Strange Black Hole Throws Astronomers For A Loop: Unclear How A Small Black Hole Is Creating So Much Light
An extremely bright black hole located 22 million light years away from Earth in the galaxy Messier 101 is baffling astronomers. Despite its (relatively) tiny size, this mysterious black hole is powering an energetic X-ray source in a neighboring galaxy and appears to have an impossible capacity to guzzle matter.
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The black hole system, called M101 ULX-1, is so bright that scientists originally thought it was a midsize black hole - a third size that would be somewhere in between the two current known varieties of black holds: the small stellar black holes scattered throughout galaxies, and the supermassive black holes found at galactic cores.
Intermediate black holes would have masses roughly between 100 and 1000 times the mass of the Sun, which have remained elusive so long, while M101 ULX-1 was looking like a promising contender. But the latest findings, published in Nature, show that this one is actually small, but is still shining almost twice as brightly than a black hole of its size should based on our current theories. This could change our thinking about the way black holes consume matter.
"Astronomers hoping to study these objects will now have to focus on other locations for which indirect evidence of this class of black holes has been suggested, either in the even brighter 'hyper-luminous' X-ray sources or inside some dense clusters of stars," said research team member Joel Bregman of the University of Michigan, in a press release.
The study looked also looked at X-ray sources give off high- and low-energy X-rays, or what the astronomers identify as hard and soft X-rays, respectively. Typically, larger black holes produce more soft X-rays, while smaller black holes give off more hard X-rays. The region around M101-ULX-1 should, theoretically, be dominated by hard X-rays and appear structurally more complicated, but its X-rays were dominated by soft X-rays. It defies the past logic and commonsense.
"Theories have been suggested which allow such low-mass black holes to eat this quickly and shine this brightly in X-rays. But those mechanisms leave signatures in the emitted X-ray spectrum, which this system does not display," said lead author Jifeng Liu, of the National Astronomical Observatories of China, Chinese Academy of Sciences. "Somehow this black hole, with a mass only 20-30 times the mass of our Sun, is able to eat at a rate near to its theoretical maximum while remaining relatively placid. It's amazing. Theory now needs to somehow explain what's going on."
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