Scientists untangle mystery of the earliest galaxies 

Scientists untangle mystery of the earliest galaxies 

Subject : Science and Tech

Section: Space technology

Context:

Since beginning operations last year, the James Webb Space Telescope has provided an astonishing glimpse of the early history of our universe, spotting a collection of galaxies dating to the enigmatic epoch called cosmic dawn.

What is the James Webb Space Telescope (JWST)?

• It is a space telescope being jointly developed by NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA).
• It has taken 30 years and $10bn to develop, and is being described as one of the grand scientific endeavors of the 21st Century.

Where is it placed?

The James Webb Space Telescope will not be in orbit around the Earth, like the Hubble Space Telescope is – it will actually orbit the Sun, 1.5 million kilometres (1 million miles) away from the Earth at what is called the second Lagrange point or L2.

Untangling mystery of earliest galaxy

• The researchers used computer simulations to model how the earliest galaxies evolved, concluding that star formation may have unfolded differently in these galaxies in the first few hundred million years after the Big Bang event  13.8 billion years ago than it does in large galaxies populating the  cosmos today.
• Star formation in the early galaxies occurred in occasional big bursts, they found, rather than at a steady pace.
• So these galaxies may have been relatively small, as expected,  but might glow just as brightly as genuinely massive galaxies do, giving a deceptive impression of great mass.
• Astronomers can securely measure how bright those early galaxies are because photons (particles of light) are directly detectable and countable, whereas it is much more difficult to tell whether those galaxies are really big or massive. They appear to be big because they are observed to be bright.
• In contrast to forming stars at a nearly constant rate, the star formation activity in those early galaxies went on and off, on and off, with some large fluctuations over time.
• This, in turn, drives large variations in their brightness because the light seen  by telescopes like JWST was emitted by the young stars formed in those  galaxies.