- The analysis has been accepted for publication in the Astrophysical Journal Letters.
- The mass of the compact object is closer to 7.1 solar masses.
For the first time, astronomers at the University of California, Berkeley, observed the brightening of a more distant star as its light was bent by the object’s powerful gravitational field — a phenomena known as gravitational microlensing. According to astronomers, the mass of the undetected compact object is estimated to be between 1.6 and 4.4 times that of the Sun.
They also caution that the object could be a neutron star rather than a black hole, because astronomers estimate that a relic of a dead star must weigh more than 2.2 solar masses to collapse into a black hole. Neutron stars are compact, dense objects. Internal neutron pressure, on the other hand, counteracts their gravity, preventing them from collapsing deeper into black holes.This was the first free-floating black hole or neutron star found with gravitational microlensing, according to Jessica Lu, an associate professor of astronomy at UC Berkeley.
Lu noted that they can investigate and weigh these little particles using microlensing, and believes that they have opened a new doorway into these dark objects that couldn’t be viewed in any other means.A graduate student, Casey Lam, was also involved in the study.The analysis has been accepted for publication in the Astrophysical Journal Letters.
The Space Telescope Science Institute (STScI) in Baltimore analysed the same microlensing event and claims that the compact object’s mass is closer to 7.1 solar masses, indicating that it is undoubtedly a black hole.While microlensing surveys detect roughly 2,000 stars per year, the combination of astrometric data allowed the two teams to establish the compact object’s mass and distance from Earth.
It is estimated to be between 2,280 and 6,260 light-years away, according to research led by UC Berkeley. It is 5,153 light-years away, according to the STScI group.After the STScI team first believed that five microlensing events recorded by Hubble — all of which lasted more than 100 days and thus could have been black holes — might not be created by compact objects after all, Lu and Lam became interested in the object in 2020.
Lam was shocked to find that one of the five microlensing events, OB110462, had compact object qualities when she investigated the photometry and astrometry. It did not appear to be a star because the lensing object was dark. The stellar brightness lasted about 300 days, and the location of the background star was shifted for the same period of time.
The length of the lensing session, according to Lam, was the most crucial aspect. In the year 2020, she discovered that the best way to find black hole micro lenses was to hunt for really long events. According to her, black holes account for only 1% of all measurable microlensing events, so looking at all of them would be like looking for a needle in a haystack. According to Lam, black holes account for roughly 40% of microlensing events lasting longer than 120 days.
According to Lu, OB110462’s gravitational influence on the light of the background star lasted an extremely long time. The star flashed brightly for about a year before peaking in 2011, then dimmed for a year before returning to normal.The velocity of the super compact lensing object was also calculated by both teams.
Lu and Lam discovered a speed of less than 30 kilometres per hour. The STScI researchers discovered a 45kilometerpersecond velocity, which they attributed to the alleged black hole receiving a boost from the supernova that created it.
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