Australian scientists have discovered a particularly rare medium-mass black hole in the early universe due to the gravitational lensing effect.
Over 10.7 billion years ago, when the universe was 3 billion years old, a gamma ray explosion known as GRB 950830 in the far galaxy lit up deep space. In 1995, astronomers observed this event, essentially “going back in time” with the high-energy astrophysics experiment BATSE at the Compton Gamma-Ray Observatory, launched in 1991 on the space shuttle Atlantis.
In a new study published in the journal Nature Astronomy on March 29, astrophysicists at the Australian University of Melbourne, led by James Paynter, used light from this ancient explosion to detect a medium mass black hole (IMBH), estimated at 10,000 times heavier. than the sun.
ImbH is also known as an intermediate black hole because it has a mass between a stellar mass black hole (SBH) and a supermassive black hole (SMBH). While SBH (which is 5 to 10 times heavier than the Sun) and SMBH (which weighs millions to billions of Suns) are so ubiquitous in space, IMBH is so difficult to detect that some scientists must be wondering: “Do they really exist?”
The light emitted by the gamma-ray burst allowed the team to use the phenomenon of the gravitational lens to find IMBH. The new discovery not only proves the existence of IMBH, but also reveals why SMBH can reach such large volumes.
Gravitational lenses are phenomena that occur when an object (like a black hole) behaves like a lens, distorting incoming light from a distant source (like a gamma-ray burst). This distortion signals to astronomers that a large object must be in the way.
To determine what type of object causes the gravitational lens, the team went further by determining its mass. Since the object’s mass is within range of an IMBH, they decide it’s probably possible. Paynter and his colleagues added that they ruled out the possibility that the objects were globular clusters or a halo of dark matter because they weren’t small and dense enough to create a gravitational lensing effect.
Although the new discovery is a major step in proving the existence of IMBH, there are still many mysteries to be discovered about this type of black hole. Scientists still do not fully understand their origin.
Many theories have been put forward, including that IMBH could form from the fusion and collapse of supermassive hydrogen stars, or develop from the first stellar-mass black holes. If SBH can gradually increase its volume to become real estate, IMBH can also become SMBH, the team pointed out.
