An ultra-distant black hole "eats" half of the sun every year and throws the "residues" to the earth!

The artist's concept above shows a supermassive black hole greedily devouring a star and throwing out the debris. (Image credit: Carl Knox - OzGrav, ARC Centre of Excellence for Gravitational Wave Discovery, Swinburne University of Technology)

A wave of stellar debris is hurtling toward Earth, and astronomers have determined the culprit is a distant black hole that swallowed the star whole, sending its fragments flying across the depths of space.

The jets are pointed directly at Earth, and the black hole's tearing of the star apart can be seen in visible light, which astronomers call a tidal disruption event (TDE). The extreme events are usually only detectable in high-energy light such as gamma rays and X-rays, and this discovery could mark a new way to observe such events.

When a star passes too close to a black hole, the black hole's gravity creates strong tidal forces that tear the star apart. In about 1% of TEDs, the black hole ejects plasma and radiation from its poles.

"Ejective TEDs are very strange, but we know very little about them because we have only seen a limited number of them," Neil Tanvir, an astronomer at the University of Leicester in the United Kingdom, said in a statement released by the observatory in the new study, using a telescope at the Southern Observatory. "So astronomers have been searching for similar extreme events to understand how jets are created and why only a small fraction of TEDs produce jets."

In February 2022, astronomers observed a TED and named it "AT2022cmc". At that time, the Zwicky Transient Source Detection Facility (ZTF), a survey telescope in California, issued an alert for detecting an unusual visible light source. Subsequently, the Very Large Telescope (VLT) of the Southern Observatory in the Atacama Desert in northern Chile monitored it. For astronomers, this is a common process: survey telescopes like ZTF look for signs of short and extreme events in the sky, while telescopes like VLT can observe in more detail and follow up on events.

AT2022cmc initially resembled a gamma-ray burst (GRB), the most powerful source of electromagnetic radiation in the known universe, whose origin remains a mystery. Thanks to these rare explosions of light, astronomers have commissioned various telescopes, including the VLT with its X-ray spectrograph. In total, 21 telescopes observed the AT2022cmc event in different wavelengths of light, including the Hubble Space Telescope and the Neutron Star Interior Composition Explorer (NICER) X-ray instrument on the International Space Station.

The above artist's illustration shows the X-ray beams produced when a black hole devours a star, releasing other types of electromagnetic waves. (Image source: Zwicky Transient Facility/R.Hurt (Caltech/IPAC))

The large amount of data revealed two strange observations. First, the source of AT2022cmc is very far away from Earth, and the light began its journey when the 13.8 billion-year-old universe was only one-third of its current age. Second, the event was not a gamma-ray burst.

Results from the NICER X-ray instrument showed that the signal was 100 times brighter than the afterglow of any gamma-ray burst observed to date. "Things looked normal for the first three days, but when we looked with X-ray telescopes, we saw that the source was way too bright. This is extraordinary!" said Dhiraj Parsham, an astrophysicist at the Massachusetts Institute of Technology and the study's lead author, in a statement.

The above artist's illustration depicts a supermassive black hole tearing apart a star and ejecting the remaining stellar matter into jets. (Image credit: ESO/M.Kornmesser)

A total of 21 telescopes around the world observed AT2022cmc in different bands, from high-energy gamma rays to low-energy radio waves. Astronomers then compared these data with observations of other "violent" events, such as stellar collapses and powerful cosmic explosions called "kilonovae."

The only cases that match the light profiles recorded by these telescopes are rare instances where a TDE jet - containing material moving at 99.99% the speed of light - is pointed towards Earth.

"Because the jet is pointed directly at us, the event is much brighter than it would otherwise appear and is visible across a wider range of the electromagnetic spectrum," George Leloudas, an astronomer at the Technical University of Denmark and co-author of the study, said in the ESO statement.

Artist's impression of a supermassive black hole tearing apart a star. (Image credit: ESO/M. Kornmesser)

Despite this, the jets are still so bright that astronomers have calculated that the black hole is eating about half the mass of the sun every year, Parsham said. “A lot of this tidal disruption happens early in the event, and we were able to catch it right at the beginning, within a week after the black hole starts feeding on the star,” he added.

The fact that this TDE event was very far away from Earth wasn't the only record-breaking aspect of AT2022cmc. Previously, ejected TDEs like this have only been seen in high-energy radiation such as gamma rays and X-rays, but this is the first time such a violent star-killing event has been seen in visible light.

Observing AT2022cmc in visible light could therefore open up a whole new way to probe the TDEs produced by these jets, allowing for more in-depth studies.

BY:Robert Lea

FY: Busy North Gate

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