• Preliminary modeling shows that the newly launched jet is pointed directly at us.
• It moves at very close to the speed of light.
• It has unusually low magnetic field strength.

Earlier this year, astronomers were keeping tabs on data from an all-sky survey based at the Palomar Observatory in California when they detected an extraordinary flash in a part of the sky where no such light had been observed the night before. From a rough calculation, the flash appeared to give off more light than 1,000 trillion suns.

A team, led by researchers at NASA, Caltech, and elsewhere, posted their discovery to an astronomy newsletter, where the signal drew the attention of astronomers worldwide, including MIT scientists. Over the next few days, multiple telescopes focused in on the signal to gather more data across multiple wavelengths in the X-ray, ultraviolet, optical, and radio bands to see what could possibly produce such an enormous amount of light. Along with other observatories, India’s AstroSat gathered valuable data with its Soft X-ray Telescope and Ultraviolet Imaging Telescope that were used for the analysis.

Now the MIT astronomers and their collaborators have determined a likely source for the signal. In a study appearing in Nature Astronomy, the scientists report that the signal, named AT 2022cmc, is likely from a relativistic jet of matter streaking out from a supermassive black hole at close to the speed of light. They believe the jet is the product of a black hole that suddenly began devouring a nearby star, releasing a massive amount of energy in the process.

Astronomers have observed other “tidal disruption events,” or TDEs, in which a passing star is torn apart by a black hole’s tidal forces. AT 2022cmc is brighter than any TDE discovered to date. The source is also the farthest TDE ever detected, at some 8.5 billion lights years away — more than halfway across the universe.

How could such a distant event appear so bright in our sky? The team says the black hole’s jet may be pointing directly toward Earth, making the signal appear brighter than if the jet were pointing in any other direction. The effect is “Doppler boosting” and is similar to the amped-up sound of a passing siren.

AT 2022cmc is the first TDE discovered using an optical sky survey and the fourth Doppler-boosted TDE ever detected, and the first such event observed since 2011. “This particular event was 100 times more powerful than the most powerful gamma-ray burst afterglow. It was something extraordinary,” says the lead author Dheeraj Pasham, Research Scientist at MIT.

“We know there is one supermassive black hole per galaxy, and they formed very quickly in the universe’s first million years,” says co-author Matteo Lucchini, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “That tells us they feed very fast, though we don’t know how that feeding process works. Such sources like a TDE can be a good probe into how that process happens.”

“TDEs are short-lived, multiwavelength signatures of massive black holes’ activity at the nuclei of galaxies. India’s AstroSat mission, launched and operated by the Indian Space Research Organisation (ISRO), provides unique UV/X-ray capability for observing the brightest of these events. AT 2022cmc was exceptionally bright, AstroSat’s Soft X-ray Telescope (built by TIFR in collaboration with University of Leicester) revealed rapid X-ray variability on a scale of a few hours, requiring a compact emission region,” says co-author Gulab Dewangan, a faculty member at the Pune-based Inter-University Center for Astronomy & Astrophysics (IUCAA).

Lucchini’s MIT co-authors include first author Dheeraj “DJ” Pasham, Peter Kosec, Erin Kara, Ronald Remillard, and collaborators at universities and institutions worldwide including Gulab Dewangan and Priyanka Rani from IUCAA.

Contacts:

Gulab Dewangan (IUCAA, India) E-mail: gulab_at_iucaa.in Phone: +91-20-25604216

* please change _at_ to @

Team members: