Tucked within a small galaxy 1.8 billion light years away is an incredibly bright X-ray source known as XJ1500+0154. Data from three X-ray telescopes orbiting Earth revealed evidence of a “tidal disruption event” or TDE. Strong tidal forces from the intense gravity of a black hole can destroy an object that floats too close. In this case, a star.
As the star floats towards the black hole, the intense gravity of the black hole tosses pieces of it outward. But a nice chunk of the star continues towards the black hole. When the black hole begins to swallow up the star, stellar material is heated up to millions of degrees and creates an unmistakable X-ray flare.
Because XJ1500+0154 sits in the center its galaxy, the source is likely coming from a supermassive black hole.
Tidal disruption events like this one have been observed dozens of times since they were first observed in the 1990s. But this one is new. XJ1500+0154 feasted on this star for about a decade according to astronomers. More than ten times longer than the typical starry meal for a black hole.
“For most of the time we’ve been looking at this object, it has been growing rapidly,” said co-author James Guillochon of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “This tells us something unusual – like a star twice as heavy as our Sun – is being fed into the black hole.”
Scientists think they are observing the most massive star ever to be torn to pieces by a black hole, or they observed the entirety of a star being ripped apart.
The second option may be the case since the source was not detected by NASA’s Chandra X-ray Observatory on April 2, 2005. But it was detected soon after by the XMM-Newton on July 23rd, 2005. By June 5, 2008, the source’s brightness peaked during a Chandra observation. And since then, many observations have been made by Chandra, XMM-Newton and the Swift satellite of XJ1500+0154.
You can see how the luminosity spikes in mid-2005 and stays bright for a decade in the chart below.
Credit: Dr. Dacheng Lin/Chandra
Data gathered by the three telescopes shows the radiation from material around the black hole was regularly surpassing the Eddington limit. This is “defined by a balance between the outward pressure of radiation from the hot gas and the inward pull of the gravity of the black hole.”
“This even shows that black holes really can grow at extraordinarily high rates,” says co-author Stefanie Komossa. And the fast growth could help shed light on how supermassive black holes were able to reach masses a billion times higher than the sun when the universe was barely a billion years old.
The black hole will start wrapping up its stellar feast over the next decade based on modeling by the researchers. With less to munch on, XJ1500+0154’s luminosity should fade with it.
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