Supermassive black holes rip apart giant stars in a display that is brighter, more energetic, and more enduring than previously observed

April 25, 2023

(Nanowerk News) A distant star, dying a fiery and dramatic death, torn apart by a supermassive black hole in a corner of the forgotten sky. One of the most luminous, energetic, and long-lasting temporary objects flared up in the night sky, inspiring legends and launching civilizations. Instead, astronomers, acting as celestial supersleuths, find evidence of a star’s death throes where it has hidden undetected for years in computer-collected telescope datasets.

“That doesn’t make any sense. If you take an ordinary supernova and multiply it by a thousand times, we’re still not that bright – and supernovas are some of the brightest objects in the sky,” said Danny Milisavljevic, assistant professor of physics and astronomy at Purdue. University College of Science. “This is the most energetic phenomenon I have ever encountered.”

In astronomy, the objects that are the most luminous are often the most energetic. Milisavljevic, an expert on stellar life cycles – especially stellar deaths – noted that the data show highly anomalous observations.

The object, like all observed, is given a random name when it is found. Her name is ZTF20abrbeie, or, as astronomers affectionately call her, “Scary Barbie”. Barbie for the alphanumeric designation and “scary” because, Milisavljevic said, “It’s so foreign; its characteristics are terrifying!” “Scary Barbie” is the affectionate nickname astronomers call one of the most energetic and luminous transients ever observed: a supermassive black hole tearing apart a massive star, as in this illustration. (Image: Mark Garlick)

The object is what is known as a transient – ​​something observed in the sky that appears and then disappears or changes dramatically over hours or days, not centuries or millennia. In a new paper accepted for publication at Astrophysics Journal Letter (“Scary Barbie: Highly Energetic Long-Duration Tidal Disturbance Event Candidate No Host Galaxy Detectable at z=0.995”), Milisavljevic, his graduate student Bhagya Subrayan, and their team analyzed the data to conclude that the bright, long-lived transients are black holes eating stars. Subrayan’s research focuses on big data analysis of sky survey data.

“We think a supermassive black hole is pulling on a star and tearing it apart,” said Subrayan. “Forces around black holes, called tidal disturbances, pull other objects apart in a process called ‘spagetification’. We think that’s what happens, but at the extremes of timescales: the most massive black holes rip apart massive stars. Its duration is unlike anything we’ve seen before, and it produces the brightest transients in the universe.”

If Scary Barbie is so bright and famous, how is it only now coming to light, even though datasets suggest the first sighting occurred in 2020?

It hides in plain sight. While it is bright, it is also very far away and in a somewhat neglected corner of the sky. The anomaly was discovered using the Milisavljevic lab’s AI machine. The Recommender Engine For Intelligent Transient Tracking (REFITT) combs through observations from a number of telescopes around the world, including one built by the Zwicky Transient Facility using the Palomar Observatory in California.

“REFITT performs big data analysis,” says Milisavljevic. “It combs through millions of alerts and finds out what interesting things we might want to take a closer look at. This is a great example. Computers are really good at finding things when we can tell them exactly what to look for. But things like this, anomalous objects, even computers often don’t know to look for them. It doesn’t even have a template. It’s so different from anything else we’ve seen that we haven’t even gotten around to trying to classify it. It’s been hanging out on public data for years.

After the team and REFITT identified Scary Barbie as an interesting opportunity for research, they used data from other telescopes, including the Lick Observatory in California and the WM Keck Observatory in Hawaii. Spectrographic analysis from the telescope helped the team give names to the strange phenomena the data reported.

Scary Barbie is not only an order of magnitude brighter and more energetic than transient scientists have ever recorded before, but also outlasts transients are used to. Most transients last weeks or months, but this one has lasted more than 800 days – over two years – and the latest data available suggests it may be seen for years to come.

The event itself – the spaghettification of this massive star – may have been much shorter in duration, but because the transients are so far apart, the laws of relativity slow light as it travels to the human eye, making it appear to almost double in duration. long.

“There are few things in the universe that can be so strong, the reactions can last so long,” said Milisavljevic. “Discoveries like these really open our eyes to the fact that we are still unraveling mysteries and exploring wonders in the universe – things that no one has ever seen before.”

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