HOW TO SWITCH A GAMMA-RAY BURST ON AND OFF THROUGH A MAGNETAR
- INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy)
- Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)
- INAF-IASF Milano, via E. Bassini 15, I-20133 Milano (Italy)
- GEPI-Observatoire de Paris, CNRS UMR 8111, Univ. Paris-Diderot, 5 Place Jules Jannsen, F-92190 Meudon (France)
- INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (RM) (Italy)
One of the most elusive features of gamma-ray bursts (GRBs) is the sporadic emission prior to the main prompt event observed in at least ∼15% of cases. These precursors have spectral and temporal properties similar to the main prompt emission, and smaller, but comparable, energetics. They are separated from the main event by a quiescent time that may be extremely long, and, in some cases, more than one precursor has been observed in the same burst. Precursors are still a puzzle: despite many attempts, none of the proposed models can account for all the observed features. Based on the complete sample of bright long GRBs observed by Swift (BAT6), we propose a new scenario for which precursors are explained by assuming that the central GRB engine is a newly born magnetar. In this model the precursor and the prompt emission arise from accretion of matter onto the surface of the magnetar. The accretion process can be halted by the centrifugal drag exerted by the rotating magnetosphere onto the infalling matter, allowing for multiple precursors and very long quiescent times.
- OSTI ID:
- 22270954
- Journal Information:
- Astrophysical Journal, Vol. 775, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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