Astrophysicists at the University of Waterloo have discovered the most distant jellyfish galaxy ever observed, offering a glimpse into how galaxies formed and evolved more than 8 billion years ago.
Since the launch of the James Webb Space Telescope (JWST), ongoing discoveries by astronomers have driven a steady wave of insights that have fundamentally reshaped our understanding of how the universe developed.
Jellyfish galaxies, as their name implies, are characterized by long, tentacle-like streams of gas and newly formed stars trailing behind them. These features are created by hot, dense galaxy clusters surrounded by gas, which acts like a powerful wind, stripping away the galaxy’s own gas in a process known as ram-pressure stripping.
“We were looking through a large amount of data from this well-studied region in the sky with the hopes of spotting jellyfish galaxies that haven’t been studied before,” said Dr. Ian Roberts, Banting Postdoctoral Fellow at the Waterloo Centre for Astrophysics in the Faculty of Science. “Early on in our search of the JWST data, we spotted a distant, undocumented jellyfish galaxy that sparked immediate interest.”
Peering Into the Ancient Universe
This newly discovered galaxy has a redshift of z = 1.156, meaning astronomers are seeing it as it existed approximately 8.5 billion years ago, well before the genesis of our own planet. This makes it the earliest known example of a jellyfish galaxy, providing important evidence that harsh environmental processes were already shaping galaxies at that time.
The research team uncovered the galaxy while analyzing deep-space observations from the COSMOS field, also known as the Cosmic Evolution Survey. This carefully selected region of the sky has been studied extensively by multiple observatories because it offers a clear view into the distant universe.
From its position at such a great distance from the Milky Way, the field has little interference from nearby stars and dust. It is also visible from both hemispheres, and free of bright foreground objects, making it ideal for studying faint, distant galaxies.
“The first is that cluster environments were already harsh enough to strip galaxies, and the second is that galaxy clusters may strongly alter galaxy properties earlier than expected,” Roberts said. “Another is that all the challenges listed might have played a part in building the large population of dead galaxies we see in galaxy clusters today.”
“This data provides us with rare insight into how galaxies were transformed in the early universe,” Roberts added.
More Challenges to Past Astrophysical Data
The discovery challenges previous models of cosmic evolution, as until now, scientists believed that 8.5 billion years ago, galaxy clusters were still assembling and that ram-pressure stripping would have been relatively uncommon.
By contrast, recent discoveries from Webb indicate that cluster environments were already dense and turbulent enough to dramatically reshape galaxies.
As the James Webb Space Telescope continues to peer deeper into the cosmos, more discoveries like this are inevitable, with each new finding expanding our knowledge of the universe and upending many past assumptions about galaxies and other celestial features within it.
The paper, JWST Reveals a Candidate Jellyfish Galaxy at z=1.156, can be found in The Astrophysical Journal.
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