Why are there no gamma-ray bursts detected in our galaxy?

  • I found from Wikipedia and other sites that there are no GRBs detected in the Milky Way. Can someone give a feasible reason for that? Why are there no GRBs detected in the Milky Way galaxy?

    - We are still alive. - The aliens who use them as close to lightspeed "starship" launchers have decided that we should be left alone yet a while.

    Pretty certain this is the "Law of Big Numbers" - GRBs are rare, we live in 1 galaxy, and there are near infinite number of galaxies we don't live in. Odds are very strong then that we won't see them in our Galaxy.

    This question seems to be based on a false premise: that there _should_ be frequent GRBs in our galaxy. Could you explain why you think this?

    Seems to be a pretty reasonable question to me. Voting to leave open.

    @OscarBravo, yes I believe that behind this should be a reason but the source of GRBs still a mystery, if we know that then we confidently enough answered that,

    @sundar3492 Ok - you think we should have frequent GRBs in our galaxy. Can you explain why? It seems to me that conventional wisdom is that GRBs are very rare and that we might never observe one in our galaxy.

    @OscarBravo, right now I have not exact answer that's why I am not posting here. But my current ongoing research on this topic. If I will succeed in my research on this topic, obviously I will post it here.

  • All models of gamma-ray bursts involve extremely energetic phenomena: particular types of supernovae, the coalescence of binary compact objects, strong magnetar flares, or tidal disruption events. It turns out that these events are quite rare - so rare, in fact, that GRBs would be expected to occur in a low-redshift Milky Way-like galaxy at a rate of only one every few million or tens of millions of years (Zhang & Meszaros 2003). If the Milky Way was undergoing a period of intense star formation, yielding more massive stars and therefore more supernovae, then this rate would go up, but still not significantly. Bear in mind that the Galactic supernova rate, for example, is believed to be only several supernovae per century, and the vast majority of supernovae don't lead to gamma-ray bursts.

    We know of many extragalactic GRBs for several reasons. It helps that we can observe large numbers of galaxies (thanks to how bright the bursts are), and if we could look at millions of Milky Way-like galaxies, it wouldn't be surprising if we could detect $\sim$1 event per year. (There's also the advantage that star formation peaked at a redshift $z\sim2$, and so high-redshift objects would be more likely to produce more GRBs!)

    The related aspect is that we can detect gamma ray burst over a large part of the universe. The largest distance measured is at z=8.2. link. Aside from measuring individual burst distance the uniform sky distribution tells us that they must be mostly very far away not to show any structure such as voids/super-clusters.

    The Soft Gamma-ray Repeater bursts are one class of gamma-ray bursts that are local. They originate from extreme magnetic field neutron stars aka magnetars. These bursts have different characteristics than the classical bursts : shorter duration, repeating and spectra that have proportionally more low energy photons in there x-ray to gamma-ray spectra.

    In particular, it's not odd that the Milky Way has provided no GRB observations, because only a tiny minority of the galaxies we've monitored have done so.

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Content dated before 7/24/2021 11:53 AM