The stellar “ghost”: Scientists believe that they have discovered the first floating black hole
A team of astronomers led by the University of California, Berkeley, has discovered what could be a floating black hole for the first time, by observing the brightness of a farther star as its light is distorted by an object's strong gravitational field - the so-called microgravity.
The team, led by graduate student Casey Lamm and UC Berkeley professor of astronomy, Jessica Lu, estimates that the compact, invisible object has between 1.6 and 4.4 times the mass of the Sun.
Since astronomers believe that the remnant of a dead star must be heavier than 2.2 solar masses to become a black hole, the University of California researchers warn that the detected object could be a neutron star rather than a black hole. Neutron stars are also very dense and compact objects, but their gravity is balanced by internal neutron pressure, which prevents them from turning into a black hole.
But whether it's a black hole or a neutron star, the object is the first dark stellar remnant or stellar ghost, discovered wandering through our galaxy unassociated with another star.
"This is the first floating black hole or neutron star to be detected by microgravitational lenses," Lu said.
"By using the finer lens, we can examine these solitary, compressed objects. I think we have opened a new window on these dark objects, which cannot be seen any other way," she said.
Returning to the news, it is worth noting that a competing team from the Space Telescope Science Institute (STScI) in Baltimore analyzed the same micro-lensing event and claimed that the mass of the compact object is closer to 7.1 solar masses and that the detected object is an undisputed black hole. The team is also published in The Astrophysical Journal.
The UCSD researchers suspect that the two teams' different conclusions are due to the fact that the astronomical and photometric data give different measures of the relative motions of the fore and aft objects. Astronomical analysis also differs between the two teams, and the UCSD team argues that it is not yet possible to distinguish whether the object is a black hole or a neutron star.
"As much as we would definitively say it's a black hole, we should report all permissible solutions," Lu said. "This includes both black holes of lower mass and maybe even a neutron star."
Scientists hope to resolve this discrepancy in the future with more Hubble data and improved analysis.
Since our Milky Way is home to an estimated 100 to 400 billion stars, there must be hundreds of millions of black holes scattered throughout the galaxy, as they form as a result of the explosion of massive stars when they reach the end of their lives, however, it can be difficult Very unobtrusive as they are often invisible.
But astronomers search for it by its strong gravitational influence, which does not escape light, or by radiation from the surrounding matter that devoured it. We may have discovered the first floating black hole.
The team's analysis has been accepted for publication in The Astrophysical Journal Letters, with the team finding that the possible number of black holes in the galaxy is 200 million.
Determining how many of these compact objects inhabit the Milky Way will help astronomers understand the evolution of stars and understand our galaxy.
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