The outburst comes from a tidal disruption event designated AT2018hyz, in which a star strayed too close to a black hole and was torn apart by intense gravitational forces in a process astronomers describe as spaghettification.
Researchers first spotted the event in 2018 with an optical telescope and initially classified it as an ordinary example of its kind, but years later they noticed that the previously quiet black hole had begun emitting an unusually strong signal in radio waves.
Led by University of Oregon astrophysicist Yvette Cendes, the team has now tracked the radio emission long enough to show that it is still rising sharply and is about 50 times brighter than when it was first detected in 2019.
Their latest analysis, reported in the Astrophysical Journal, indicates that the radiation is likely being funneled into a single jet, which would help explain why the event appeared unremarkable at early times if the jet was not yet pointed towards Earth.
Cendes and colleagues use highly sensitive radio observations from large facilities in New Mexico and South Africa to monitor the eruption, while faint visible light continues to glow from the region around the black hole.
From these measurements they calculated the current energy outflow and found that it rivals that of a gamma ray burst, putting it in the running as one of the most energetic single events ever observed in the cosmos.
To provide a sense of scale, the team compares the outpouring to estimates of the output of the fictional Death Star from Star Wars and concludes that the real black hole is emitting at least a trillion times more energy, and possibly up to 100 trillion times more.
The radio emission is expected to keep rising exponentially and could peak around 2027, giving astronomers a rare chance to watch a powerful jet evolve in real time and to test models of how black holes feed on disrupted stars.
The object, which Cendes informally calls Jetty McJetface in a nod to Boaty McBoatface, has already defied expectations about how long a tidal disruption event can stay active, and the team plans to keep following it to see how extreme it becomes.
Cendes is also searching archival data and new observations for other black holes that may show similarly delayed and long-lasting radio flares, arguing that such behavior might have been missed in the past because most follow-up campaigns end soon after an apparent explosion fades.
Winning observing time on major international radio telescopes is competitive, and proposals have traditionally focused on short-lived outbursts, but this event is prompting astronomers to rethink how long they keep watching after a star is torn apart.
Research Report:Continued Rapid Radio Brightening of the Tidal Disruption Event AT2018hyz
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