, Italy
² Istituto Tecnologie e Studio Radiazione Extraterrestre, CNR, Via Gobetti 101, I-40129 Bologna, Italy
³ Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio Catone (RM), Italy
⁴ BeppoSAX Scientific Data Center, Via Corcolle 19, I-00131 Roma, Italy
⁵ Istituto Astrofisica Spaziale, CNR, Via Fosso del Cavaliere, I-00131 Roma, Italy
⁶ Dipartimento di Fisica, Università di Ferrara, Via Paradiso 11, I-44100 Ferrara, Italy

Received: 29 December 1998
Accepted: 10 March 1999

Abstract

Over a total of 20 gamma-ray bursts localized with arcmin accuracies, GRB 980519 represents the 13^th detected by the BeppoSAX Wide Field Cameras (WFCs). An X-ray TOO observation performed by the BeppoSAX Narrow Field Instruments (NFIs), starting about 9.5 hours after the high energy event, revealed X-ray afterglow emission in the 0.1-10 keV energy range. The flux decay was particularly fast with a power-law index of . This is the fastest decay so far measured. Signs of bursting activity are evident. The power-law spectral index of is quite soft but not unique among GRB afterglows. optical emission was detected as soon as 8 hours after the GRB and the power-law flux decay in all these bands were all consistent with . As for the X-ray, this is the fastest of all the 9 optically identified afterglows but GRB 980326. A candidate host galaxy with magnitude has been reported and variable radio emission detected.