Black Hole Birth Kills Exploding Radio Star

Astronomers have discovered a new and unusual population of exploding stars. In fact, they've found that these stars "switch off" their radio transmissions before collapsing into a black hole. The findings reveal a little bit more about these strange stars which could help inform future studies.

Exploding stars use all of their energy to emit one last strong beam of highly energetic radiation, known as a gamma-ray burst. Until now, researchers believed that all gamma-ray bursts were followed by a radio afterglow. Yet this appears to not always be the case.

"After studying an ultra-sensitive image of gamma-ray bursts with no afterglow, we can now say the theory was incorrect and our telescopes have not failed us," said Paul Hancock, one of the researchers, in a news release.

In order to actually witness what was happening with these stars, the researchers stacked 200 separate observations on top of each other in order to recreate the image of a gamma-ray burst in much better quality. Despite this, though, there was no trace of a radio afterglow.

"In our research paper we argue that there must be two distinct types of gamma-ray burst, likely linked to differences in the magnetic field of the exploding star," said Hancock in a news release. "Gamma-ray bursts are thought to mark the birth of a black hole or neutron star--both of which have super-dense cores. But neutron stars have such strong magnetic fields (a million times stronger than those of black holes) that producing gamma-rays are more difficult. We think that those stars that collapse to form a neutron star have energy left over to produce the radio afterglow whereas those that become black holes put all their energy into one final powerful gamma-ray flash."

Currently, the researchers are planning on seeing if there are other subtle ways in which the two types of bursts differ. Yet the latest findings give them a whole new look at gamma-ray bursts and reveal that being wrong sometimes is more interesting than being right.

The findings are published in The Astrophysical Journal.