The first picture of a black hole – a fiery ring of light surrounding an empty black hole – stunned the world three years ago. The Event Horizon Telescope, a global network of synchronous radio disks that serve as a large telescope, brought into focus the black hole at the center of the galaxy Messier 87. Now, two Columbia University researchers have devised a more convenient method of looking into space. With this new development, astronomers can study black holes smaller than Messier 87 in more distant galaxies.
There are only two criteria for this approach. To begin with, there must be a pair of merging supermassive black holes. Second, this pair must be approached from an almost-face-to-face angle. From that point on, one can witness a bright flash as one black hole passes in front of the other. The bright ring of the more distant black hole is magnified by the black hole closest to the observer, a phenomenon known as gravitational lensing.
The lensing effect is well known, but the researchers discovered a hidden signal in this case: a marked decrease in brightness compared to the black hole’s shadow in the background. Depending on the enormous size of the black holes and how closely their orbits are linked, this slight dimming can last from a few hours to several days.
The study was published in the journal EASY physics review.
Jordy Davelaar, a postdoctoral fellow at Columbia and the Flatiron Institute’s Center for Computational Astrophysics, and first author of the study speak that high-resolution imaging of M87 black holes requires years and considerable effort by dozens of scientists. That method only applies to the largest and nearest black holes, such as the two at the center of M87 and possibly the Milky Way.
Davelaar added that their method involves measuring the luminosity of the black hole over time rather than resolving each object spatially.
Speaking of the black hole’s shadow, study co-author Zoltan Haiman said the size of the black hole, the pattern of space-time around it, and how matter falls into the black hole on its horizon are all revealed by the region. that night. Haiman is a professor of physics at Columbia.
After finding a pair of suspected supermassive black holes at the center of a distant galaxy in the early universe, researchers became interested in bursting supermassive black holes. NASA’s Kepler space telescope is looking for small dents that indicate a planet passing in front of its host star. Instead, Kepler detected flares from a pair of merging black holes, according to Haiman and his colleagues.
They named the distant galaxy “Spikey” because the spikes in brightness caused by its probable black holes amplify each other through a lensing effect on each rotation. Haiman and Davelaar then built a model to learn more about flares.
The researchers are now looking for more data from the telescope to confirm the drop in the Kepler data and prove that Spikey is indeed home to a pair of merging black holes. If all goes well, the method could be used to confirm some of the other suspected merging pairs of supermassive black holes out of the 150 or so that have been discovered so far.