Hidden ‘Goldilocks’ black hole exposed by early universe explosion

Published: 5th Apr, 2021

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.

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.

About

Key-highlights of the finding
Intermediate-mass black holes: The discovered black hole is Intermediate-mass black holes which is an elusive category of black holes that were considered non-existing until a few years ago.
- In 2020, the Hubble Space Telescopeprovided a piece of evidence for an IMBH.

Intermediate-mass black holes (IMBHs) are a class of a black hole with a mass approximately 100 to 100,000 times that of the Sun.

The technique used

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.

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. ?

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.

Blackhole and its subtypes

A black hole is a region of space-time where gravity is extremely strong that no object can escape from it.
Types: There are two types of black holes which become three with the discovery:
- Stellar-mass black holes: These are the black holes with a mass of fewer than 100 times that of the Sun.
- Supermassive black holes (SMBH): These are the ones with a mass greater than 100,000 times that of the Sun.

Both stellar black holes and SMBHs are commonly found.

Some of the discovered black holes

The first-ever black hole detected was Cygnus X-1 in 1964.
The closest black holeto Earth is a part of the system HR 6819 and is active just 1,000 light-years from earth
The smallest known black hole is GRO J0422+32. It was discovered in 1992 at around 7,800 light-years from us.
A supermassive black hole called Sgr A* and is 26,000 light-years from Earth. It holds a mass of at least 40 lakh times the Sun’s.

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