Double Quasars - A Rare Discovery in the Universe | UPSC Notes

Understanding Quasars

Image source: skyandtelescope.org

Known as "quasi-stellar objects," quasars are incredibly luminous and distant celestial bodies that emit massive amounts of energy. They are among the most radiant objects in the universe, visible even billions of light-years away. Here are a few key points about quasars:

• They are powered by supermassive black holes present at the centres of galaxies, which ingest gas and dust from their surroundings.
• As the material is pulled towards the black hole, it heats up and emits intense radiation, creating the bright glow characteristic of a quasar.

The Advent of Close Binary Quasars Research

In recent years, scientists have begun to study close binary quasars. Here are some key findings:

• Modern observatories have the power to spot instances where two quasars are simultaneously active and are predicted to merge eventually.
• Research indicates that large galaxies are formed as a result of smaller ones merging together.
• As these galaxies merge, supermassive black holes are likely to be formed in the resulting entity.

Why is the Discovery of Binary Quasars Significant?

The discovery of two closely bound quasars is a breakthrough in astrophysics for several reasons:

• It suggests the possibility of more such pairs existing in the early universe.
• It can assist researchers in understanding the formation and frequency of black hole mergers.
• It provides scientists with a method to identify these closely bound binary quasars.
• It can potentially enhance our understanding of the evolution of the universe.

The Hunt for Binary Quasars

The search for binary quasars involved the use of advanced technology from different observatories. Here's how it was done:

• NASA’s Hubble Space Telescope and W.M. Keck Observatories in Hawaii were used to locate the quasars.
• The International Gemini Observatory in Hawaii, NSF’s Karl G. Jansky Very Large Array in New Mexico, and NASA’s Chandra X-ray Observatory contributed to the study.
• ESA’s Gaia space observatory played a crucial role in identifying the double quasar.

How Gaia Helped in Identifying Binary Quasars

Scientists devised a new technique using the Gaia space observatory to identify potential double-quasar candidates. Here's how:

• Gaia is adept at measuring the positions, distances, and motions of nearby objects. However, researchers found a way to use Gaia’s database to explore the distant universe.
• They searched for quasars that appeared as single objects in the data due to their close proximity.
• Gaia was able to detect a small, unexpected “jiggle” that suggested some of the quasars were moving.

Challenges in Identifying Binary Quasars

The identification of binary quasars is not without its challenges:

• A nearby galaxy could make a faraway quasar appear as two objects, giving a false impression of a binary pair.
• The Keck telescope was used to confirm that there were no galaxies between the suspected double quasar and us.
• Gravity can distort space, which can also create the illusion of a binary pair.

Conclusion

The discovery of binary quasars in the early universe is a significant milestone in our understanding of the universe. The upcoming NASA’s Nancy Grace Roman Space Telescope is expected to further advance this area of research, enabling researchers to identify more binary quasars.

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