Many black holes have been captured moving through the Milky Way.

Artist’s impression of a black hole in a cluster (ESA/Hubble N. Bartmann)
The fluffy constellations scattered across the sky might have secrets hidden in their hearts. That’s a swarm of more than 100 stellar-mass black holes.

If these findings can be verified It would explain how this star cluster formed. Its stars are light years apart. Scattered into a stream of stars that spanned 30,000 light years.

The cluster is called Palomar 5, about 80,000 light-years away. The ‘fossils’ of the early universe They are very dense and spherical. There are typically between 100,000 and 1 million old stars; Some, such as NGC 6397, are almost as old as the universe.

in any globular cluster All stars formed simultaneously from the same gas cloud. The Milky Way has about 150 globular clusters; These objects are excellent tools for studying, for example, the history of the universe. or the dark matter content of orbiting galaxies

But there is another type of constellation that is gaining more attention: tides. Streams of stars stretching across the sky. Previously, these were difficult to identify. But with the Gaia space observatory working to map the Milky Way with high precision in three dimensions. These streams are getting more exposure.

“We don’t know how these currents formed. But one idea is that they are scattered clusters,” explains Marc Giles, an astrophysicist at the University of Barcelona in Spain.

“however None of the newly discovered streams are associated with star clusters. So we’re not sure. We need to study the stellar systems associated with it. Palomar 5 is the only case that makes up the Rosetta Stone to understand the formation of the current and that is why we study it in detail.”

Palomar 5 is unique in that it is both widely distributed and loose stars. and tidal currents that stretch more than 20 degrees in the sky, so Gieles and his team live on it.

The team used detailed N-body simulations to reconstruct the orbits and evolution of individual stars in the cluster. to see how they will end up in the same spot

This is because recent evidence suggests that populations of black holes may exist in the central regions of globular clusters. And because the gravitational interactions with black holes are known to send stars out. Scientists therefore include black holes in some models.

Their results show that the large number of stellar-mass black holes within Palomar 5 could have contributed to the formation we see today. Interactions in orbit would pull stars out of the cluster and into tidal currents. But only with the number of black holes much higher than expected.

Stars escaping the cluster more efficiently and faster than black holes will cause the black hole’s proportions to change. causing the black hole to rise slightly

“The number of black holes was about three times the number of stars expected in the cluster. And this means that more than 20 percent of the entire cluster’s mass is made up of black holes,” said Giles.

“Each of them has about 20 solar masses. And they are formed by supernova explosions at the end of the lifespan of massive stars. when star clusters are very small.”

in billions of years The team’s simulations show that The star cluster will completely decay. before this happens What’s left of the cluster is entirely composed of black holes orbiting the center of the galaxy. This indicates that Palomar 5 is unique – it will dissolve completely into a stellar stream. Just like any other model we discovered.

It also indicates that other globular clusters Probably will have the same fate in the end. and proposed asserting that globular clusters might be excellent places to search for black holes that will eventually collide. Like a middleweight class black hole, the elusive between a star’s light mass and a supermassive one.

Fabio Antonini, an astrophysicist at Cardiff University in the UK, said: “It is believed that many mergers of binary black holes form in the cluster.”

“What is greatly unknown in this situation is the number of black holes present in the cluster. This is difficult to observe because we cannot see black holes. Our method allows us to learn how many black holes there are in a cluster by looking at the stars from which they eject.”

The research is published in Nature Astronomy.

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