Feb 08, 2022 21:00:00

Succeeded in observing a 'stray black hole' 5150 light-years away using a 'gravitational lens'

Since black holes swallow even light, it is difficult to observe them directly with a telescope, etc., and observations using

phenomena characteristic of black holes such as gravitational waves and gamma-ray bursts are being attempted. Meanwhile, an overseas research team succeeded in observing a black hole located about 5150 light-years away from the earth using a phenomenon called ' gravitational lens '.

[2201.13296] An Isolated Stellar-Mass Black Hole Detected Through Astrometric Microlensing
https://arxiv.org/abs/2201.13296

Rogue black hole spotted on its own for the first time | Space
https://www.space.com/rogue-black-hole-isolated-discovery

It is said that there are hundreds of millions of 'stellar black holes' created by supernova explosions in the Milky Way galaxy to which the Earth belongs. Multiple stellar black holes have been observed so far, but they have been observed using interactions with celestial bodies such as neutron stars that exist in close proximity, and large-scale celestial bodies are observed around them. There was no case where an independent black hole that did not exist was observed. Therefore, the research team worked on the observation of an independent black hole.

The research team tried to observe a black hole by using a phenomenon called 'gravitational lens' in which a strong gravitational field such as a black hole bends light. Gravitational lenses are a phenomenon that causes not only black holes but also large-scale celestial bodies such as neutron stars and white dwarfs , and when you observe the point where the light is bent by the gravitational lens from the earth, it looks dark. According to Kailas Suff, a member of the research team, gravitational lenses with black holes affect the brightness of the surroundings over a long period of time. In addition, since black holes are invisible unlike other large-scale celestial bodies, if there is a 'point where the light is bent for a long period of time and the cause cannot be seen', the black hole exists there. You can think of it as.

The research team analyzed about six years of gravitational lens events detected by the Hubble Space Telescope. As a result, it was found that a gravitational lens event that met the above conditions occurred at a position about 5150 light-years away from the earth. The following image shows the observation result of the discovered gravitational lens event called 'MOA-2011-BLG-191 / OGLE-2011-BLG-0462', and the brightness of the star near the center changes depending on the observation date. You can see that it is doing.

The black hole discovered this time has about 7.1 times the mass of the sun and continues to move at 162,000 km / h. Researchers speculate that this black hole was created by the effects of a supernova explosion and continues to move at that momentum.

Based on the results of this research, Mr. Suff said that the Nancy Grace Roman Space Telescope and the latest telescope installed at the NSF Vera C. Rubin Observatory may be very useful for observing independent black holes in the future. It states that there is.