A breathtaking deep-infrared image of the universe by the James Webb Space Telescope has revealed 42 new images of lensed galaxies and revealed an unprecedented depth of lens shape that could eventually help us see the very first galaxies.
Disclosure James Webb Space Telescope deep field image taken by US President Joe Biden in a special Event at the White House held on July 11 was strictly classified. Teams of astronomers sought to be the first to analyze it, and within a week of the image’s release, three new papers were submitted to the community preprint server.
“Honestly, we were a bit taken aback!” Brenda Fry, an astronomer at the University of Arizona’s Steward Observatory and co-author of one of the papers, told Space.com about this. “Usually we have a warning for a year or two, but no one has seen [this release] will come at this time.”
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galaxy SMACS J0723.3-7327, known as SMACS J0723 for short, is one of the galaxy clusters that Webb visualizes for various gravitational lensing surveys. Beyond that, according to Fry, there was nothing exceptional about SMACS J0723—until now.
“Wonderfully chosen [to be one of the first images] because it was a relatively unknown target,” she said.
Gravitational lensing it is a phenomenon in which the gravity of a very massive object warps space into a shape similar to an optical lens, causing the light from what is behind the lens to be distorted and increase in brightness. Galaxy clusters are particularly effective lenses because they pack a huge amount of mass (in the case of SMACS J0723, about 100 trillion times the mass of the Sun) into a relatively compact volume 3 to 5 million light-years in diameter. .
Previous Polls Hubble Space Telescope and pensioner Herschel Space Observatory found several lens images of background galaxies in their observations of SMACS J0723. But Webb takes hunting to a whole new level.
Fry’s team, led by UC Berkeley graduate student Massimo Pascal, discovered 42 new lensed images against a new deep-field image. Gravitational lenses can create multiple images of the same galaxy, so these 42 images represent 19 separate galaxies. Another team, led by Gabriel Caminha of the Max Planck Institute for Astrophysics in Germany, counted 27 new lens images.
Whatever the final results, these lens images allow scientists to fine-tune the map of how matter—both visible and dark – is distributed in the SMACS J0723 cluster and, in turn, models the shape of the lens. In one of the new papers, a group led by Guillaume Mahler of Durham University concluded that most of the mass is concentrated in the brightest and most massive galaxy in the cluster.
“Our models not only describe mass, but we can also use them to describe the magnification of these lens images,” Pascal told Space.com.
The current most distant confirmed galaxy is a distant object known as GN-z11whose redshift is 11.09, that is, we see it as it existed 13.4 billion years ago, just 400 million years after Big Bang. (“Redshift” refers to the stretching of the wavelength of light that occurs when the universe expands between a distant object and an observer. The higher the redshift factor, the further away the light source.)
An even more distant candidate HD1, found at redshift 13, appears to us as it was just 300 million years after the Big Bang. More recently, first results from Webb identified another candidate galaxy at redshift 13, named GLASS-z11. However, astronomers have yet to confirm the redshift of either HD1 or GLASS-z11.
Webb is expected to break both of these redshift records, although it remains to be determined whether any of the lensed galaxies seen in SMACS J0723 are more distant than Gn-z11 or HD1. Pascal and Fry are interested in mapping a phenomenon called the “critical curve” because it is along these curves that the gravitational lens exerts the most magnifying force, and it is there that astronomers have the best chance of seeing the earliest galaxies.
“Typical magnification in a lens cluster is about 10x, which is not enough to see the first galaxies,” Fry said. “But if we look at the critical curve, we see that everything increases hundreds or even thousands of times.”
Think of the critical curve as contour lines on a topographic map of the surface. Earth. The more such contour lines grouped together, the greater the height of any particular spot on the surface. Similarly, the critical curve is where the contour lines of the gravitational potential are clustered, and the more they cluster, the stronger this potential and the increase that accompanies it. The location and shape of the lens images can indicate where the critical curve lies.
“Ultimately, we want to look straight along the critical curve where the magnification is greatest, and that’s where we’ll find the galaxies with the highest redshift,” Fry said.
This is why the original three new papers on Webb’s deep field focus on modeling the amount and distribution of matter in a foreground cluster and hence on the shape of the lens and the location of the critical curve.
However, simulations can also tell us about the galaxy cluster’s own history.
“We found that the mass distribution was a bit more elongated than expected,” Pascal said. “Perhaps this says something about cluster merge historyand we can extrapolate this and learn something about the formation of the cluster as a whole, which takes place in a very chaotic environment where gravity All these galaxies are attracted to each other.
The immediate next step for the Pascal and Fry team, as well as the authors of the other two papers, is to go through a peer review process to see the results published in scientific journals. In addition, data from Webb’s NIRISS (near infrared imaging instrument and slitless spectrograph) is awaiting analysis 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 the NIRCam near-infrared camera.)
“Before Webb photographed it, SMACS J0723 was not the star of the show,” Pascal said. “Now, all of a sudden, it has paper after paper on it that really speaks to how powerful Webb is to uncover things we couldn’t see before.”
A preprint of the paper by Pascal and Fry can be found here. Two other documents are available here as well as here.
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