The James Webb Space Telescope’s stunning deep-infrared image of the universe has yielded 42 new, lensed images of galaxies, revealing an unprecedented depth of lensing that may eventually help us see the first galaxies.
Disclosure The James Webb Space Telescope A special deep field image by US President Joe Biden The White House incident Held on July 11, it was a closely guarded secret. Teams of astronomers raced to be the first to analyze it, with three new papers posted to the society’s preprint server a week after the image was released.
“To be honest, we were a bit side by side!” Brenda Frye, an astronomer at the University of Arizona’s Steward Observatory and co-author of one of the papers, told Space.com. “Usually we warn one or two years in advance, but no one saw it [this release] this time is coming.”
gallery: The first photographs of the James Webb Space Telescope
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The galaxy The cluster SMACS J0723.3-7327, known as SMACS J0723 for short, is one of the galaxy clusters that Webb imaged for various 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 lensing a phenomenon in which the gravity of a very large object bends space into an optical lens-like shape, resulting in the distortion and magnification of light from whatever is behind the lens. Galaxy clusters are particularly efficient lenses because they pack a large amount of mass (in the case of SMACS J0723, about 100 trillion times the mass of the sun) into a relatively compact volume about 3–5 million light-years in diameter. .
Previous surveys Hubble Space Telescope and retired Herschel Space Observatory They found a handful of lensed images of background galaxies in the SMACS J0723 observations. But Webb takes hunting to a whole new level.
Frye’s team, led by graduate student Massimo Pascala at the University of California, Berkeley, discovered 42 new lens images in the background of the new deep-field image. Gravitational lensing can produce 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 lens images.
Whatever the outcome, these lensed images allow scientists to map both what is visible and what matter looks like. dark — is distributed in the SMACS J0723 cluster and in turn models the shape of the lens. One new paper, from a team led by Guillaume Mahler of Durham University, concluded that most of the mass is concentrated in the brightest, most massive galaxy in the cluster.
“Our models not only describe the mass, but we can use them to describe the magnification of these lensed images,” Pascale told Space.com.
The most distant confirmed galaxy today is a distant object known as a galaxy GN-z11With a redshift of 11.09, that is, we see it as it existed 13.4 billion years ago, only 400 million years later. big bang. (“Redshift” refers to the stretching of the wavelength of light that occurs as the universe expands between a distant object and the viewer. The higher the redshift, the further away the light source is.)
It is an even more distant candidate HD1Discovered at 13 redshifts, it appears to us only 300 million years after the Big Bang. even recently First results from Webb They identified another candidate galaxy called GLASS-z11 at redshift 13. However, astronomers have yet to confirm the redshifts of HD1 or GLASS-z11.
Although it has yet to be determined whether any of the lensed galaxies seen in SMACS J0723 are more distant than Gn-z11 or HD1, Webb is expected to break these redshift records. Pascal and Frye are interested in mapping the so-called “critical curve” because it is along these curves that gravitational lensing exerts the greatest magnifying force and astronomers have the best chance of seeing these curves. the first galaxies.
“The typical magnification in a lensed cluster is about a factor of 10, which is not enough to see the first galaxies,” Frye said. “But if we look close to the critical curve, that’s where things are magnified hundreds or even thousands of times.”
Think of the critical curve as contour lines on a topographic map of the surface soil. The more such contour lines are connected, the greater the height of any particular spot on the surface. Similarly, the critical curve is where the contour lines of the gravitational potential accumulate, and the more they accumulate, the stronger this potential and monitoring magnification is. The location and shape of the lenticular images can indicate where the critical curve is.
“Ultimately, what we want to do is look along the critical curve where the magnification is highest, and we’ll find the highest redshift galaxies,” Frye said.
Hence why the first three new Webb Deep Field papers focus on modeling the amount and distribution of matter in the foreground cluster, resulting in the shape of the lens and the location of the critical curve.
However, modeling can also tell us about the history of the galaxy cluster itself.
“We found that mass distribution took a little longer than expected,” Pascale said. “Maybe that says something about him cluster merge dateand we can extrapolate from this and learn something about cluster formation in a very chaotic environment as a whole. weight all of these galaxies attract 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. In addition, Webb’s NIRISS (Near Infrared Imager and Slitless Spectrograph) data awaits analysis and should help scientists determine the spectroscopic redshifts of lensed galaxies and see how far away they are. (Deep-field image taken by NIRCam, Near Infrared Camera.)
“Before Webb described it, SMACS J0723 was not the star of the show,” Pascaly said. “Now all of a sudden there’s paper after paper on it that really speaks to how strong Webb is and reveals things we couldn’t see before.”
A preprint of Pascale and Frye’s paper can be found here here. Two other documents are available here and here.
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