First black hole picture5/8/2023 ![]() ![]() “Anything that you were just barely struggling to detect before, you get really solid detections now.” ![]() “ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories. Among the newcomers was the Atacama Large Millimeter/submillimeter Array, or ALMA, located on a high plateau in northern Chile. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Over time, the EHT recruited new radio observatories. But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself. In 2009, a network of just four observatories - in Arizona, California and Hawaii - got the first good look at the base of one of the plasma jets spewing from the center of M87’s black hole ( SN: 11/3/12, p. The EHT was not always the hotshot array that it is today, though. For the EHT in 2017, that was the distance from the South Pole to Spain. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. Instead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. ![]() The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.”Ĭreating that first-ever portrait of a black hole was tricky, though. “There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the first image of a supermassive black hole, the one inside the galaxy M87. Telescopes can look instead for the silhouette of a black hole’s event horizon - the perimeter inside which nothing can be seen or escape - against its accretion disk. Luckily, there’s a way to “see” a black hole without peering into the abyss itself. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. ![]() Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. That's bad news, because Myoshi thinks the alleged error could affect the way other black hole images turn out - including, provocatively, the new EHT image of the black hole at the center of our own Milky Way galaxy released this month.Black holes are extremely camera shy. National Astronomical Observatory of Japan researcher Makato Myoshi and colleagues used a wider field of view to get the new image of M87*, which cut out the ring of light around the donut-shaped structure that appeared in the 2019 image. As with any algorithm, though, that unfortunately means there's room for human error and incorrect assumptions - and that's an issue here, because the new image doesn't look like the one from 2019. Like the original team, they used an algorithm to fill in the blanks and compile the vast heap of data into a single image. New Scientist reported this week that the group used the same data from the Event Horizon Telescope (EHT), a collection of eight radio telescopes that act as one, to produce a new version of the iconic black hole image released in 2019. It took researchers in Japan three years to produce an image of M87*, the black hole in the center of the M87 galaxy. Sorta TwinningĪ new image of a black hole in the center of a distant galaxy just dropped, but it's making researchers worried that the first image of the same one wasn't quite right. The last image was a "mistake," they say. ![]()
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