Nearby gamma-ray bursts (GRBs) are likely to have represented a significant threat to life on the Earth. Recent observations suggest that a significant source of such bursts is compact binary mergers in globular clusters. This link between globular clusters and GRBs oers the possibility to find time intervals in the past with higher probabilities of a nearby burst, by tracing globular cluster orbits back in time. Here we show that the expected flux from such bursts is not flat over the past 550 Myr but rather exhibits three broad peaks, at 70, 180 and 340 Myr ago. The main source for nearby GRBs for all three time intervals is the globular cluster 47 Tuc, a consequence of its large mass and high stellar encounter rate, as well as the fact that it is one of the globular clusters which comes quite close to the Sun. Mass extinction events indeed coincide with all three time intervals found in this study, although a chance coincidence is quite likely. Nevertheless, the identified time intervals can be used as a guide to search for specific signatures of GRBs in the geological record around these times.

• Peak at 70 Myr: the famous KT extinction at 65 Myr BP, generally accepted to have had a significant role in the demise of the dinosaurs;
• Peak at 180 Myr: the late Pliensbachian/early Toarcian (early Jurrasic) extinction event at 179–186 Myr BP
• Peak at 340 Myr: the early Serpukhovian (mid Carboniferous) extinction event at 322–326 Myr BP, and the late Famennian (late Devonian) extinction event at 359–364 Myr BP.

Check full paper at http://arxiv.org/pdf/1303.3105.pdf