Albert Einstein was right: There is an area at the edge of black holes where matter can no longer stay in orbit and instead falls in, as predicted by his theory of gravity. <\/p>\n
Using telescopes capable of detecting X-rays, a team of astronomers has for the first time observed this area \u2014 called the \u201cplunging region\u201d \u2014 in a black hole about 10,000 light-years from Earth. \u201cWe\u2019ve been ignoring this region, because we didn\u2019t have the data,\u201d said research scientist Andrew Mummery, lead author of the study published Thursday in the journal Monthly Notices of the Royal Astronomical Society. \u201cBut now that we do, we couldn\u2019t explain it any other way.\u201d <\/p>\n
It\u2019s not the first time that black holes have helped confirm Einstein\u2019s grand theory, which is also known as general relativity. The first photo of a black hole, captured in 2019, had previously strengthened the revolutionary physicist\u2019s core assumption that gravity is just matter bending the space-time fabric. <\/p>\n
Many of Einstein\u2019s other predictions have turned out to be correct over the years, among them gravitational waves and the universal speed limit. \u201cHe\u2019s a tough man to bet against at this point,\u201d said Mummery, a Leverhulme-Peierls Fellow in the department of physics at the University of Oxford in the United Kingdom. <\/p>\n
\u201cWe went out searching for this one specifically \u2014 that was always the plan. We\u2019ve argued about whether we\u2019d ever be able to find it for a really long time,\u201d Mummery said. \u201cPeople said it would be impossible, so confirming it\u2019s there is really exciting.\u201d <\/p>\n
The observed black hole is in a system called MAXI J1820 + 070, which is made up of a star smaller than the sun and the black hole itself, estimated at 7 to 8 solar masses. The astronomers used NASA\u2019s space-based NuSTAR and NICER telescopes to collect data and understand how hot gas, called plasma, from the star gets sucked into the black hole. <\/p>\n
NuSTAR is short for the Nuclear Spectroscopic Telescope Array, which orbits Earth, and NICER, formally known as the Neutron star Interior Composition Explorer, is located on the International Space Station. <\/p>\n
\u201cAround these black holes there are big discs of orbiting material (from nearby stars),\u201d Mummery said. \u201cMost of it is stable, which means it can happily flow. It\u2019s like a river, whereas the plunging region is like the edge of a waterfall \u2014 all of your support is gone and you\u2019re just crashing headfirst. Most of what you can see is the river, but there\u2019s this tiny region at the very end, which is basically what we found,\u201d he added, noting that while the \u201criver\u201d had been widely observed, this is the first evidence of the \u201cwaterfall.\u201d <\/p>\n
Unlike the event horizon, which is closer to the center of the black hole and doesn\u2019t let anything escape, including light and radiation, in the \u201cplunging region\u201d light can still escape, but matter is doomed by the powerful gravitational pull, Mummery explained. <\/p>\n
The study\u2019s findings could help astronomers better understand the formation and evolution of black holes. \u201cWe can really learn about them by studying this region, because it\u2019s right at the edge, so it gives us the most information,\u201d Mummery said. <\/p>\n