Optical Afterglow Observations of the Unusual Short-Duration Gamma-Ray Burst 040924

K. Y. Huang; Y. Urata; A. V. Filippenko; J. H. Hu; W. H. Ip; P. H. Kuo; W. Li; H. C. Lin; Z. Y. Lin; K. Makishima; K. Onda; Y. Qiu; T. Tamagawa

doi:10.1086/432612

arXiv · astro-ph/0506232

Optical Afterglow Observations of the Unusual Short-Duration Gamma-Ray Burst 040924

K. Y. Huang·Y. Urata·A. V. Filippenko·J. H. Hu·W. H. Ip·P. H. Kuo·W. Li·H. C. Lin·Z. Y. Lin·K. Makishima·K. Onda·Y. Qiu·T. Tamagawa

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Abstract

The 1-m telescope at Lulin Observatory and the 0.76-m Katzman Automatic Imaging Telescope at Lick Observatory were used to observe the optical afterglow of the short-duration (1.2--1.5 s) gamma-ray burst (GRB) 040924. This object has a soft high-energy spectrum, thus making it an exceptional case, perhaps actually belonging to the short-duration tail of the long-duration GRBs. Our data, combined with other reported measurements, show that the early R-band light curve can be described by two power laws with index alpha = -0.7 (at t = 16-50 min) and alpha = -1.06 (at later times). The rather small difference in the spectral indices can be more easily explained by an afterglow model invoking a cooling break rather than a jet break.

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K. Y. Huang, Y. Urata, A. V. Filippenko, J. H. Hu, W. H. Ip, P. H. Kuo, W. Li, H. C. Lin, Z. Y. Lin, K. Makishima, K. Onda, Y. Qiu, T. Tamagawa. 2005-06-10. Optical Afterglow Observations of the Unusual Short-Duration Gamma-Ray Burst 040924. https://doi.org/10.1086/432612

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