Earlier this year astronomers were monitoring data from the Zwicky Transient Facility, an all-sky survey based at the Palomar Observatory in California, when they detected an extraordinary flare in a part of the sky where no previous observed such a light the night before. By a rough estimate, the flash appeared to emit more light than 1,000 trillion suns. The team, led by researchers from NASA, Caltech and other centers, published their discovery in an astronomy newsletter, where the signal caught the attention of astronomers around the world, including scientists at MIT. In the days that followed, several telescopes zeroed in on the signal to collect more data at multiple wavelengths in the X-ray, ultraviolet, optical, and radio bands to see what such an enormous amount of light could produce.
Now, MIT astronomers, along with their collaborators, have determined a likely source of the signal. In a study appearing in Nature Astronomy, the scientists report that the signal, dubbed AT 2022cmc, likely comes from a relativistic jet of matter (also called a jet) exiting a supermassive black hole at close to the speed of light. . They believe the jet is the product of a black hole that suddenly started gobbling up a nearby star, releasing an enormous amount of energy in the process.
Astronomers have observed other “tidal disruption events,” or TDEs, in which a passing star is torn apart by tidal forces from a black hole. AT 2022cmc is brighter than any TDE discovered to date. The source is also the farthest TDE ever detected, some 8.5 billion light-years away, more than half the universe. How is it possible for an event so far away to appear so bright in our sky? The team says that the jet from the black hole may be pointing directly at Earth, making the signal appear brighter than if the jet was pointing in any other direction. This effect is called “Doppler amplification” and is similar to the amplified sound of a passing siren.
AT 2022cmc is the fourth Doppler shift TDE detected and the first such event to be observed since 2011. It is also the first TDE discovered using an optical survey of the sky. As more powerful telescopes come online in the coming years, they will reveal more TDEs, which may shed light on how supermassive black holes grow and shape the galaxies around them.
We know there is one supermassive black hole per galaxy, and that they formed very rapidly in the first million years of the universe, says co-author Matteo Lucchini of MIT’s Kavli Institute for Astrophysics and Space Research. That tells us that they feed very quickly, although we don’t know how that feeding process works. For this reason, sources such as the TDE can really be a good probe to know how this process occurs. Lucchini’s coauthors at MIT include first author and research scientist Dheeraj “DJ” Pasham, postdoc Peter Kosec, assistant professor Erin Kara, and principal research scientist Ronald Remillard, along with collaborators from universities and institutions around the world. world. Following the initial discovery of AT 2022cmc, Pasham and Lucchini zeroed in on the signal using the Neutron star Interior Composition ExploreR (NICER), an X-ray telescope operating aboard the International Space Station. Things seemed pretty normal for the first three days, Pasham recalls. Then we looked at it with an X-ray telescope, and what we found was that the source was too bright.
Sources Massachusetts Institute of Technology | CNRS | Pasham, D.R., Lucchini, M., Laskar, T. et al. The Birth of a Relativistic Jet Following the Disruption of a Star by a Cosmological Black Hole. Nat Astron (2022). doi.org/10.1038/s41550–022–01820-x