Rare Look at Black Hole Jets Yields Surprising Discoveries

A rare look at the jets ejected by a black hole has pulled back the curtains and allowed researchers to peer more closely at the mysterious phenomenon than ever before.

The object of study was a black hole just a few times more massive than the Sun and that was not believed to be active.

At first, radio observations failed to detect any jets; all was quiet on the X-ray side of things, too. A few weeks later, researchers returned to an entirely different picture. Jets had appeared along with corresponding radio emissions. Most surprising of all were lines in the X-ray spectrum around the black hole indicating the presence of "ordinary" atoms.

"Intriguingly, we found the lines were not where they should be, but rather were shifted significantly," James Miller Jones from the Curtin University node of the International Center for Radio Astronomy Research (ICRAR), who led the radio observations, said in a statement.

The researchers compare the effect to when a siren on a moving vehicle changes pitch as it moves away or toward us, shortening or lengthening the soundwave.

"It led us to conclude the particles were being accelerated to fast speeds in the jets, one directed towards Earth, and the other one in the opposite direction," said researcher Simone Migliari from the University of Barcelona.

According to Miller Jones, the study marks the first clear evidence that such particles are found in the jets emitted from a typical small black hole.

"We've known for a long time that jets contain electrons, but haven't got an overall negative charge, so there must be something positively charged in them too," Miller Jones said.

"Until now it wasn't clear whether the positive charge came from positrons, the antimatter 'opposite' of electrons, or positively charged atoms. Since our results found nickel and iron in these jets, we now know ordinary matter must be providing the positive charge."

Because positively charged atoms are much heavier than those positrons astronomers believed comprised the jets, the new finding suggests the streams pack far more energy than previously confirmed.

Finally, the new study has allowed researchers insight into the origins of the jets.

"Our results suggest it's more likely the disk is responsible for channelling the matter into the jets, and we are planning further observations to try and confirm this," Miller Jones said.