Gaia Could Detect Free-Floating Black Holes Passing Near Stars in the Milky Way

The thing with black holes is they’re hard to see. Typically we can only detect their presence when we can detect their gravitational pull. And if there are rogue black holes simply traveling throughout the galaxy and not tied to another luminous astronomical, it would be fiendishly hard to detect them. But now we have a new potential data set to do so.  

Gaia just released its massive 3rd data set that contains astrometry data for over 1.5 billion stars, about 1% of the total number of stars in the galaxy. According to a new paper by Jeff Andrews of the University of Florida and Northwestern University, it might be possible for Gaia to detect perturbances caused by a rogue black hole briefly interacting with one of the 1.5 billion stars in the catalog. Unfortunately, it’s just not very likely that any such interaction actually took place during Gaia’s observing time.

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Hubble Pins Down the Mass of a Potential Free-Floating Black Hole That’s 5,000 Light-Years Away

This is an artist’s impression of a black hole drifting through our Milky Way galaxy. The black hole is the crushed remnant of a massive star that exploded as a supernova. The surviving core is several times the mass of our Sun. The black hole traps light because of its intense gravitational field. The black hole distorts the space around it, which warps images of background stars lined up almost directly behind it. This gravitational "lensing" effect offers the only telltale evidence for the existence of lone black holes wandering our galaxy, of which there may be a population of 100 million. The Hubble Space Telescope goes hunting for these black holes by looking for distortion in starlight as the black holes drift in front of background stars. Credit: ESA

Earlier this year, astronomers used microlensing and the Hubble Space Telescope to detect, for the first time, a rogue black hole that is about 5,000 lightyears away from Earth. Now, with more precise measurements, they have been able to determine an approximate mass of this hard-to-detect object. However, the surprisingly low mass means there’s a chance this object may not actually be a black hole.

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The First Rogue Black Hole has Been Discovered, and it’s Only 5,000 Light-Years Away

Microlensing strikes again.  Astronomers have been using the technique to detect everything from rogue planets to the most distant star ever seen.  Now, astronomers have officially found another elusive object that has long been theorized and that we first reported on back in 2009 but has never directly detected – a rogue black hole.

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