If there are any black holes listening, can you just stop for a moment and give us time to breathe?
It wasn’t long after one of these supermassive star graves was captured on a special space camera that astronomers spotted the fastest growing black hole in the universe. And if recent reports are to be believed, astronomers have spotted an invisible black hole just outside Milky Way. Can we catch a break?
This new invisble black hole is a dormant one and is quietly minding it’s own business in a neighbouring galaxy called Large Magellanic Cloud, which is an unfortunate name for anything, including a galaxy.
According to the team of researchers that discovered this new black hole, this is the first time an inactive black hole outside our galaxy has been conclusively detected and identified.
A black hole’s extreme density produces an intense gravitational field that doesn’t even allow light to escape it. This is why they are shrouded in darkness and emit no light, making them virtually indetectable. But usually a black hole is ‘feeding’, causing a trace of X-Ray radiation to form around its horizon, making it possible to spot one. This is why inactive black holes (the ones that are not ‘feeding’, whatever that means in space terms!) are invisible unless you know how to look.
One of the ways to spot an invisible black hole, in case you have any black hole-spotting aspirations, is to observe the orbital movements of a star in a binary system. A binary system involves two stars revolving around each other. So if a stellar-mass black hole is present in a binary system, one of the stars would be orbitting an empty space, indicating the presence of a black hole in the system. The newly discovered black hole is a part of a binary system called VFTS243 and weighs nine times the mass of the sun. It’s event horizon is 27 km across. The companion that orbits this black hole is a hot blue star that weighs 25 times the mass of our sun.
The fact that an invisible black hole is often mistaken with other dark masses in space has led to the formation of an unofficial team of astronomers called the ‘Black Hole Police’ that works towards debunking black hole discoveries that are actually your garden variety dark masses and not the core of a collapsed star. In 2020, scientists claimed that they’ve discovered a black hole just a few thousand light years away from Earth, only for the Black Hole Police to debunk the claim and prove it was just another dark mass.
Astronomer Tomer Shenar from Amsterdam University, Netherlands, who is the leader of the team that discovered this black hole, is also a member of this Black Hole Police, along with fellow study co-authors Karem El-Badry of the Harvard and Smithsonian Center for Astrophysics and Julia Bodenstein of the European Southern Observatory (ESO). Shenar said that this was the first time his team was reporting a black hole discovery, instead of debunking it.
This discovery was made thanks to six years of observations obtained with the ESO’s Very Large Telescope (VLT). Aside from giving astronomers a deeper understanding of black holes, it also gives them a chance to study how black holes are formed in the first place.
“The star that formed the black hole in VFTS 243 appears to have collapsed entirely, with no sign of a previous explosion,” said Shenar, “Evidence for this ‘direct-collapse’ scenario has been emerging recently, but our study arguably provides one of the most direct indications. This has enormous implications for the origin of black-hole mergers in the cosmos.”
At this point, discoveries of black holes should be a drinking game. Take a shot every time someone discovers a scary black hole in the vicinity of Milky Way! There’s gotta be a silver lining somewhere.