The James Webb Space Telescope’s spectacular image of the deep infrared universe has uncovered 42 new images of lensed galaxies and revealed in unprecedented depth the shape of the lens, which may eventually help us see the first galaxies.
The revelation of James Webb Space Telescope deep field image, by US President Joe Biden in a special white house event held on July 11, was a closely guarded secret. Teams of astronomers scrambled to be the first to analyze it, and three new articles were posted on the community preprint server a week after the image was published.
“We got hit a bit, to be honest!” Brenda Frye, an astronomer at the University of Arizona Steward Observatory and a co-author on one of the papers, told Space.com. “Normally we have a year or two in advance, but no one saw [this release] coming right now.”
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the galaxy the cluster SMACS J0723.3-7327, known as SMACS J0723 for short, is among a set of galaxy clusters that Webb is imaging for several gravitational lensing studies. Beyond that, Frye said, there was nothing exceptional about SMACS J0723, until now.
“It was very well chosen. [to be one of the first images] because it was a relatively unknown target,” he said.
gravitational lens is a phenomenon in which the gravity of a very massive object warps space in a way analogous to an optical lens, causing the light from whatever is behind the lens to become distorted and brighter. Galaxy clusters are particularly efficient lenses because they contain a large amount of mass (in the case of SMACS J0723, about 100 billion times the mass of the Sun) in a relatively compact volume with a diameter of about 3 to 5 million light years. . . .
Previous surveys of the hubble space telescope and retirees Herschel Space Observatory he had found a handful of lensed images of background galaxies in his SMACS J0723 observations. But Webb takes hunting to a whole new level.
Frye’s team, led by graduate student Massimo Pascale of the University of California, Berkeley, discovered 42 new lensed images in the background of the new deep-field image. Gravitational lensing can create multiple images of the same galaxy, so these 42 images represent 19 individual galaxies. Another team, led by Gabriel Caminha of the Max Planck Institute for Astrophysics in Germany, counted 27 new lensed images.
Whatever the final tally, these lensed images allow scientists to fine-tune a map of how matter, both visible and Dark — is distributed in the SMACS J0723 cluster and, in turn, models the shape of the lens. One of the new papers, by a team led by Guillaume Mahler of Durham University, concluded that most of the mass is centered in the brightest and most massive galaxy in the cluster.
“Our models not only describe mass, but we can also use them to describe magnification of these lensed images,” Pascale told Space.com.
The current most distant confirmed galaxy is a distant object known as GN-z11which has a redshift of 11.09, which means we see it as it existed 13.4 billion years ago, just 400 million years after the big Bang. (“Redshift” refers to the stretching of the wavelength of light that occurs when the universe expands between a distant object and the observer. The larger the redshift factor, the more distant the source of light).
An even more distant candidate is HD1, discovered at a redshift of 13, appears to us as it did only 300 million years after the Big Bang. Even more recently, Webb’s first results have identified another candidate galaxy at redshift 13, called GLASS-z11. However, astronomers have not yet confirmed the redshifts of HD1 or GLASS-z11.
Webb is expected to break both of these redshift records, although it has not yet been determined whether any of the lensed galaxies seen in SMACS J0723 are more distant than Gn-z11 or HD1. Pascale and Frye are interested in mapping a phenomenon called the “critical curve,” because it is along these curves that gravitational lensing applies the greatest magnifying power and that astronomers have the best chance of seeing the sun. first galaxies.
“Typical magnification in a lensed cluster is a factor of 10, and that’s not enough to see the first galaxies,” Frye said. “But if we look near the critical curve, that’s where things get magnified hundreds or even thousands of times.”
Think of a critical curve as if they were contour lines on a topographical map of the earth’s surface. Land. The more these contour lines are grouped together, the greater the height of any particular point on the surface. Similarly, a critical curve is where the contour lines of the gravitational potential stack up, and the more they stack up, the stronger that potential and its accompanying rise. The location and shape of the lensed images can give an indication of where the critical curve lies.
“Ultimately, what we want to do is look along the critical curve where the magnification is greatest, and that’s where we’ll find the highest redshift galaxies,” Frye said.
Hence the initial trio of new papers on Webb’s deep field concentrate on modeling the amount and distribution of matter in the foreground group, and consequently the shape of the lens and the location of the critical curve.
However, modeling can also tell us about the galaxy cluster’s own history.
“We found that the mass distribution was a bit longer than expected,” Pascale said. “Maybe that says something about the cluster merge historyand we can extrapolate from that and learn something about group formation as a whole, which occurs in a very chaotic environment where gravity of all these galaxies are pulling each other”.
The immediate next step for Pascale and Frye’s team, and the authors of the other two papers, is to go through the peer review process to see these results published in scientific journals. Beyond that, Webb’s Near Infrared Imager and Slitless Spectrograph (NIRISS) data is waiting to be analyzed and should help scientists determine the spectroscopic redshifts of lensed galaxies and see how far away they are. . (The deep field image was captured by NIRCam, the near-infrared camera.)
“Before Webb photographed it, SMACS J0723 was not the star of the show,” Pascale said. “Now all of a sudden there’s paper after paper, which really speaks to how powerful Webb is, to reveal things we couldn’t see before.”
The preprint of Pascale and Frye’s article can be found here. The other two papers are available. here Y here.
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