First Direct Observation of a Smaller Black Hole in a Pair

OBSERVATION OF A SMALLER BLACK HOLE IN A PAIR

Source: PIB

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Context

An international study involving 32 scientists from 10 countries (Finland, Poland, India, China, USA, Czech Republic, Japan, Germany, Spain, and Italy) has successfully observed a smaller black hole orbiting a larger one in the distant galaxy OJ 287.
This discovery marks the first direct observation of such an event.

Details

Background

Galaxy OJ 287: Located 4 billion light years away, this galaxy has been the subject of study for its unique black hole pair.
Initial Theory: The presence of two black holes was first proposed by astronomers at the University of Turku, Finland.
NASA's TESS: In 2021, NASA's Transiting Exoplanet Survey Satellite (TESS), typically used for discovering exoplanets, was pointed towards OJ 287 to help confirm the black hole pair theory.

Key Findings

Indirect Evidence: Previous studies suggested a massive black hole orbiting a giant black hole 100 times its size.
Direct Observation: TESS monitored the brightness of the primary black hole and its jet, detecting a flare that indicated the smaller black hole’s presence.
Accretion Disk Interaction: The flare occurred when the smaller black hole interacted with the accretion disk of the larger black hole, producing a bright jet of gas.
Color Change: The jet’s brightness caused a temporary change in OJ 287’s color from red to yellow.
Future Prospects: The smaller black hole is expected to emit nano-Hertz gravitational waves, detectable by pulsar timing arrays in the near future.

Key Information About Galaxies

*Attribute*	*Details*
Definition	A galaxy is a massive system of stars, stellar remnants, interstellar gas, dust, dark matter, and more, bound together by gravity.
Formation	Galaxies formed approximately 1 billion years after the Big Bang through the gravitational collapse of gas and dark matter. They continue to evolve through interactions and mergers.
Types of Galaxies	1. Spiral Galaxies: Characterized by flat, rotating disks with central bulges and spiral arms (e.g., Milky Way). 2. Elliptical Galaxies: Oval-shaped, containing older stars and less interstellar matter. 3. Irregular Galaxies: Lack a distinct shape, often due to gravitational interactions. 4. Lenticular Galaxies: Hybrid between spiral and elliptical.
Size and Scale	- Largest Galaxies: Contain trillions of stars, spanning up to a million light-years across. - Smallest Galaxies: Contain a few thousand stars, spanning just a few hundred light-years.
Components	- Stars: Ranging from millions to trillions. - Interstellar Medium: Gas and dust clouds. - Dark Matter: Constitutes most of the mass, affecting the rotation and structure. - Supermassive Black Holes: Often found at the centers of galaxies.
Age	Most galaxies are between 10 billion and 13.6 billion years old. Some are nearly as old as the universe itself, which is about 13.8 billion years old. The youngest known galaxy formed roughly 500 million years ago.
Structures	- Groups: Contain up to 100 galaxies. - Clusters: Contain thousands of galaxies. - Superclusters: Massive conglomerations of clusters, not gravitationally bound. - Cosmic Web: Large-scale structure of the universe, consisting of voids, walls, and filaments.
Examples	- Milky Way: A spiral galaxy with a disk spanning over 100,000 light-years. - Andromeda Galaxy: A nearby spiral galaxy on a collision course with the Milky Way. - Messier 87 (M87): An elliptical galaxy with a supermassive black hole at its center.

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Sources:

PIB

PRACTICE QUESTION

Q: With reference to black holes, consider the following statements:

The event horizon of a black hole is the boundary beyond which nothing can escape, not even light.
Hawking radiation is a theoretical prediction that black holes can emit radiation due to quantum effects near the event horizon.
The size of the event horizon is directly proportional to the mass of the black hole.

Which of the statements given above is/are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(d) 1, 2, and 3

Answer: (d)