Written by Dennis Overbye
Two astronauts recently went looking for a monster black hole. They would filter data from the most powerful telescopes on and above the Earth for any sign of an invisible object hundreds of times the mass of the sun in a distant cloud of stars called NGC 6397.
Instead, they found a nest of baby monsters, as many as five dozen: dark annihilation engines, packed into a space that was slightly larger than our own solar system, going back and forth and throwing the huge weight around in the dense heart of the browser star.
Eduardo Vitral and Gary A. Mamon of the Paris Institute of Astrophysics, using data from the Hubble Space Telescope and the European Space Agency’s Gaia spacecraft, reported their findings on Feb. 11 in the journal Astronomy and Astrophysics.
“We found very strong evidence for an invisible mass in the dense heart of the universe,” Vitral, a graduate student, said in a news release from the Space Telescope Science Institute. “But we were surprised to find that this extra mass is not like a point. ”
The amazing result has given astronauts a unique and detailed insight into the dynamics within one of the most crowded places in the nearby cosmos. Their work suggests that such source plates are similar to the gravitational waves detected by antennas such as LIGO and Virgo in recent years and which result from hitting black holes.
But the discovery raises questions about the forbidden and confusing process by which small black holes, just a few times the size of the sun, can come together and grow into behemoths that dominate galaxies’ centers. and that power quasars far away.
Black holes, as one would expect from Albert Einstein’s theory of common relations, are objects with such strong gravity that even light cannot escape them. There were doubts about its existence, but astronomers now agree that the universe is dotted with them, like a hole in space-time. Most of them are dead stars that fell on themselves and disappeared after burning up their thermonuclear fuel, with masses just a few times the sun.
But there are other black holes, with masses of millions or billions of suns, sitting in the centers of galaxies. There seems to be a correlation between the size of the galaxy and the mass of the black hole in its heart, but no one knows why or how such large holes are formed.
One idea is that these horrible black holes evolved from smaller, stellar-sized black holes, in which case there should be black holes of intermediate masses – worth hundreds or thousands of suns – going. around, perhaps in the hearts of smaller galaxies or galaxy fragments like NGC 6397. But so far these intermediate black holes are missing in action.
The NGC 6397 collection is one of about 150 spherical clouds of old stars that orbit the Milky Way and possibly pre-formed. It is 13 billion years old and has around 250,000 stars, all old and small. Long ago the brightest, heaviest stars in the cluster burned through their lives and met their fate as black holes or other products of stellar decline.
So the browser seems to be a candidate to port a massive black hole. In fact, earlier studies had suggested that there would be a black hole of about 600 masses of sun anchor in the middle of NGC 6397.
To explore that idea, Mamon and his student turned to very high opinions about the movements of individual stars in the group, which acquired the Hubble Space and Gaia Telescope. The faster the stars move, the more the gravitational force, and therefore the more mass, needs to be present to keep them in the cluster.
In total, 1,905 stars from the Gaia catalog and 7,209 stars from Hubble were evaluated. As it turned out, they were in fact under the influence of invisible mass gravity. But instead of tightly circling one dark point, the stars moved all the way, suggesting that whatever dark mass was affecting them was focused only on the expansion. There was no sign of a gargantuan black hole.
“Our analysis showed that the orbits of the stars are almost random across the globe, rather than being systematic or very long,” Mamon said in an email.
The motions of these stars offered evidence of a dark mass equivalent to 1,800 suns spread across an area – a cloud within the cloud – about a third of a light year. Sharing that space are about 40,000 normal, light but very light stars. According to models of stellar evolution, Mamon said, about two-thirds of this dark material would be black holes, with an average mass of 20 suns. The rest of the dark matter would be left over from dead stars, such as white dwarfs or neutron stars.
It is unclear what will happen now, the astronauts said. Random unions between the black holes could cause them to lose mass in the form of gravity waves. This integration could also lead to black holes in the cluster. And gravitational interactions with smaller stars in the cluster may cause them to lose speed and sink to the center of the cluster, in a process known as “dynamic counter-rotation.”
“This could bring the black holes to the center in a few million years, where they will meet in a massive black hole,” said Mamon.
But that time window is nothing compared to the 13 billion years that the browser has been in, Mamon noted, so it would be “lucky,” at least to say, if astronauts had focusing on the cluster at this very moment a brief action took place. With no central black hole now, it looks like no one may ever exist. The sinking of the black holes towards the center may stop as the black holes come across too few stars to exchange energy, and “this would stop the creation of IMBH,” he said.
Vitral said, “We’re definitely coming up with a lot of ideas for creating intermediate black holes!” When we found this invisible collection in a heart-breaking world. ”