The discovery of a hidden nearby black hole may suggest that tens of thousands to millions more 'clandestine' black holes exist in our galaxy that have "gone unnoticed until now".
The object – VLA J213002.08+120904, or VLA J2130+12 for short – has been known by astronomers for several decades. But only after combining data from Nasa's Chandra Observatory, the Hubble Space Telescope and the National Science Foundation’s Karl G. Jansky Very Large Array did they realise that the object is "actually a nearby binary star system containing a low-mass star and a black hole". The star associated with the black hole has only around one-tenth to one-fifth the mass of our Sun.
The object is around 7,200 light years away – "well within" our own galaxy.
But because it lacks some of the "telltale signs" that binary black holes normally give off, scientists had not been able to identify its true nature.
"Usually, we find black holes when they are pulling in lots of material," said Bailey Tetarenko, a professor at the University of Alberta, Canada, who led the study. "Before falling into the black hole this material gets very hot and emits brightly in x-rays."
"This one is so quiet that it's practically a stealth black hole."
The study tracking VLA J2130+12 only covered a "very small patch of sky", meaning that there may be many more clandestine black holes in our galaxy – Nasa estimates that there are at least tens of thousands and potentially millions.
"Unless we were incredibly lucky to find one source like this in a small patch of the sky, there must be many more of these black hole binaries in our Galaxy than we used to think," said co-author Arash Bahramian of the University of Alberta.
And some of these undiscovered black holes may be "closer to Earth than we previously thought".
"There's no need to worry, however," said Bahramian. "Even these black holes would be many light years away from Earth."
A paper has been published in the Astrophysical Journal.
This article was originally published by WIRED UK
