Astronomers have discovered a black hole that was involved in a spectacular stellar feast about 9 billion light years away from us. A supermassive black hole with a mass about 10 million times that of the Sun was seen tearing apart a star about 9 times the size of our star and eating the remains of the star. This is the largest star ever destroyed in one of these bloody tidal disruption events (TDE). For comparison, the star in this TDE (AT2023vto) is five times more massive than the next most massive star astronomers have ever destroyed by a black hole.
As a result, AT2023vto is the largest and most brilliant object TDE astronomers have ever found. “What really sets TDE AT2023vto apart from other TDEs is its incredible brightness,” team member Yvette Sendes of the University of Oregon told Space.com. “It’s 9 billion light years away, and a little further away. It’s very far away, but it’s so bright that you can see it from afar. We usually see TDEs closer to home.” To be clear, this is not the most distant TDE ever observed. What sets these more distant (and therefore earlier) TDEs apart is that they eject jets of material at close to the speed of light. This makes them incredibly bright and easy to see from afar. TDE AT2023vto is like 99% of others in that it does not have a so-called relativistic jet, at least not yet. “This is the most distant TDE in this non-relativistic category to date, that’s for sure,” Sendes added.
“Studying this is very important to understand what happens when more mass is thrown into a black hole.” TDEs occur when the orbit of an unlucky star brings it too close to a supermassive black hole. The black hole’s immense gravitational influence causes strong tidal forces within the star (hence the “tidal disruption phenomenon”), simultaneously squashing the star horizontally and stretching it vertically. This turns the star into long strands of “plasma pasta,” a bloody process colorfully called “spaghettification.” “TDEs are interesting because they are essentially unique physics laboratories where we can test things that we can’t test on Earth,” Sendes explains.
“After all, here on Earth, we can’t just make a black hole and throw stuff in there. It’s always very exciting and interesting to investigate the differences between TDEs.” The actual TDE phenomenon lasts only a few hours, and the black hole only consumes a small fraction of the destroyed star. “When a TDE occurs, most of the star’s mass actually falls into the actual black hole,” Sendes said. “About half of the mass is just thrown outwards on this long orbit, and it never comes back. About half of the remaining mass forms an accretion disk around the black hole.” As a result, the supermassive black hole involved in the TDE suddenly goes from being very quiet, just an occasional clump of gas and dust, to being at the center of a very chaotic, crowded, bright environment, where the cosmic giant is visible from afar. Sendes noted that while it’s not entirely clear how the supermassive black hole at the center of AT2023vto feeds, it’s certain that its feeding habits have been very sparse, and the region around it was previously invisible from 9 billion light years away.
AT2023vto was first spotted by the Zwicky Transient Facility (ZTF) on September 9 as a sudden burst of light. The temporary phenomenon was initially misidentified as a Type II supernova, a cosmic explosion that occurs when a massive star rapidly collapses under its own gravity. Sendes explained that this error was cleared up when team leader Harsh Kumar, a researcher at the Harvard-Smithsonian Center for Astrophysics (CfA), examined the ZTF data. He modeled the light curve of the evolutionary emission, determined the true nature of AT2023vto, determined the masses of the stars and black holes involved, and calculated the distance to this TDE.
A pre-peer-reviewed version of the team’s findings is publicly available on the research paper repository arXiv.
source: https://arxiv.org/pdf/2408.01482