![]() They named the distant galaxy “Spikey” for the spikes in brightness triggered by its suspected black holes magnifying each other on each full rotation via the lensing effect. ![]() Instead, Kepler ended up detecting the flares of what Haiman and his colleagues claim are a pair of merging black holes. NASA’s planet-hunting Kepler space telescope was scanning for the tiny dips in brightness corresponding to a planet passing in front of its host star. The researchers became interested in flaring supermassive black holes after spotting a suspected pair of supermassive black holes at the center of a far-off galaxy in the early universe. Physicists, therefore, have sought them out to test alternative theories of gravity in an effort to reconcile two competing ideas of how nature works: Einstein’s general relativity, which explains large scale phenomena like orbiting planets and the expanding universe, and quantum physics, which explains how tiny particles like electrons and photons can occupy multiple states at once. Einstein’s theory of gravity, known as general relativity, predicts the size of black holes. “That dark spot tells us about the size of the black hole, the shape of the space-time around it, and how matter falls into the black hole near its horizon,” said co-author Zoltan Haiman, a physics professor at Columbia.īlack hole shadows may also hold the secret to the true nature of gravity, one of the fundamental forces of our universe. The shadow of a black hole is both its most mysterious and informative feature. It should be possible to find this signal in many galaxies.” He added, “with our technique, you measure the brightness of the black holes over time, you don’t need to resolve each object spatially. “That approach only works for the biggest and closest black holes-the pair at the heart of M87 and potentially our own Milky Way.” ![]() “It took years and a massive effort by dozens of scientists to make that high-resolution image of the M87 black holes,” said the study’s first author, Jordy Davelaar, a postdoc at Columbia and the Flatiron Institute’s Center for Computational Astrophysics. If you measure how long the dip lasts, the researchers say, you can estimate the size and shape of the shadow cast by the black hole’s event horizon, the point of no exit, where nothing escapes, not even light. This subtle dimming can last from a few hours to a few days, depending on how massive the black holes, and how closely entwined their orbits. The lensing effect is well known, but what the researchers discovered here was a hidden signal: a distinctive dip in brightness corresponding to the “shadow” of the black hole in back. From this sideways vantage point, as one black hole passes in front of the other, you should be able to see a bright flash of light as the glowing ring of the black hole farther away is magnified by the black hole closest to you, a phenomenon known as gravitational lensing. Second, you need to be looking at the pair at a nearly side-on angle. First, you need a pair of supermassive black holes in the throes of merging. ![]() Outlined in complementary studies in Physical Review Letters and Physical Review D, their imaging technique could allow astronomers to study black holes smaller than M87’s, a monster with a mass of 6.5 billion suns, harbored in galaxies more distant than M87, which at 55 million light-years away, is still relatively close to our own Milky Way. Now, a pair of Columbia researchers have devised a potentially easier way of gazing into the abyss. ![]()
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