2023-11-02 11:54:33
This image shows Webb’s First Deep Field of Galaxies, the first scientific image revealed by JWST. – NASA, ESA, CSA, STSCI.SMU
MADRID, 2 Nov. (EUROPA PRESS) –
A study of the first image of the deep universe from the Webb Space Telescope, published on July 11, 2022has now made it possible to know how far the Earth is from 200 galaxies
That image is called Webb’s First Deep Field and is centered on a galaxy cluster called SMACS 0723 and which contains no less than 7,000 galaxiesmany of them very distant that shed light on how galaxies formed and evolved in the early universe.
A team of Canadian and international astronomers led by Dr. Gaël Noirot, a postdoctoral researcher at Saint Mary’s University in Halifax, has carefully surveyed and analyzed Webb’s first deep field. His study is published in Monthly Notices of the Royal Astronomical Society.
Members of the Canadian NIRISS Unbiased Cluster Survey (CANUCS), scientists used the Canadian NIRISS (Near Infra-Red Imager and Slitless Spectrograph) instrument aboard JWST to collect galaxy spectra target in the image. These spectra are a type of scientific data created by breaking down light from an object to reveal additional information, such as the age or distance of the object.
Using JWST’s NIRISS instrument, built in Canada, the team measured the “redshifts” (shifts in the spectra of very distant galaxies toward longer wavelengths) of nearly 200 galaxies whose distances to Earth were previously unknown. “NIRISS is perfect for doing this because it can measure the redshifts of hundreds of galaxies at once,” he said. it’s a statement Noirot, lead author of the study.
“Redshift” is a precise measure of a galaxy’s distance based on the unique chemical signatures seen in its spectra. Because the universe is expanding, light emitted by distant objects such as galaxies is stretched and its spectral characteristics are seen at longer (i.e., redder) wavelengths than originally emitted. This redshift, which is the difference between the observed color and that emitted by an object, reveals its distance from Earth.
“Our work on SMACS 0723, the first deep Webb field and the first scientific image ever published by JWST, has produced the largest JWST spectroscopic catalog of its kind with reliable redshift measurements,” said co-author Marcin Sawicki, professor and Canada Research Chair at Santa Maria. “Our recently published study will be a valuable resource for the astronomical community and open new avenues of research“Noirot added.
From this redshift catalog, researchers have discovered many new galaxies in the SMACS 0723 cluster whose light has taken more than 4 billion years to reach us. Clusters, which are huge groups of galaxies held together by the force of gravity, can contain up to thousands of galaxies.
Within their huge collection of galaxy redshifts, the researchers identified three other galaxy overdensities at distances much greater than SMACS 0723 that had not previously been seen in this field. These galaxy overdensities are potentially newly discovered galaxy clusters located between eight and 10 billion light years away.
Capturing these overdensities of galaxies at different cosmic moments is like watching a fast-motion movie of the growth of these clusters, from his childhood in a young universe to the present day.
Clusters represent ideal targets for future studies to better understand how galaxies and the clusters they inhabit have evolved from their state in the early universe to what they look like today, including our own Milky Way galaxy, scientists say.
The CANUCS team has already made a surprising find within one of these clusters: the magnificent Sparkler galaxy. Discovered in September 2022, it is a greatly expanded galaxy, about 9 billion light years away, filled with what appear to be the oldest star clusters that formed after the Big Bang.
What the team’s new NIRISS redshift catalog now reveals is that Sparkler is not an isolated galaxy, but rather resides in one of the newly discovered galaxy overdensities.
“The fact that Sparkler does not live alone but is a member of a family of galaxies has important implications for how the first star clusters formed after the Big Bang,” said Sawicki, co-author of the previous study.
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