EINSTEIN RING
1. Context
The European Space Agency’s (ESA) Euclid space telescope has discovered a rare ring of light, known as an Einstein ring, around a galaxy nearly 590 million light-years away from Earth.
2. What is the Einstein Ring?
- An Einstein ring appears as a luminous ring encircling a massive object such as dark matter, a galaxy, or a cluster of galaxies. It serves as a prominent example of gravitational lensing, a phenomenon where a massive celestial object creates a gravitational field that bends and magnifies the light from a more distant galaxy aligned behind it. According to NASA, the object responsible for bending the light is known as a gravitational lens.
- In the case of a recently identified Einstein ring, the galaxy NGC 6505 acted as the gravitational lens, distorting and intensifying the light from an unnamed galaxy situated 4.42 billion light-years away. Since one light-year equals 9.46 trillion kilometers, this means the light observed has traveled an immense distance.
- According to Xiaosheng Huang, a physics and astronomy professor at the University of San Francisco, gravitational lensing can produce various visual formations, with Einstein rings being the most striking.
- These rings are named after Albert Einstein, whose general theory of relativity predicted the bending and amplification of light by massive objects in space.
- The first Einstein ring was detected in 1987, and since then, astronomers have identified several others. However, they remain exceptionally rare, with estimates suggesting that fewer than 1% of galaxies exhibit this phenomenon.
- Due to their faint nature, Einstein rings cannot be seen with the naked eye and require advanced space telescopes, such as Euclid, for observation
3. Why do scientists study Einstein rings?
Einstein rings provide valuable insights into several key areas of astrophysics and cosmology. Scientists study them for the following reasons:
- Dark matter does not emit or reflect light, making it invisible. However, its gravitational effects can be observed through Einstein rings.
- By analyzing how light bends around galaxies, scientists can map the distribution of dark matter and estimate its quantity
- Einstein predicted that massive objects bend light due to gravity. Studying Einstein rings helps confirm and refine his theory of general relativity.
- Precise measurements of these rings provide real-world tests of gravitational lensing predictions
- The distance and redshift of the lensed galaxy help determine how fast the universe is expanding.
- By observing multiple Einstein rings at different distances, astronomers refine the Hubble constant, a key parameter in cosmology
- Some galaxies are too far away to be observed clearly, but gravitational lensing magnifies their light.
- This allows scientists to study early galaxies, star formation, and cosmic evolution in greater detail
- Einstein rings can also be used to detect planets around distant stars through a technique called gravitational microlensing
4. What is Einstein Cross?
An Einstein Cross is a rare phenomenon that occurs when a distant quasar (a highly energetic and luminous object) is gravitationally lensed by an intervening galaxy, creating multiple images of the quasar arranged in a cross shape around the galaxy. This effect is a special case of gravitational lensing and was first observed in the 1980s
The formation of an Einstein Cross requires the following conditions:
- A massive galaxy or cluster of galaxies acts as the gravitational lens.
- The quasi-stellar object (QSO), or quasar, lies directly behind the galaxy, and its light is bent by the gravitational field of the galaxy.
- The alignment of the lensing galaxy and the distant quasar is nearly perfect, which causes the light from the quasar to be split into four distinct images arranged in a cross shape
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For Prelims: Dark Sky Reserve, Indian Institute of Astrophysics, Indian Astronomical Observatory
For Mains:
1. Evaluate the socio-economic impact of astro-tourism on the Changthang region of Ladakh. How can a balance be achieved between promoting tourism and protecting the ecological and cultural heritage of the region? (250 words)
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Previous Year Questions
1. Consider the following phenomena: (UPSC CSE 2018)
Which of the above is/are the prediction/predictions of Albert Einstein’s General Theory of Relativity, often discussed in media? (a) 1 and 2 only Answer: (d) |
Source: Indianexpress
