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Massimo Pascale did not intend to investigate the SMACS 0723 galaxy cluster. However, as soon as he saw the cluster glistening in the first image captured by the James Webb Space Telescope, or JWST, he and his colleagues could not contain themselves. Pascale’s team is one of several groups of scientists who instantly rolled up their sleeves upon viewing the initial JWST photos. In the days following the release of photographs and the data used to make them, scientists have approximated the cluster’s mass, identified a cataclysmic event in the cluster’s recent past, and calculated the ages of stars in galaxies far outside the cluster.

“We have prepared for this for a very long time. Pascale, who is in his fourth year of graduate school, states, “I’ve been preparing for years, and I’m not even that old.” JWST “will define a new generation of astronomers and of science in general.”

When the image of SMACS 0723 was unveiled at a White House briefing on July 11, the background galaxies dominated the conversation (SN: 7/11/22). However, SMACS 0723, a galaxy cluster approximately 4.6 billion light-years from Earth, is located in the exact center of the image. Its mass refracts light from even greater distances, magnifying faraway objects as though their light had passed through another cosmic-sized telescope.

The light from the most distant galaxy in this image began its journey to JWST some 13.3 billion years ago, or “nearly at the beginning of the universe,” according to astrophysicist Guillaume Mahler of Durham University in England, who is currently using the image as his Zoom background. However, the image might also reveal the history of the galaxy cluster itself. People often overlook the significance of the galaxy cluster, according to Pascale.

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Pascale and Mahler’s teams cataloged the image’s remote galaxies. Some galaxies’ warped light creates many pictures of the same galaxy. Mapping galaxies with numerous pictures reveals cluster mass distribution. This can illustrate where the cluster contains dark matter, the majority of the universe’s mass (SN: 9/10/20). Both groups found that SMACS 0723 is longer than before. They also found a faint glow from stars that didn’t belong to any galaxy in the cluster. Two studies reveal that SMACS 0723 is still healing from a recent collision with another galaxy cluster.

A galaxy cluster that has been isolated for eons should have a more circular distribution of matter and intracluster light than SMACS 0723, which has an oblong shape. It is possible that the intracluster light stars were separated from their galaxies by gravitational forces during the collision. The problem appears to be unresolved despite the fact that two different clusters have merged. We may be considering a merger at this point.

Mahler explains that mapping out the cluster’s mass is also necessary for interpreting the features of the more distant galaxies in the image’s backdrop. “You must comprehend the cluster and its magnification capacity in order to comprehend what is behind.”

Some scientists are already conducting extensive research on these faraway galaxies. In addition to beautiful images, the initial JWST data include spectra, or measurements of the amount of light an object emits at various wavelengths. Scientists can use spectra to estimate the distance of a distant object by determining how much its light has been redshifted by the expansion of the cosmos. Such information can also disclose the composition and ages of a galaxy’s stars.

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“The fundamental factor limiting the study of star formation in galaxies is the quality of the data,” says University of Edinburgh astronomer Adam Carnall. However, using the considerably enhanced JWST data, he and his team were able to determine the ages of the stars in these distant galaxies.

A few days after the SMACS image was released, Carnall and his colleagues shifted their focus to the spectra of the distant galaxies. The researchers measured the redshifts of ten galaxies, five of which were exceptionally far away, according to a publication posted on on July 18. One was previously identified as the most distant galaxy ever observed, with light released only 500 million years after the Big Bang 13.8 billion years ago. The other four began to shine approximately 1,100,000,000 years after the Big Bang.

Carnall states that all ten galaxies were reasonably young when they released the light collected by JWST. They had all initiated star creation only a few million years prior. This is not really shocking, but it is intriguing.

We can learn a lot about the formation of stars in galaxies by observing these small, faint galaxies. JWST is being used to look for the initial signs of star formation. Preliminary evidence suggests that they are currently within striking distance. ” According to two study teams, some galaxies in a JWST image of another cluster may have been around for as long as 300 million years after the Big Bang. It appears that at least one of these young galaxies generated a spiral disk with a mass nearly a billion times greater than the sun’s.

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And a count of galaxies visible in the SMACS 0723 image implies that galaxies with mature disks, rather than chaotic blobs or ones composed primarily of dark matter, may have been more prevalent in the very early universe than previously believed, according to a July 19 publication posted on This indicates that the early disks may not be anomalies. It remains to be seen how interesting these galaxies will appear in the context of the JWST’s work over the next few months, Carnall says. The greatest is still ahead.

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