When the James Webb Space Telescope lifted off from Earth on Christmas Day in 2021, it carried a lot of expectations with it. One of its scientific goals is to seek the light from the first galaxies in the Universe and to study how galaxies form and evolve. A new paper shows that the JWST … Continue reading 'The James Webb Links Modern Green Pea Galaxies to Ancient Galaxies in the Cosmic Dawn'
The evidence for the EOR is buried in the deep, distant past. The light from those early galaxies has been stretched to extreme redshifts by the expansion of the universe since then, and the JWST was meticulously designed to detect that infrared light. It has succeeded, and early in its scientific mission, the JWST has already detected the oldest galaxies ever found, dating to only 350 million years after the Big Bang.
But Green Peas are also green because they host very active star formation. Unlike stars, which emit light across the electromagnetic spectrum, the light from green peas comes from clouds of glowing gas lit up by starlight. So instead of seeing the unfiltered starlight, we see only the light from the energized gas clouds.
Green Peas are only about 5,000 light-years across. Compare that to most modern galaxies like the Milky Way, about 85,000 light-years across. Green Pea galaxies are clearly odd, and astronomers are very interested in them. These images show a green pea galaxy imaged by the Sloan Digital Sky Survey on the left and an infrared picture of an early pea captured by NASA’s James Webb Space Telescope. At left is J122051+491255, a green pea about 170 million light-years away that’s about 4,000 light-years across. That’s a typical size for a green pea. At right is an early pea known as 04590, whose light has taken 13.1 billion years to reach us.
“We’re seeing these objects as they existed up to 13.1 billion years ago when the universe was about 5% its current age,” said Goddard researcher Sangeeta Malhotra. “And we see that they are young galaxies in every sense – full of young stars and glowing gas that contains few chemical products recycled from earlier stars. Indeed, one of them contains just 2% the oxygen of a galaxy like our own and might be the most chemically primitive galaxy yet identified.
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CEERS Key Paper IV: The Diversity of Galaxy Structure and Morphology at z=3-9 with JWSTWe present a comprehensive analysis of the evolution of the morphological and structural properties of a large sample of galaxies at z=3-9 using early JWST CEERS NIRCam observations. Our sample consists of 850 galaxies at z|3 detected in both CANDELS HST imaging and JWST CEERS NIRCam images to enable a comparison of HST and JWST morphologies. Our team conducted a set of visual classifications, with each galaxy in the sample classified by three different individuals. We also measure quantitative morphologies using the publicly available codes across all seven NIRCam filters. Using these measurements, we present the fraction of galaxies of each morphological type as a function of redshift. Overall, we find that galaxies at z|3 have a wide diversity of morphologies. Galaxies with disks make up a total of 60\% of galaxies at z=3 and this fraction drops to ~30% at z=6-9, while galaxies with spheroids make up ~30-40% across the whole redshift range and pure spheroids with no evidence for disks or irregular features make up ~20%. The fraction of galaxies with irregular features is roughly constant at all redshifts (~40-50%), while those that are purely irregular increases from ~12% to ~20% at z|4.5. We note that these are apparent fractions as many selection effects impact the visibility of morphological features at high redshift. The distributions of Sérsic index, size, and axis ratios show significant differences between the morphological groups. Spheroid Only galaxies have a higher Sérsic index, smaller size, and higher axis ratio than Disk/Irregular galaxies. Across all redshifts, smaller spheroid and disk galaxies tend to be rounder. Overall, these trends suggest that galaxies with established disks and spheroids exist across the full redshift range of this study and further work with large samples at higher redshift is needed to quantify when these features first formed.
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Telescopes Reveal a Frenzy of Gas in Stephan’s QuintetData from Webb Space Telescope and ALMA reveals more about a group of five galaxies.
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New JWST Image Shows That Grand Spiral Galaxies had Already Formed 11 Billion Years agoFor the first time this week, photos from the James Webb Space Telescope (JWST) revealed that stellar bars were present in some galaxies as far back as 11 billion years ago. Stellar bars are a defining feature of about two-thirds of all spiral galaxies in the Universe, including our own Milky Way. The discovery has … Continue reading 'New JWST Image Shows That Grand Spiral Galaxies had Already Formed 11 Billion Years ago'
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James Webb Space Telescope spies massive shockwave and baby dwarf galaxy in Stephan's QuintetA shockwave traveling through Stephan's Quintet at over a million miles per hour is causing turbulence in between its five galaxies.
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James Webb Space Telescope detects a sonic boom bigger than Milky WayObservations made with JWST and ALMA allowed researchers to see the complex interactions within the multi-galaxy collision event known as Stephan's Quintet
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Early James Webb Space Telescope findings take center stage at key astronomy conferenceSharmila is a Seattle-based science journalist. She found her love for astronomy in Carl Sagan's The Pale Blue Dot and has been hooked ever since. She holds an MA in Journalism from Northeastern University and has been a contributing writer for Astronomy Magazine since 2017. Follow her on Twitter at Sharmilakg.
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