First 'Rogue' Black Hole and First Supermassive Black Hole Ancestor Discovered

It was a two-fer week for black hole astronomers and both discoveries were ‘firsts’ – the first ever rogue supermassive black hole with no stars around it, and the first ancestor or precursor of a black hole that dates back to just 750 million years after the Big Bang. Did they celebrate with shots of Black Velvet?

“That’s how we knew we found a black hole. The object we detected is so massive that if it were a star, it would be shining brightly; yet we detected no light from it.”

In answer to the question he knew you would ask, Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore who led the study submitted to the Astrophysical Journal, revealed in Astronomy.com that his massive team of astronomers combined gravitational lensing and astrometry to detect the rogue black hole -- gravitational lensing changed the path of light shining behind it, while astrometry makes precise measurements of the position and mass of the object in front doing the blocking. The team needed the power of the Hubble Space Telescope to find this black hole because it was all alone with no nearby stars to attract their attention – a ‘rogue’ located about 5,200 light-years away. 

“By finding more that are isolated, we’ll be better able to understand what the true black hole population is like and learn even more about the ghosts that haunt our galaxy.” 

Sahu believes this new technique will help find more of the 100 million rogue black holes traversing our galaxy. 

Meanwhile, another team of astronomers found something completely different.

"The discovered object connects two rare populations of celestial objects, namely dusty starbursts and luminous quasars, and thereby provides a new avenue toward understanding the rapid growth of supermassive black holes in the early universe."

Seiji Fujimoto, a postdoctoral fellow based at the Niels Bohr Institute at the University of Copenhagen, was part of an international team of astrophysicists who discovered something that until now was just a theory – an object that may be the missing link between a galaxy and a quasar, which is a luminous active galactic nucleus (AGN) powered by a supermassive black hole. The object -- named GNz7q – was born during the Cosmic Dawn after the Big Bang, making it about 13.8 billion years old. 

“Theorists have predicted that these black holes undergo an early phase of rapid growth: a dust-reddened compact object emerges from a heavily dust-obscured starburst galaxy, then transitions to an unobscured luminous compact object by expelling the surrounding gas and dust.”

Team member Gabriel Brammer, an associate professor at Niels Bohr Institute, says in a press release (the results are published in the journal Nature) that GNz7q matched the theory thanks to a large amount of multi-wavelength datasets provided by the Hubble telescope for the so-called GOODS North sky field. While Hubble continues to show its worth, the team expects the new James Webb Space Telescope will have the power to find more of these ancestors of supermassive black holes. 

These two unique black hole discoveries -- a rogue and an ancestor -- prove once again it’s a great time to be an astronomer.