black holes in milky way galaxy

London, Jan 23 : A new study by astronomers has suggested that tiny black holes at the centre of our galaxy could be a possible source of the mysterious antimatter present in the Milky Way.

According to a report in New Scientist, astronomers know the galactic centre is awash in antimatter because it generates a vast cloud of gamma rays when it collides with normal matter.

But none of the proposed explanations for the antimatter's source - which include supernovae, X-ray emitting binary stars and the decay of bizarre dark matter - seem to precisely fit the bill.

Now, researchers have proposed that colossal numbers of ancient, evaporating black holes might supply the antimatter in the galaxy.

Astronomers have long known that there are legions of tiny black holes at the centre of the galaxy, which were created during the big bang and then wandered off in space, slowly evaporating in a process termed Hawking radiation.

The rate at which they evaporate depends on their mass - the more massive the black hole, the fewer particles it can evaporate away.

The new study suggests that if the primordial black holes have a mass of around 1016 grams - about the same mass as an average-sized asteroid, they will naturally produce the correct amount of antimatter to explain observations.

According to lead author Cosimo Bambi of Wayne State University in Detroit, Michigan, US, up to 1024 primordial black holes could exist in the centre of the galaxy.

In this quantity, they could even provide a significant fraction of the cosmological dark matter that astronomers believe outweighs normal matter throughout the universe.

The new study also suggests a way to test the hypothesis that the galaxy's antimatter originates in primordial black holes. ambi has calculated the number of particles - other than positrons - that would be radiated from black holes with a mass of 1016 g and found out that they would produce a noticeable increase in the diffuse glow of high energy (MeV) gamma rays towards the centre of the galaxy.

But, according to Bambi, it may be difficult to observe the radiation because the amount of time needed to make a definitive measurement would be prohibitive.

ANI