A supermassive black hole at the centre of a galaxy some 8.5 billion years way has ripped apart a nearby star, producing some of the most luminous jets ever seen.
When stars and other objects stray too close to a
supermassive black hole they are destroyed by the black hole’s immense gravity.
These occurrences, known as tidal-disruption events (TDEs),
result in a circling disk of material that is slowly pulled into the black hole
and very occasionally, as in the case of supermassive black hole AT2022cmc,
ejecting bright beams of material travelling close to the speed of light.
The Cerro Paranal mountain top is home to the world’s most
advanced ground-based facility for astronomy, hosting the four 8.2-metre Unit
Telescopes of the Very Large Telescope. Credit: ESO/G. Hüdepohl |
Luminous jets are produced in an estimated 1% of cases and
are known as a type of astronomical occurrence known as a transient, because
they are short-lived.
Bright flashes from the jets were spotted in data from the
Zwicky Transient Facility (ZTF) in February this year using a special new
technique which can comb through the equivalent of a million pages of
information every night.
Due to the rapid results produced by the novel data analysis
method, a research team in the US was able to swiftly follow up on the
transient event with multiwavelength observations of the system from different
observatory facilities.
The jets were visible across many wavelengths, from X-rays
to radio, and follow-up observations enabled the European Southern
Observatory’s Very Large Telescope to place AT2022cmc at a whopping distance of
8.5 billion light years away, while optical and infrared observation from
NASA’s Hubble telescope were able to precisely pinpoint AT2022cmc’s location.
“The last time scientists discovered one of these jets was
well over a decade ago,” said Michael Coughlin, an assistant professor of
astronomy at the University of Minnesota Twin Cities and co-lead on the paper
published in Nature. “From the data we have, we can estimate that relativistic
jets are launched in only 1% of these destructive events, making AT2022cmc an
extremely rare occurrence.”
Exactly why this behaviour is so rare remains an enigma,
however, the research team believe that AT2022cmc’s rapid spin powers the jets,
adding to the current understanding of the physics of these behemoth dead stars
at the centres of galaxies.
A black hole devours a star that has come too close. In very
rare circumstances, this may also result in jets moving with almost the speed
of light that generate light observed by our telescopes at many frequencies.
AT2022cmc is the most distant such event recorded to date. Credit: Zwicky
Transient Facility/R. Hurt (Caltech/IPAC) |
This detection – and the method used to discover it – are
valuable as a future models for astronomers as they scour the skies for more
events. “Scientists can use AT2022cmc as a model for what to look for and find
more disruptive events from distant black holes,” says lead author Igor
Andreoni, from the Department of Astronomy at UMD and NASA Goddard Space Flight
Centre.
This includes using ground-based optical surveys, as opposed
to gamma-ray observatories in space – how previous jets were primarily discovered.
“Our new search technique helps us to quickly identify rare
cosmic events in the ZTF survey data,” says Andreoni.
“And since ZTF and upcoming larger surveys such as VeraRubin’s Large Synoptic Survey Telescope scan the sky so frequently, we can now
expect to uncover a wealth of rare, or previously undiscovered cosmic events
and study them in detail. More than ever, big data mining is an important tool
to advance our knowledge of the universe”.