Black hole boasts heavyweight jets | WPN World People News

Astronomers studying a black hole in our Galaxy with ESA’s XMM-Newton observatory have made a surprising discovery about the cocktail of particles that are ejected from its surroundings.

Black hole with disc and jets

Stellar-mass black holes are often found feasting on material from a companion star. Matter flows from the star towards the black hole, circling in a disc around it with a temperature so high that it emits X-rays.

The black hole can be a fussy eater: instead of swallowing all of the material, it sometimes pushes a fraction of it away in the form of two powerful jets of particles. Because these jets release mass and energy into the surroundings, the black hole has less material to feed on.

By studying the composition of the jets, we can learn more about the feeding habits of black holes.

Observations at radio wavelengths have already found that black hole jets contain electrons moving at close to the speed of light. But, until now, it was not clear whether the negative charge of the electrons is complemented by their anti-particles, positrons, or rather by heavier positively-charged particles in the jets, like protons or atomic nuclei.

In a new study, astronomers have used XMM-Newton to study a black hole binary system called 4U1630–47, well known to show outbursts of X-rays over periods of months and years.

“In our observations, we found signs of highly ionised nuclei of two heavy elements, iron and nickel,” says María Díaz Trigo of the European Southern Observatory in Munich, Germany.

“The discovery came as a surprise – and a good one, since it shows beyond doubt that the composition of black hole jets is much richer than just electrons.”

The team of astronomers observed 4U1630–47 with XMM-Newton on two occasions in September 2012, and compared the results with near-simultaneous radio observations from the Australia Telescope Compact Array.

Although the two sets of observations described by Dr Díaz Trigo and collaborators were separated by only a couple of weeks, the results were surprisingly different.

In the first set of observations, the astronomers detected X-rays from the accretion disc, but did not see anything in radio waves – a sign that the jets were not active.

But in the second set, they detected the source both in X-rays and radio waves, so they knew the jets had been reactivated in the meantime.

Source: European Space Agency