A black hole has been discovered via gravitational microlensing, being one of 200 million within the galaxy.
A black hole is formed when huge stars reach the endpoint of their life and burst into a supernova. One out of every thousand stars is thought to be large enough to create a black hole. With an approximated 100 to 400 billion stars in the Milky Way, there are probably a large number of black holes scattered around our galaxy.
Black holes, on the other hand, are notoriously harder to identify, specifically if they are solitary. Because a black hole’s gravity is so strong that light cannot escape, we usually identify holes by their gravitational pull on other bodies or by the radiation produced by the stuff it is eating. There might be millions of black holes around our galaxy that are completely undetectable to scientists due to the absence of surrounding objects or accreting material.
If big stars die and leave behind black holes, as scientists believe, there must be millions of them distributed all across the Milky Way galaxy. The issue is that confined black holes are undetectable.
Now, a team led by astronomers from the University of California, Berkeley, has discovered what appears to be a free-floating black hole by noticing the illumination of a much more celestial object as its brightness was altered by the object’s strong gravity pull — a process known as gravitational microlensing.
The team, directed by UC Berkeley assistant professor of astronomy Jessica Lu and graduate student Casey Lam, calculates that the mass of the undetectable compact object is somewhere between 1.6 & 4.4 times that of the sun. The UC Berkeley scientists caution that the material could be a neutron star rather than a black hole since experts believe the relic of a dead star has to be more massive than 2.2 solar masses, in addition, to falling into a black hole. Neutron stars are however tight, compact bodies, but their gravitation is counterbalanced by inner neutron pressures, which prohibits them from collapsing further into black holes.
‘ It is the first gravitational microlensing discovery of a neutron star or free-floating black hole,’ Lu stated. ‘ We can investigate these solitary, compact bodies with microlensing and measure them.’ I believe we’ve uncovered a new window into these black objects that couldn’t be viewed in any other manner.’
