Albert Einstein was right: there is an area on the edge of the black holes where matter can no longer remain in orbit and instead falls, as predicted by his theory of gravity.
Using telescopes capable of detecting X-rays, a team of astronomers observed this area — called “diving region” — in a black hole about 10,000 light years from Earth. “We’ve been ignoring this region because we didn’t have the data,” said research scientist Andrew Mummery, lead author of the study published Thursday in magazine Monthly Notices of the Royal Astronomical Society. “But now that we have [os dados]we couldn’t explain it any other way.”
It’s not the first time that black holes have helped confirm Einstein’s great theory, which is known as general relativity. The first photo of a black hole, captured in 2019, had already strengthened the revolutionary physicist’s central assumption that gravity is just matter curving the fabric of space-time.
Many of Einstein’s other predictions have proven correct over the years, including gravitational waves and the universal speed limit. “He’s a difficult man to bet against at this point,” said Mummery, of the physics department at the University of Oxford in the United Kingdom.
“We went looking for this [evidência] specifically — that was always the plan. We discussed for a long time whether we would ever be able to find her,” Mummery said. “People said it would be impossible, so confirming it’s there is really exciting.”
“Like the edge of a waterfall”
The observed black hole is in a system called MAXI J1820 + 070, which is composed of a star smaller than the sun and the black hole itself, estimated at 7 to 8 solar masses. Astronomers used NASA’s NuSTAR and Nicer space telescopes to collect data and understand how hot gas, called plasma, from the star is sucked into the black hole.
NuSTAR is the acronym for Nuclear Spectroscopic Telescope Array, which orbits the Earth, and Nicer, formally known as the Neutron star Interior Composition Explorer, is located on the International Space Station.
“Surrounding these black holes are large disks of orbiting material (from nearby stars),” Mummery said. “Most of it is stable, meaning it can flow smoothly. It’s like a river, while the diving area is like the edge of a waterfall — all your support disappears and you’re just falling head first. Most of what you can see is the river, but there’s this little region at the end, which is basically what we found,” he added, noting that while the “river” has been widely observed, this is the first evidence of the “waterfall.” .”
Different from event horizonwhich is closest to the center of the black hole and does not allow anything to escape, including light and radiation, in the “dip region” light can still escape, but matter is doomed by the powerful gravitational pull, Mummery explained.
The study’s findings could help astronomers better understand the formation and evolution of black holes. “We can really learn about them by studying this region, because it’s right on the edge, so it gives us the most information,” Mummery said.
Something missing from the study is a real image of the black hole, as it is very small and distant. But another team of Oxford researchers is working on something even better than a photo: the first movie of a black hole. To achieve this, the team will first need to build a new observatory, the Africa Millimeter Telescope in Namibia, which Mummery hopes will be operating within a decade. The telescope, which will join the international Event Horizon Telescope collaboration that captured the groundbreaking black hole image in 2019, will allow scientists to observe and film large black holes at the center of the Milky Way and beyond.
A link to the past
According to Christopher Reynolds, professor of astronomy at the University of Maryland, College Park, finding real evidence of the “dipping region” is an important step that will allow scientists to significantly refine models of how matter behaves around a black hole. “For example, it could be used to measure the rotation rate of the black hole,” said Reynolds, who was not involved in the study.
Dan Wilkins, a research scientist at Stanford University in California, calls this an exciting development and points out that in 2018, there was an extremely bright burst of light from one of the black holes inside our galaxy, accompanied by an excess of X-rays. high energy.
“At the time, we hypothesized that this excess was from hot material in the ‘dip region,’ but we didn’t have a complete theoretical prediction of what this emission would look like,” said Wilkins, who also was not involved in the new study.
This study actually performs that calculation, he added, using Einstein’s theory of gravity to predict what X-rays emitted by material in the “dip region” around a black hole would look like, and compare that to data from that bright explosion in 2018.
“This will be a prime space of discovery for the next decade or so,” said Wilkins, “as we await the next generation of X-ray telescopes that will give us more detailed measurements of the innermost regions just outside the event horizons of black holes. ”
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