An ultraluminous black hole that exists in the neighboring Pinwheel Galaxy has been discovered by astronomers, which shines twice as bright as previously thought possible.
The ultra-bright object, which exists in a system called ULX-1, that resides about 22 million light-years from Earth, may alter traditional thinking regarding how black holes radiate energy. Joel Bregman of the University of Michigan said in a statement, "As if black holes weren’t extreme enough, this is a really extreme one that is shining as brightly as it possibly can. It’s figured out a way to be more luminous than we thought possible."
The ULX-1 system, which includes the bright black hole, along with a companion star, is short for "ultraluminous X-ray source." A team led by Jifeng Liu, of the Chinese Academy of Sciences in Beijing, has been studying ULX-1 using the Gemini Observatory in Hawaii and two NASA spacecraft, the Hubble Space Telescope and the Chandra X-ray Observatory.
ULX-1 generates extreme amounts of high-energy X-ray light, which is emitted by material on a downward spiral into the black hole's maw. The light is so intense that astronomers initially figured that ULX-1 was an intermediate-mass black hole. Though, the latest findings suggest that the black hole is actually quite small by black hole standards. "Our findings may turn the trend of taking ultraluminous X-ray sources as promising intermediate black hole candidates," Liu said in a statement.
Spectroscopic analysis has shown that the companion star in ULX-1 is a big, hot type known as a Wolf-Rayet star, coming in at 19 times the mass of the sun. It was also found that the star and the black hole orbit each other once every 8.2 days. This rate of orbit allowed Liu's team to estimate the black hole's mass at being between 20 to 30 times that of the sun. These measurements put ULX-1 at a stellar-size black hole range, not an intermediate one.
Though no middleweight black hole has been found regarding ULX-1, researchers believe that this intermediate-mass class makes up the building blocks of the supermassive black holes that exist in the center of most, if not all, galaxies.
Researchers likewise aren't sure how the ULX-1 system manages to put off so much light. "Our work shows, based on our conclusion of a stellar mass black hole, that our understanding of the black hole radiation mechanism is incomplete and needs revision," Liu said.
The full study appears in the journal Nature.
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