Supernovae, gamma rays and primordial black holes — weird space phenomena that can kill

Primordial black holes

Our final interstellar nasty is perhaps the most speculative — yet by far the most sinister.

Black holes are regions where the very fabric of spacetime is so warped by concentrated mass that, beyond their “event horizon”, nothing — not even light — can escape their gravity.

In the conventional understanding of cosmic history, black holes were unable to form in the early universe — and only appeared, formed in the wake of supernova explosions, after the first generation of ancient stars had died.

However, a theory first proposed by the Soviet physicists Yakov Borisovich Zel’dovich and Igor Dmitriyevich Novikov in 1966 and developed by Stephen Hawking and his colleague Bernard Carr in the mid-seventies suggests that black holes could have formed relatively soon after the Big Bang.

Fluctuations in the density of the early universe, they argued, may have given regions of space enough mass to collapse in on themselves to form “primordial” black holes.

While controversial, this theory does have its attractive points. For instance, it might explain where all the “dark matter” is — the missing material needed to account for the discrepancy between the universe’s visible matter and the observed motion of the stars and galaxies.

Furthermore, primordial black holes, some researchers have argued, could have provided the gravitational kernels around which the first stars and galaxies formed — and also account for the excess of infra-red radiation that astronomers have detected coming from various distant sources across the universe.

If they do exist, we should soon be able to find out — thanks to NASA’s new James Webb Space Telescope and the ESA’s upcoming LISA gravitational wave detector, both of which should be able to pick up signals from primordial black holes.

Article source: https://www.express.co.uk/news/science/1696035/death-outer-space-supernovae-gamma-rays-primordial-black-holes-unlikely