A team of scientists have confirmed the existence of a lone black hole that has no star orbiting it in the Milky Way galaxy. Based on observations from the Hubble Space Telescope, the study, published in the Astrophysical Journal earlier this month, establishes the identity of the stellar object the team had discovered several years ago.
In 2022, Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore and his colleagues discovered a "dark object" meandering in the Sagittarius constellation. However, their findings at the time were disputed, with a section of scientists claiming the body was instead a neutron star.
However, the team continued studying the object and has now found more evidence backing up their original claim that it is likely a lone black hole. Having peered through the data between 2011 to 2017 for their initial attempt, the researchers looked through the data between 2021 and 2022 from Hubble as well as the Gaia space probe, to make better assertions.
Notably, prior to the current finding, all black holes that scientists have ever identified have been spotted with a companion star. Since black holes 'suck' all the light, it is difficult to spot them, if not for the presence of a companion star due to an effect called gravitational lensing.
However, Mr Sahu and his team managed to notice the black hole after it passed in front of a distant non-companion star, magnifying its light and shifting its position in the sky for a short while. They found that the 'dark object' they were pursuing was approximately seven times as massive as the sun -- showing that it could not be a neutron star.
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The lone black hole is located 5,000 light-years away from Earth, which is much closer than the supermassive black hole, Sagittarius A*, located at the centre of the Milky Way, 27,000 light-years away.
Based on the findings, Mr Sahu and his team are hoping to find more examples, using the Nancy Grace Roman Space Telescope, which is scheduled to launch in 2027.
