The MOA-11-191/OGLE-11-0462 microlensing event, observed from Hubble (Sahu et al., ArXiv, 2022).
An international team of researchers has received strong evidence that a possible microlensing event is due to a black hole wandering alone in interstellar space – the first ever observed.
The researchers posted a document describing their findings on the arXiv preprint server, OstanniPodii.com reports with reference to the Phys.org post.
Scientists have already speculated that many black holes roam the interstellar space, but they haven’t found any yet. This is due to the nature of black holes – they are difficult to see against the black background of space. However, the evidence for their existence was strong.
Previous research has shown that black holes often form when stars of a certain mass reach the end of their lives and their cores collapse, usually with supernova formation. Since many supernovae have been observed, it seemed clear that many black holes must form as a result.
It can be found through the lens effect, when starlight bends behind the black hole under the influence of its gravity. Due to the long distances, the effect of the lens is negligible, which makes it almost inapplicable even with the best modern telescopes.
But luck smiled in 2011 when two design teams searching for such a lens noticed a star that seemed to light up for no apparent reason. The researchers began intrigued by analyzing data from the Hubble Space Telescope.
For six years, they observed the change of light, hoping that the change was due to an increase in the black hole.
Then they found out something else – it seems that the position of the star has changed.
The researchers suggested that the change could only be related to an invisible moving object that exerts a force that attracts light as it passes, an interstellar black hole.
They continued to study the star and its light, and eventually ruled out the possibility that any light would come from the lens, and confirmed that the magnification was long, a prerequisite for confirming the existence of a black hole.
In general, the evidence is strong enough to confirm the observation of a free-swimming black hole.
Researchers were even able to measure its size – seven solar masses. Scientists also found that it is moving at a speed of about 45 km/s.
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