THE LATE PEAKING AFTERGLOW OF GRB 100418A

Marshall, F.; Antonelli, L.; Burrows, D.; Covino, S.; DE PASQUALE, Massımılıano; Evans, P.; Fugazza, D.; Holland, S.; Liang, E.; O'Brien, P.; Oates, S.; Osborne, J.; Pagani, C.; Sakamoto, T.; Siegel, M.; Wu, X.; Zhang, B.

doi:10.1088/0004-637x/727/2/132

THE LATE PEAKING AFTERGLOW OF GRB 100418A

Marshall F. E., Antonelli L. A., Burrows D. N., Covino S., DE PASQUALE M., Evans P. A., ...More

ASTROPHYSICAL JOURNAL, vol.727, no.2, 2011 (SCI-Expanded, Scopus)

Publication Type: Article / Article
Volume: 727 Issue: 2
Publication Date: 2011
Doi Number: 10.1088/0004-637x/727/2/132
Journal Name: ASTROPHYSICAL JOURNAL
Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
Keywords: gamma-ray burst: individual (GRB 100418A), GAMMA-RAY BURST, LIGHT CURVES, SWIFT OBSERVATIONS, TELESCOPE, REM, IDENTIFICATION, CALIBRATION, EVOLUTION, EMISSION, SPECTRA
Istanbul University Affiliated: Yes

Abstract

GRB 100418A is a long gamma-ray burst (GRB) at redshift z = 0.6235 discovered with the Swift Gamma-ray Burst Explorer with unusual optical and X-ray light curves. After an initial short-lived, rapid decline in X-rays, the optical and X-ray light curves observed with Swift are approximately flat or rising slightly out to at least similar to 7 x 10(3) s after the trigger, peak at similar to 5 x 10(4) s, and then follow an approximately power-law decay. Such a long optical plateau and late peaking is rarely seen in GRB afterglows. Observations with Rapid Eye Mount during a gap in the Swift coverage indicate a bright optical flare at similar to 2.5 x 10(4) s. The long plateau phase of the afterglow is interpreted using either a model with continuous injection of energy into the forward shock of the burst or a model in which the jet of the burst is viewed off-axis. In both models the isotropic kinetic energy in the late afterglow after the plateau phase is >= 10(2) times the 10(51) erg of the prompt isotropic gamma-ray energy release. The energy injection model is favored because the off-axis jet model would require the intrinsic T-90 for the GRB jet viewed on-axis to be very short, similar to 10 ms, and the intrinsic isotropic gamma-ray energy release and the true jet energy to be much higher than the typical values of known short GRBs. The non-detection of a jet break up to t similar to 2 x 10(6) s indicates a jet half-opening angle of at least similar to 14 degrees, and a relatively high-collimation-corrected jet energy of E-jet >= 10(52) erg.