Matter falling into a black hole at 30 percent of the speed of light

As a direct result, gas in-fall – accretion – onto black holes must be powering the most energetic phenomena in the Universe.

This is the characteristic disc structure from the simulation of a misaligned disc around a spinning black hole. Credit: K. Pounds et al. / University of Leicester
This is the characteristic disc structure from the simulation of a misaligned disc around a spinning black hole. Credit: K. Pounds et al. / University of Leicester

A UK group of space experts report the main recognition of matter falling into a black hole at 30% of the speed of light, situated in the center of the billion-light-year-distant galaxy PG211+143. The group, driven by Professor Ken Pounds of the University of Leicester, utilized information from the European Space Agency’s X-ray observatory XMM-Newton to observe the black hole.

The center of almost every galaxy contains a supermassive black hole, with masses of millions to billions of times the mass of our Sun. With adequate matter falling into the hole, these can turn out to be amazingly glowing and are viewed as a quasar or active galactic nucleus (AGN).

However black holes are so compact that gas is almost always rotating too much to fall indirectly. Instead, it orbits the hole, approaching gradually through an accretion disc — a sequence of circular orbits of decreasing size. As gas spirals inwards, it moves faster and faster and becomes hot and luminous, turning gravitational energy into the radiation that astronomers observe.

The orbit of the gas around the dark opening is regularly thought to be lined up with the rotation of the black hole, however, there is no convincing purpose behind this to be the situation. Indeed, the reason we have summer and winter is that the Earth’s daily rotation does not agree with its yearly circle around the Sun.

Prof. Pounds, from the University of Leicester’s Department of Physics and Astronomy, said: “The galaxy we were observing with XMM-Newton has a 40 million solar mass black hole which is very bright and evidently well fed. Indeed some 15 years ago we detected a powerful wind indicating the hole was being over-fed. While such winds are now found in many active galaxies, PG1211+143 has now yielded another ‘first’, with the detection of matter plunging directly into the hole itself.”

“We were able to follow an Earth-sized clump of matter for about a day, as it was pulled towards the black hole, accelerating to a third of the velocity of light before being swallowed up by the hole.”

As of recently, it has been misty how misaligned rotation may influence the in-fall of gas. This is especially pertinent to the sustaining of a supermassive black hole since matter (interstellar gas clouds or even detached stars) can fall in from any heading.

For this study, scientists used data from XMM-Newton and observed X-ray spectra from the galaxy PG211+143. This object lies in excess of one billion light-years away toward the direction of the constellation Coma Berenices and is a Seyfert cosmic system, described by a very bright AGN coming about because of the nearness of the massive black hole at its nucleus.

The researchers found the spectra to be strongly red-shifted, showing the observed matter to be falling into the black hole at the enormous speed of 30 percent of the speed of light, or around 100,000 kilometres per second. The gas has almost no rotation around the hole and is detected extremely close to it in astronomical terms, at a distance of only 20 times the hole’s size (its event horizon, the boundary of the region where escape is no longer possible).

The observation concurs intimately with ongoing hypothetical work, additionally at Leicester and utilizing the UK’s Dirac supercomputer facility mimicking the ‘tearing’ of misaligned growth circles. This work has demonstrated that rings of gas can break off and collide into one another, offsetting their rotation and leaving gas to fall straightforwardly towards the black hole.

A further implication of the new research is that ‘chaotic accretion’ from misaligned discs is likely to be common for supermassive black holes. Such black holes would then spin quite slowly, being able to accept far more gas and grow their masses more rapidly than generally believed, providing an explanation for why black holes which formed in the early Universe quickly gained very large masses.

The study is published in the journal Royal Astronomical Society.