Many small galaxies that existed early in the universe’s history are elongated in a surfboard-like shape, indicating the effect of a cosmic web of matter and constant merging with other small galaxies, deep observations using the James Webb Space Telescope have found.
New research using the James Webb Space Telescope (JWST) has found that dwarf galaxies in the early universe often appear flat, either “stretched” (stretched out along one axis) or very narrow, flattened ellipses shaped like a surfboard, while other galaxies have More flying saucer. Like the flattened appearance. These galactic dishes appear to grow more abundant as the Universe ages, as do compact, spherical galaxies.
“Approximately 50 to 80% of the galaxies we studied appear flat in two dimensions,” Viraj Pandya, an astronomer at Columbia University and lead author of a new paper describing the research, said in a press release. “[It]seems to be very common in the early universe, which is surprising because it’s not common nearby.”
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The discovery was made using data from CEERS, or Early Release Science of Cosmic Evolution, is a JWST program to uncover and explore the life of the oldest and faintest galaxies in the universe. It is an era extending from 600 million years after the Stone Age the great explosion To 6 billion years later, during which the galaxies that we see in the universe around us today formed, developed and matured, from spiral galaxies like the galaxy. milky way And the Andromeda Galaxyto giant ellipticals like M87.
CEERS builds on previous work by CEERS Hubble Space Telescope, which studied the early universe through deep-field images and the CANDELS (Cosmic Heritage Deep Extragalactic Near-Infrared Survey) program. Hubble found that massive galaxies in the early universe tended to take the shape of oblate spheroids, not unlike galaxies. Elliptical galaxies today. Less massive and therefore fainter galaxies were difficult for Hubble to detect, but from what he could see, many of them took on an elongated appearance made up of chains of brighter “blobs,” while other irregularly shaped dwarfs were called “froglets.” Fragments” or “blocks”.
The question was, given Hubble’s limitations, was it seeing a true reflection of the shapes of early small galaxies? The larger vision of JWST has now found that Hubble’s previous discoveries are correct.
Karthik Iyer, also of Columbia University, described how the greater visibility and sensitivity of JWST compared to Hubble is changing the study of galaxies in the early universe.
“Identifying additional classes of early galaxies is exciting, and there is a lot to analyze now,” Iyer said in the press release. “We can now study how the shapes of galaxies are related to what they look like and better show how they form in more detail.”
A picture of how galaxies evolve and grow over time now emerges.
Matter is distributed throughout the universe essentially in a cosmic web of threads that stretch across the universe. These threads mostly consist of: Dark matterWith a small fraction of ordinary matter mixed in those galaxies we observe. The abundance of expanding, surfboard-shaped galaxies can be explained by their formation within halos of dark matter stretched out in line with the strands of their cosmic web. Since other dwarf galaxies will also form within this string, mergers will occur along it, resulting in the growth of elongated galaxies that look like strings.
Over billions of years, the threads of the cosmic web disperse and grow more widespread. The merger rate slows and the fraction of expanding galaxies decreases as they begin to rotate and adopt an oblate, disk-like structure. These oblate galaxies are seen to increase by 20 to 60% over time and for a given galaxy mass.
Likewise, spherical galaxies are also growing more abundant over time, as compact star-forming galaxies settle into the universe to become the progenitors of the giant elliptical galaxies we see today, or spherical bulges of massive spiral galaxies.
Understanding the evolution of galaxies throughout cosmic history is a major goal of JWST. New findings from CEERS suggest that hierarchical mergers – the merging of smaller galaxies with larger galaxies, along the aforementioned cosmic strings – are key to understanding these diverse galaxy shapes.
The results are scheduled to appear in a paper to be published in a future issue of the Astrophysical Journal.