IUCAA: Scientists from Pune present ground-breaking discovery on the Dark Age of the Universe | News from Pune

PUNE: Pune Scientists IUCAA they said they have found clues to how light first entered a cosmic fog billions of years ago, allowing the universe to wake up from its “dark ages“.

After the Big Bang, the universe was filled with a thick fog of hydrogen gas that blocked ultraviolet light (emitted by the first stars) from traveling freely. Scientists call this period the “cosmic dark ages”.
Over time, this dark universe became transparent, allowing light to travel great distances. Researchers at the Interuniversity Center for Astronomy and Astrophysics (IUCAA) said they have found a clue that could help explain this cosmic makeover. Using powerful telescopes, they observed two massive galaxies merging about 8 billion light-years away.
“These galaxies were found to emit a rare type of ultraviolet light, known as Lyman-continuum radiationwhich can remove electrons from hydrogen atoms. This process could have cleared the haze and transformed the universe from a dark, opaque state to the transparent, star-studded cosmos we see today,” IUCAA astrophysicist Kanak Saha told TOI.
Scientists have long wondered what provided enough light to clear the haze of the early universe. IUCAA researcher Soumil Maulick said: “We can’t directly observe the early universe, and when it went from dark and opaque to bright and visible. So we look at galaxies in the nearby universe to understand what kind of galaxies could have been responsible for this process.”
Maulick said the discovery suggests that when galaxies collide, they could release a lot of this special radiation. “Such galaxy collisions were much more common in the early universe. If they all leaked light like this, they could have played an important role in illuminating the cosmos,” he said.
The study found that the amount of light (Lyman-continuum or LyC photons) escaping from the galaxy system is consistent with what is needed to complete reionization, a process that made the early universe transparent and it was dark and opaque.
Saha said: “Mergers between galaxies are known to trigger bursts of star formation. This could be contributing to increased production of ionizing photons (which can strip electrons from hydrogen and allow light to travel freely). The interaction of galaxies through mergers is likely to play an important role in this. We found that light from AF13753, the galaxy we studied, probably escapes through narrow, dust-free channels. which makes it harder to detect by specific paths.”
Maulick added: “AF13753 does not fit the usual profile of galaxies that filter this type of radiation. Despite this, it still has a significant fraction of the light escaping, suggesting that merging systems like these could to have played an important role in the creation of the universe. transparent after the cosmic dark ages.”
Scientists used powerful telescopes including the Hubble Space Telescope (HST), the James Webb Space Telescope (JWST) and AstroSat’s Ultraviolet Imaging Telescope (UVIT) to detect the special light escaping from the colliding galaxies 8 billion light years away. This study was recently published in ‘The Astrophysical Journal’, an international journal.
“Scientists were able to see something that happened billions of years ago because light, although incredibly fast, takes time to travel the vast distances of space. The light we see today was emitted long ago billions of years and it’s only just reached us.” Maulick said.