Статья

Evidence for energy injection and a fine-tuned central engine at optical wavelengths in GRB 070419A

A. MelandriAstrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead Ch41 1LDC. GuidorziDipartimento di Fisica, Università di Ferrara, via Saragat 1, I‐44100 Ferrara, ItalyS. KobayashiAstrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead Ch41 1LDD. BersierAstrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead Ch41 1LDC. G. MundellAstrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead Ch41 1LDPeter MilneSteward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ, 85721 USAA. PozanenkoSpace Research Insitute (IKI), 84/32 Profoyuznaya Str, Moscow 117997, RussiaWenyu LiDepartment of Astronomy, University of California, Berkeley, CA, 94720-3411, USAA. V. FilippenkoDepartment of Astronomy, University of California, Berkeley, CA, 94720-3411, USAY. UrataDepartment of Physics, Saitama University, Saitama 338–8570, JapanM. IbrahimovUlugh Beg Astronomical Institute, Tashkent 700052, UzbekistanI. A. SteeleAstrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead Ch41 1LDA. GombocFaculty of Mathematics and Physics , University of Ljubljana , Jadranska 19, SI-1000, Ljubljana, SloveniaR. J. SmithAstrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead Ch41 1LDN. R. TanvirDepartment of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RHE. RolDepartment of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RHK. Y. HuangAcademia Sinica, Institute of Astronomy and Astrophysics, Taipei 106, Taiwan

Monthly Notices of the Royal Astronomical Societyjournal2009en

ABI

Аннотация

We present a comprehensive multiwavelength temporal and spectral analysis of the ‘fast rise exponential decay’ GRB 070419A. The early-time emission in the γ-ray and X-ray bands can be explained by a central engine active for at least 250 s, while at late times the X-ray light curve displays a simple power-law decay. In contrast, the observed behaviour in the optical band is complex (from 102 up to 106 s). We investigate the light-curve behaviour in the context of the standard forward/reverse shock model; associating the peak in the optical light curve at ∼450 s with the fireball deceleration time results in a Lorenz factor Γ≈ 350 at this time. In contrast, the shallow optical decay between 450 and 1500 s remains problematic, requiring a reverse shock component whose typical frequency is above the optical band at the optical peak time for it to be explained within the standard model. This predicts an increasing flux density for the forward shock component until t∼ 4 × 106 s, inconsistent with the observed decay of the optical emission from t∼ 104 s. A highly magnetized fireball is also ruled out due to unrealistic microphysic parameters and predicted light-curve behaviour that is not observed. We conclude that a long-lived central engine with a finely tuned energy injection rate and a sudden cessation of the injection is required to create the observed light curves, consistent with the same conditions that are invoked to explain the plateau phase of canonical X-ray light curves of γ-ray bursts.

Темы

Gamma-ray bursts and supernovae Astrophysics and Cosmic Phenomena Astro and Planetary Science

Идентификаторы

DOI: 10.1111/j.1365-2966.2009.14729.x

Цитирования и источники

Цитирований: 1 Использованных источников: 42

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