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The optical afterglow of the short gamma-ray burst GRB 050709

Jens Hjorth·Darach Watson·Johan P. U. Fynbo·Paul A. Price·Brian L. Jensen·Uffe G. Jørgensen·Daniel Kubas·Javier Gorosabel·Páll Jakobsson·Jesper Sollerman·Kristian Pedersen·Chryssa Kouveliotou
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Abstract

It has long been known that there are two classes of gamma-ray bursts (GRBs), mainly distinguished by their durations. The breakthrough in our understanding of long-duration GRBs (those lasting more than ~2 s), which ultimately linked them with energetic Type Ic supernovae, came from the discovery of their long-lived X-ray and optical afterglows, when precise and rapid localizations of the sources could finally be obtained. X-ray localizations have recently become available for short (duration <2 s) GRBs, which have evaded optical detection for more than 30 years. Here we report the first discovery of transient optical emission (R-band magnitude ~23) associated with a short burst; GRB 050709. The optical afterglow was localized with subarcsecond accuracy, and lies in the outskirts of a blue dwarf galaxy. The optical and X-ray afterglow properties 34 h after the GRB are reminiscent of the afterglows of long GRBs, which are attributable to synchrotron emission from ultrarelativistic ejecta. We did not, however, detect a supernova, as found in most nearby long GRB afterglows, which suggests a different origin for the short GRBs.

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Jens Hjorth, Darach Watson, Johan P. U. Fynbo, Paul A. Price, Brian L. Jensen, Uffe G. Jørgensen, Daniel Kubas, Javier Gorosabel, Páll Jakobsson, Jesper Sollerman, Kristian Pedersen, Chryssa Kouveliotou. 2005-10-04. The optical afterglow of the short gamma-ray burst GRB 050709. https://doi.org/10.1038/nature04174

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