Scientists may have discovered the first “free-floating” black hole as it orbits our Milky Way galaxy.
When big stars collapse, they are thought to leave black holes behind. If that is the case, there must be hundreds of millions scattered throughout the Milky Way left behind by the deaths of these stars.
But scientists are struggling to find them. Isolated black holes are invisible.
Researchers now believe they have spotted such a “free-floating” black hole flying through the galaxy at 100,000 miles per hour. It was spotted using gravitational microleading, in which scientists observe the distortion of light caused by the object’s gravity.
The object is in our galaxy, but it is still thousands of light years away. However, the discovery suggests that statistically the closest such object to us should be less than 80 light years away.
This is somewhere between 1.6 and 4.4 times the mass of our Sun, according to a set of scientists. Another using the same data estimates it is closer to 7.1 solar masses.
Smaller size estimates mean that the object may still be a neutron star instead of a black hole. But with the latest, bigger calculations, this will certainly be a black hole.
Whatever it is, the object is the first such “ghost” – the dark, dense remnants of a dead star – that has ever been seen roaming our galaxy, unpaired with another star.
“This is the first free-floating black hole or neutron star detected by gravitational microlensing,” said Yeshika Lou of UC Berkeley, one of the leaders of one of the studies.
“With microlensing, we are able to explore these lonely, compact objects and weigh them. I think we have opened a new window to these dark objects that cannot be seen in any other way. “
The separate study of two competing teams means that the study is described in two articles: one, by the UC Berkeley team, which it believes is smaller, was published in the Astrophysical Journal Letters, while the other, a larger evaluation by the Research Institute for space telescopes is described in The Astrophysical Journal.
In addition to evaluating different masses, the teams disagree on how far the site is likely. The UC Berkeley team estimates it to be between 2,280 and 6,260 light-years away, while the STSci team estimates it is about 5,153 light-years away.
This also means that the site has received two different names: MOA-2011-BLG-191 and OGLE-2011-BLG-0462, or OB110462 for short.
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