First ever detection of monster black hole collision, 150 times heavier than the Sun
Black holes are massive, right? The first pair of black holes detected were each about 30 times more massive than the Sun. When they merged, the resulting ‘remnant’ was a black hole that was a whopping 60 times more massive than the Sun.
Astronomers from the LIGO and Virgo Scientific Collaboration (LVC) have reported the first ever direct observation of the most massive black hole merger to date. Two monster black holes collided to form an even more massive object—an intermediate-mass black hole, about 150 times as heavy as the Sun.
Researchers from the Monash University School of Physics and Astronomy, and the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) contributed to the detection and used the computing resources of the new Gravitational-Wave Data Centre to infer the masses of the merging black holes.
Juan Calderón Bustillo—co-author and OzGrav postdoctoral researcher at Monash University—said:
“This is the first time we’ve observed an intermediate-mass black hole, almost twice as heavy as any other black hole ever observed with gravitational-waves. For this reason, the detected signal is much shorter than those previously observed. In fact, it’s so short that we can barely observe the black hole collision, we can only see its result.”
The online detection team at the University of Western Australia detected the event, GW190521, seconds after the gravitational-wave data were available, and helped generate public alerts for the LIGO Scientific Collaboration.
Since gravitational waves directly measure the masses of the colliding black holes, this measurement should be much more robust than the similar mass black hole previously reported by Liu et al. (published in the journal Nature last year).
We are witnessing the birth of an intermediate mass black hole: a black hole more than 100 times as heavy as the Sun, almost twice as heavy as any black hole previously observed with gravitational-waves. These intermediate mass black holes could be the seeds that grow into the supermassive black holes that reside in the centres of galaxies.
OzGrav Chief Investigator and co-author David Ottaway, from University of Adelaide, said this was a huge step towards understanding the link between the smaller black holes that had been seen by gravitational-wave detectors and the massive black holes that are found in the centre of galaxies.
These gravitational waves came from over 15 billion light years away! But isn't the Universe only around 14 billion years old, you ask? It turns out that the Universe was actually around 7 billion years old when these two black holes collided. As the gravitational waves rippled out through the Universe, the Universe was expanding.
Consequently, the measured distance to this collision is now further than the product of the speed of light and the time travelled—mind (and space) bending stuff! This shows gravitational waves are able to probe the ancient history of the Universe, when galaxies were forming stars at a rate around 10 times higher than the present day.