A few days ago news broke that NASA’s gamma ray satellite called Swift had detected what was possibly a burst of powerful gamma rays coming from the Andromeda galaxy (Messier 31), the closest large galaxy to our Milky Way galaxy.
This story still seems to be in the early stages, so I have not been able to find too much information as of yet, except that it has happened. Further analysis should show whether it was really a gamma ray burst, or a high energy x-ray event. Also, within the next few days, we should be able to detect an optical counterpart to this event, which will enable us to not only determine its precise location but also determine the nature of the object which has caused the burst.
If it is a gamma ray burst then this is tremendously exciting. There has not been a gamma ray burst anywhere like as close to us anytime in the 50-odd years that we’ve had the ability to detect them. Gamma ray bursts are amongst the most energetic phenomena in the Universe, and are thought to be associated with such cataclysmic events such as the explosion of a star (a supernova), the formation of a black hole or the merging of e.g. two neutron stars. I am crossing my fingers that this event is related to a supernova, because if it is it should be close enough to see very easily with the naked eye. However, although I haven’t looked into this, it would seem to me that a supernova would also have led to a huge flux of neutrinos, and to my knowledge no such neutrino flux has been detected, so maybe it isn’t a supernova. We shall have to wait and see.