Astronomers Find Light Created by Black Hole Merger

Astronomers working in California say they may have discovered evidence of light emitted from the merger of two black holes. If their findings are confirmed by future studies, then this marks the first-ever observation of light ejected by the smashing together of the two massive, celestial bodies. The discovery may also stand as possible evidence that black holes aren’t solely born in dark “stellar graveyards.”

Caltech / R. Hurt 

The possible evidence of light emitted from a black hole merger, which comes via Gizmodo, was outlined in a paper recently published in the journal Physical Review Letters. The authors of the paper, including Matthew Graham at the California Institute of Technology, et al., noted that the hypothesis for this phenomenon was developed after LIGO detected gravitational waves from a candidate binary black hole merger in May of 2019.

For those who need a refresher, LIGO, or the Laser Interferometer Gravitational Wave Observatory, is the facility that confirmed in 2016 “the [first-ever] observation of a binary black hole merger.” (It was big news.) Following the possible binary black hole discovery in 2019, Graham developed a unique theoretical model to explain the event. He essentially asked the question, “What if this black hole merger happened inside of a quasar?”

A quasar (pictured immediately below) is essentially a supermassive black hole actively pulling in dust and gas from a surrounding accretion disk. In the process, it lights up the gas and dust to the point of being super-luminous. Graham hypothesized that the binary black hole merger observed in 2019 took place inside the accretion disk of one of these quasars.

To test the hypothesis, the paper’s authors combed through archival data from the California-based Zwicky Transient Facility (ZTF), which identifies astronomical objects that quickly change in brightness at visible wavelengths. They took that data and compared it to the alerts put out by LIGO as it detected the candidate gravitational waves from 2019. Lo and behold: the researchers discovered a “quasar flare” that appeared in the same sky region as the May black hole merger, but delayed by 35 days.

ESO/M. Kornmesser 

According to the researchers, the reason for the delay between the detection of the gravitational waves generated by the merger and the associated blast of light was due to the fact that the light was likely slowed as it scattered through the opaque accretion disk. Graham and his colleagues also say that their hypothetical model predicts that the resultant black hole from the merger was “kicked out” of the accretion disk, explaining the reason the flash of light from the quasar died down after 40 days.

Moving forward, the researchers hope to collect more evidence supporting the idea that the black hole merger did indeed occur within a quasar’s accretion disk. This evidence could be provided in less than two years, as the team predicts that the newly formed supermassive black hole—which, if it exists, is roughly 150 times more massive than the Sun—will come crashing back into the accretion disk in a little over one-and-a-half years.

If enough evidence confirms this supermassive black hole’s birth inside of a quasar, it would mean that black holes aren’t only born in darkness. In fact, it would mean that the most massive black hole ever observed was smashed into existence amidst a torrent of light.

What do you think about this potential evidence of light emitted by a black hole merger? Do you think Graham’s hypothesis will indeed prove to be valid? Let’s get some (civil) thought collisions going in the comments!

Feature image: Caltech/ R. Hurt