Hidden ‘Goldilocks’ black hole exposed by early universe explosion

Context:

Analysis of light of a gamma-ray burst, which dates back three billion years ago, has revealed the presence of a previously undetected black hole.

What is a gamma-ray burst?

• The gamma-ray burst that is known as GRB 950830 was detected in 1995.
  • GRBs are the most energetic form of electromagnetic events in the universe having short bursts of gamma rays that ejected at the speed of light.
• Gamma-ray bursts are formed when a high-mass star collapses and creates a neutron star or black hole.
• The gravitational lensing technique was used to detect the black hole.
  • Under this technique, the gravity around a massive body bends light that comes from a source behind.
  • It is then used to identify the intermediate-mass black hole (IMBH) which lensed the gamma-ray burst.

About the finding

Intermediate-mass black holes: The discovered black hole is an Intermediate-mass black hole which is an elusive category of black holes that was considered non-existing until a few years ago.

• In 2020, the Hubble Space Telescope provided a piece of evidence for an IMBH.

Intermediate-mass black holes (IMBHs)

These are a class of black holes with a mass approximately 100 to 100,000 times that of the Sun.

What is Gravitational lensing?

• When the light from distant galaxies or events like gamma-ray bursts passes by massive objects in the universe such as stars or black holes then Gravitational lensing is expected to occur.
• The gravitational tug of these massive bodies can bend the light and causes the source to look distorted.
  • Weak: When gravitational lensing is weak, it distorts the distant object or galaxy to appear magnified or stretched out.
  • Strong: When it is strong, it bends light to such a degree that multiple images of the same galaxy are visible.