Black hole “vomited” by the remains of a star “eaten” three years ago

(ORDO NEWS) — Astrophysicists first observed such an event – a powerful ejection of matter from the vicinity of a black hole three years after it literally tore apart a star with tidal forces.

Usually, the brightness of the radiation emitted by an accretion disk or jets increases almost immediately after they are replenished with material from a freshly absorbed celestial body.

When a star or other object gets very close to a much more massive body, such as a black hole, at some point they lose their integrity.

The “guest’s” own gravity ceases to hold its matter together – a so-called tidal disruption event (or flash) occurs ( TDE ).

The force of gravity of a black hole acts too differently on the side of the “careless” star closest to it than on the opposite side.

In 2018, the Automated Search for Supernovae ( ASAS-SN) telescopes detected a TDE in an unnamed galaxy ( 2MASS J10065085+0141342 ) approximately 665 million light-years from Earth.

A small star with a mass roughly equal to one-tenth of the Sun was too close to the supermassive black hole.

The event received the index AT 2018hyz , it was carefully observed for several months in a variety of radiation ranges and nothing extraordinary was noticed.

Only a few minor differences from other similar TDEs , otherwise the flash faded as usual.

Over the following years, AT 2018hyz was regularly checked during routine sky surveys, but no signs of unusual behavior appeared. Everything changed in June 2021.

According to Yvette Cendes , an assistant researcher at the Smithsonian Astrophysical Observatory, she and her colleagues had to resort to emergency measures in order not to miss the moment.

“Suddenly awake” TDE discovered the Very Large Array Antenna ( VLA ) radio telescope complex in New Mexico, USA.

The scientists immediately sent requests for extraordinary access to the instruments of other telescopes ( Director’s Discretionary Time, DDT ) to study the unique event in different spectra.

Astronomers around the world readily responded: the ALMA (Chile), MeerKAT (South Africa) and ATCA (Australia) radio telescope complexes , as well as the Neil Gehrels Swift Observatory and Chandra space X-ray observatories, peered into the anomalous delayed activity of AT 2018hyz.

An interesting picture emerged. 970 days after TDE , for reasons not fully understood, the accretion disk of an AT 2018hyz -associated black hole began ejecting matter.

Moreover, the speed of its outflow into the surrounding space reached half the speed of light. This is unusual for two reasons.

First, the TDE brightness reaches its maximum almost immediately after the start of the event, and then gradually decreases over several hundred days, but not longer than two years.

Secondly, in the process, some of the matter of the collapsed star can be ejected, but its speed does not exceed 20 percent of the speed of light.

Considering that over the past almost three years from the registration of AT 2018hyz to its re-activity, no stars fell on this black hole, the nature of the event raises questions.

Astrophysicists have proposed several hypotheses and performed corresponding simulations, but there is still no complete agreement with observations.

In general terms, the explanation boils down to the fact that the mass of the destroyed star that got into the accretion disk caused some kind of unstable processes or fluctuations.

And after almost a thousand Earth days, they poured into a bubble of gas or a jet, which was thrown away from the black hole.

An alternative idea is that the jet was there from the very beginning, but the substance of the collapsed star, which was immediately scattered around the surrounding space, shielded the relativistic jet.

True, this option is least of all consistent with the observational data of both 2018-19 and recent ones.


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