Rare cosmic event flashed light at Earth 8.5 billion light-years away

An incredibly bright flash that appeared in the night sky in February was the result of a star getting too close to a supermassive black hole, meeting its untimely end there when it was torn to pieces.

But the rare cosmic event actually occurred 8.5 billion light-years away from Earth, when the universe was just a third of its current age – and it raised more questions than it answered.

The signal from the bright burst, known as AT 2022cmc, was first picked up by the Zwicky Transient Facility at the California Institute of Technology’s Palomar Observatory on February 11.

When a star is torn apart by the tidal gravitational forces of a black hole, this is known as a tidal disruption event. Astronomers have observed such violent events before, but AT 2022cmc is brighter than anything previously discovered. It is also the most distant ever observed.

bright lights

Astronomers believe that when the black hole engulfed the star, it released an enormous amount of energy and sent a jet of material streaking through space at close to the speed of light.

It is likely that AT 2022cmc appeared so bright in our sky because the jet was pointed directly at Earth, creating what is known as the “Doppler-boosting” effect.

The discovery could reveal more about the growth of supermassive black holes, as well as how they eat stars. Two separate studies detailing the event were published in the journals Nature Astronomy and nature on Wednesday.

Typically, gamma-ray bursts, the powerful bursts of X-rays released when massive stars collapse, explain the brightest flashes in the night sky.

“Gamma-ray bursts are the usual suspects for events like this,” said Nature Astronomy study co-author Dr. Benjamin Gompertz, who led the gamma-ray burst comparison analysis for the paper, in a statement.

“However, as bright as they are, there is a limited amount of light a collapsing star can produce. Because AT 2022cmc was so bright and lasted so long, we knew something truly gigantic must be powering it – a supermassive black hole,” said Gompertz, assistant professor at the University of Birmingham in the UK.

Astronomers used the Interior Neutron Star Composition ExploreR, or NICER, an X-ray telescope on the International Space Station, to analyze the signal.

The researchers determined that AT 2022cmc was “100 times more powerful than the most powerful gamma-ray afterglow” recorded previously, according to Dheeraj Pasham, lead study author of the Nature Astronomy paper and research scientist at the Institute of Technology in Massachusetts Kavli Institute for Astrophysics and Space Research.

First, the star was ripped to pieces, then pieces of it were pulled into the spinning disk orbiting the black hole’s point of no return.

The extreme X-rays released by the event were created as the fragmented star spun into a whirlpool of debris as it fell into the black hole.

a rare event

The Zwicky Transient Facility is one of the largest used to study the universe and spy on unusual cosmic events.

After first spotting the signal, several dozen other ground and space telescopes focused on AT 2022cmc, providing an incredibly detailed view of the rare event.

The Very Large Telescope at the European Southern Observatory in Chile helped determine its distance from Earth, while the Hubble Space Telescope captured the infrared and visible light released by the event. The Karl G. Jansky Very Large Array of telescopes in New Mexico picked up radio waves.

Only about 1% of tidal disruption events result in relativistic jets (or beams that move close to the speed of light) that hurl plasma and radiation from the poles of a rotating black hole.

In this illustration, a black hole pulls material from a neighboring star onto an accretion disk.

“The last time scientists discovered one of these jets was over a decade ago,” Michael Coughlin, an assistant professor of astronomy at the University of Minnesota Twin Cities and study co-lead author of the Nature paper, said in a statement.

Astronomers still don’t understand why some tidal disruption events create these jets while others don’t — but it’s possible that the black hole needed to spin particularly fast to create a jet in the first place.

Observing more events like this could reveal how black holes hurl such powerful jets through space, according to the researchers.

“Astronomy is changing rapidly,” Igor Andreoni, a postdoctoral associate in the department of astronomy at the University of Maryland, College Park, and study co-lead author of the Nature paper, said in a statement. “Scientists can use AT 2022cmc as a model for what to look for and find more distant black hole disruptive events.”