Personal View site logo
Gamma rays and dinosaurs
  • 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

  • 7 Replies sorted by
  • Interesting. I've scanned a few pages of the document but I have yet to see the direct cause of extinction events via the gamma rays. I find it interesting because (related to the global warming debate in the other thread) scientists have found that cosmic rays seed cloud cover and therefor increase or decrease warming and could directly change climate enough for extinction level events. I could see that gamma rays could do the same although one is atomic nuclei and the other is photon based.

  • Interesting. I've scanned a few pages of the document but I have yet to see the direct cause of extinction events via the gamma rays.

    This paper is not about it. It is about modelling trajectories of Solar system and globular cluster 47 Tuc. They found out that big changes in habitat coincide with time when sun was closest to this cluster.

    As for cause of issues to health you need to consult biologist. Gamma bursts can be very strong.

  • Are we doomed yet? :P Any possible link to the arctic melting?

  • Are we doomed yet? :P Any possible link to the arctic melting?

    We are. :-)

    Btw most probable bad thing is sun flares. Big sun flares are much more frequent than all other bad stuff.

  • Oh oh giant sun flares through the giant breach in Earth's Magnetic over the Arctic?

  • Oh oh giant sun flares through the giant breach in Earth's Magnetic over the Arctic?

    Get some reading on it.

  • If gamma rays are so bad how come they made the Hulk? Check and checkmate, bitches.