Megamaser: cosmic light show in the universe
What is a megamaser?
A megamaser is a naturally occurring astronomical source that amplifies microwave or radio radiation, similar to how a laser amplifies visible light.
MASER stands for Microwave Amplification by Stimulated Emission of Radiation.
When such emission is millions of times brighter than typical masers, it is called a megamaser.
They are usually observed in distant galaxies experiencing intense activity.
A recent observation using the MeerKAT radio telescope detected the most distant hydroxyl megamaser known so far.
What is a hydroxyl megamaser?
A hydroxyl megamaser is a giant and naturally occurring laser found in deep space.A hydroxyl megamaser forms when radiation interacts with hydroxyl (OH) molecules in space.
Hydroxyl molecule
Composed of one oxygen atom and one hydrogen atom (OH).
Found in dense molecular gas clouds inside galaxies.
Formation process
Galaxy collisions or mergers occur.
This triggers intense star formation (starburst) and feeds supermassive black holes.
Large amounts of infrared radiation are released.
Infrared energy excites hydroxyl molecules into high-energy states.
When molecules return to lower energy levels, they emit amplified radio waves → forming a megamaser.
Example in news
One known megamaser source is the galaxy IRAS 16399-0937, located about 370 million light-years from Earth.
Recently discovered megamaser emissions from galaxies billions of light-years away were magnified by gravitational lensing, making them exceptionally bright. Such extremely luminous events are sometimes referred to as “gigamasers.”
Scientific importance
Megamasers act as cosmic beacons for astronomers.
They help scientists to:
Study galaxy mergers and starburst activity.
Observe regions hidden by cosmic dust, since radio waves penetrate dust clouds.
Measure galaxy rotation and velocities.
Improve estimates of cosmic distances and expansion of the universe.
Understand the evolution of galaxies and supermassive black holes.
Prelims Practice MCQs
Q. Consider the following statements regarding masers and megamasers:
Maser stands for Microwave Amplification by Stimulated Emission of Radiation.
Megamasers are naturally occurring astronomical sources that emit extremely intense radio waves.
Hydroxyl megamasers are associated with galaxy mergers and intense star formation.
Which of the statements given above are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Answer: D
Explanation:
Maser refers to microwave amplification by stimulated emission → Statement 1 correct.
Megamasers are powerful cosmic masers emitting strong radio waves → Statement 2 correct.
Hydroxyl megamasers are typically found in merging galaxies with starburst activity → Statement 3 correct.
Q. Hydroxyl megamasers observed in distant galaxies are primarily detected using:
A. Optical telescopes observing visible light
B. Radio telescopes detecting microwave emissions
C. X-ray telescopes observing black hole radiation
D. Infrared telescopes detecting cosmic dust
Answer: B
Explanation:
Megamasers emit microwave/radio wavelengths, so they are detected using radio telescopes such as the MeerKAT array.