The ministry of communications

Cairo – Samia Sayed – In March 2021, a star was seen in a galaxy 250 million light-years away having a terrible, really bad day, according to RT.

And it was there on its own energetic, swept into the gravitational well of a supermassive black hole, and ripped apart into tiny pieces. We know this because many telescopes captured its view from Earth, as light from the event shot across the universe, the fifth-closest such event known. As the tidal disturbance event has ever been captured, the wealth of data obtained can help scientists better understand how black holes “feed”.

“Tidal disturbance events are a kind of cosmic laboratory. They are our real-time window into how a supermassive black hole lurking in the center of a galaxy is being fed,” says astronomer Sophie Jezari of the Space Telescope Science Institute.

Tidal disruption events are fairly rare, but we’ve seen enough of them to get a fairly detailed understanding of what happens when a star drifts past a black hole. Once the star is caught in the black hole’s gravitational field, tidal forces stretch and pull it to the point where it “flaps” (this is the “turbulence” part).

Then the star’s guts flow around the black hole in a chaotic manner, its fragments colliding with themselves and generating shocks that glow in multiple wavelengths. This process is not instantaneous, but might take weeks or months as the black hole devours the stellar debris.

The debris forms a disk that orbits the black hole, falling (or “accumulating”) onto it from the inner edge. When matter falls into a black hole, a structure called a halo can form between the inner edge of the accretion disk and the black hole’s event horizon.

This is a region containing extremely hot electrons that are thought to be powered by the black hole’s magnetic field, which acts like a synchrotron to accelerate the electrons to such high energies that they shine brightly at X-ray wavelengths.

Then powerful jets of plasma shoot out from the black hole’s polar regions, shooting halo material in opposite directions, sometimes at nearly the speed of light. These astrophysical jets are thought to form when matter accelerates along magnetic field lines outside the black hole’s event horizon; When you reach the poles, they explode.

Jets are not observed in all tidal disturbance events, but when they do occur, they are usually seen together. So when the transiting Zwicky facility caught a bright flash of the tidal disturbance event on March 1, 2021, later named AT2021ehb, NASA turned its NICER X-ray Observatory and its Rapid Observatory (X-ray, Gamma-Ray and Ultraviolet) to monitor the event’s development in hopes of capturing something interesting. Later, 300 days following Zwicky’s discovery, NuSTAR X-ray Observatory joined.

X-ray, ultraviolet, optical and radio radiation emitted from the event over a period of 430 days revealed that the culprit was a black hole regarding 10 million times the mass of the Sun.

But, well, there was something strange. None of the observatories detected any hint of jets. However, NuSTAR observations revealed the presence of a corona. Scientists say this strange discrepancy is very interesting.

“We’ve never seen a tidal disturbance event with X-ray emission like this without a jet, and that’s really amazing because it means we can separate what causes the jets and what causes the halo,” says astronomer Yuhan Yao of Caltech. Our observations of AT2021ehb are consistent with the idea that Magnetic fields have something to do with how the corona forms, and we want to know what makes this magnetic field so strong.”

Targets such as AT2021ehb make excellent laboratories for studying the formation and evolution of accretion discs and coronas in real time; And where there is one, there may be more. The researchers hope that they will be able to find more tidal disturbance events in the future, which will lead to answers regarding the role magnetic fields play in the formation of the corona. A bad day for a star 250 million years ago ended up being a very good day for human astronomers.