In a cosmological matchup of “Are they or aren’t they?” The contest is entirely in favor of the former, ending 10 to 1. Are the galaxies that the James Webb Space Telescope (JWST) sees in the early universe as surprisingly far away as we think they are? So far, the answer is yes. “The majority of these galaxies have been confirmed,” says Steven Finkelstein, an astronomer at the University of Texas at Austin. That means everything we saw last summer will continue.”
In the summer of 2022, JWST has unleashed a plethora of discoveries. Launched in December 2021 and more than half a year after commissioning, JWST will fully switch on in July 2022. Almost immediately, its unprecedented infrared sensitivity revealed the galaxy’s faint glow. Millions of years after the big bang. Astronomers expected such breakthrough results to appear more gradually. “There has been an explosion of data,” says Finkelstein.
These early results came very quickly because the researchers used clever shortcuts to estimate the distances of the galaxies. Astronomers usually pinpoint cosmic coordinates by measuring redshifts precisely. This is the stretching of galactic light towards the red end of the electromagnetic spectrum as a result of the expansion of the universe. But this requires work to assemble and analyze the galaxy’s spectrum. This is a time-consuming and delicate process known as spectroscopy. The firehose of the JWST discovery was instead augmented by a cruder and faster photometry-based technique that essentially uses apparent changes in the brightness of galaxies to estimate redshifts.
Thus, while photometric results thickened and quickened last summer, spectroscopic results are just beginning to drip. However, only about a dozen candidates have spectral-based distances at hand, and researchers have already found that most of the measurements agree with initial photometric results.The latest published in natural astronomy Last week, we confirmed previous distance estimates for four more galaxies identified by the JWST Advanced Deep Extragalactic Survey (JADES). “We’ve been waiting for this for decades,” says Emma Curtis-Lake, from the University of Hertfordshire in England, who led the study of the spectroscopic results. “It was incredible to be able to do that in the first few months with this telescope.”
The farthest of the four is JADES-GS-z13-0 with the somewhat awkward name. Its redshift value is 13.2, meaning we are looking at a galaxy that appeared just 320 million years after the Big Bang. Its high redshift makes JADES-GS-z13-0 the most distant in the currently known universe. JWST appears set to break the imminent record yet again, highlighting why astronomers are so excited. We are now convinced that mankind is investigating an age of space never seen before. . He provocatively points out that this galaxy is only slightly younger from our perspective than the total time sharks have been on Earth (about 300 million years). “You get to these fully formed galaxies in the blink of an eye out of nothing,” says van Dokkum.
But not all high-redshift candidate galaxies were so lucky, highlighting the early caution of astronomers. In July, another survey called the Cosmic Evolution Early Release Science Survey (CEERS), led by Finkelstein, discovered a possible galaxy with a redshift of 16.4, just 240 million years after the Big Bang. Subsequent spectroscopy showed that the deduction was wrong, as he revealed in late March in a study led by Pablo Haro, an astronomer at his NOIR Lab at the National Science Foundation. This galaxy is actually a dusty imposter located at redshift 4.9, and he’s still impressive 1.2 billion years after the Big Bang, but not a record breaker. High levels of star formation are thought to have confounded early photometric analyses. “We can be easily fooled by pollution,” says co-author of the study, Callum Donan of the University of Edinburgh in Scotland. “High-redshift galaxies can be mimicked by low-redshift galaxies with different characteristics.”
The good news is that this particular galaxy looks like a “unique case,” Donnan says. One of his is the Maisie Galaxy, seen at redshift 11.4 about 400 million years after the Big Bang and named after Finkelstein’s daughter. “She was so excited when I said I was real,” says Finkelstein.
Now that such galaxies have been identified, their scientific implications can be explored more fully. These galaxies are small, many times smaller than the Milky Way. However, some appear very bright and huge, and have a high star formation rate similar to our own Milky Way, forming about one new star each year. Galaxies have not yet challenged major models of cosmology, but they do suggest that galaxy formation began earlier and progressed faster than expected in the universe. Bang.
“We are seeing the rise of massive galaxies at a faster rate than previously thought,” said Fabio Pacucci of the Harvard-Smithsonian Center for Astrophysics. The ages of some of these early galaxies are estimated to be only tens of millions of years. This may influence the large structures of dark matter known as halos that shaped early galaxies, as well as the properties of the dark matter particles themselves. “One of the big open questions is: teeth dark matter? says Sandro Takera of the University of Cambridge. “The first generation of galaxies is a sensitive probe for various dark matter models.”
There are still some early universe candidate galaxies that are problematic and potentially model-destroying. The first of them may be the galaxy class identified by Ivo Labbé and his colleagues at Swinburne University of Technology in Australia. The team discovered a galaxy with billions of solar masses, comparable to the Milky Way, an estimated 750 million years after the Big Bang. These galaxies are 10 to 100 times larger than galaxies seen previously in this era and are packed into a structure 30 times smaller than the Milky Way. “They’re small, but they’re huge,” he says Labbé. JWST says it continues to find similar galaxies essentially anywhere it can be seen deep in the sky. For now, the galaxy has been studied only by photometry, with spectroscopy planned for July. However, the photometric success of other JWST results to date suggests that the preliminary analysis of Labbé and his colleagues is correct. “The most extreme galaxies out there still seem to pose a problem,” says Michael Boylan-Kolchin of the University of Texas at Austin. “Some of these systems have to form stars 1,000 times faster than he does in the Milky Way. The question is, is it an incredibly large amount of star formation?”
This field continues to change rapidly. An ongoing survey called COSMOS-Webb is expected to yield many more high-redshift candidates. “Our estimate in the proposal was [to find galaxies] Redshifts of up to 10 or so,” says Jeyhan Kartaltepe of the Rochester Institute of Technology, who is leading the program. “But these numbers may be too pessimistic.” Many other astronomers submitted requests for additional free time at the telescope to the Space Telescope Science Institute in Maryland, which runs the observatory. Did. Many proposals are still being submitted for his second year of scheduled scientific observations for the telescope, called Cycle 2, which begins in July.
Some worry that the field is moving too fast. Much of the JWST data (about 80%) has a unique window of 12 months in which responsible researchers have exclusive access to their own observations, while the rest are open access. This means that once an observation is made, it is immediately available to the public and available for anyone to use. Before Haro and his colleagues published their analysis of a redshift 16.4 galaxy in a preprint on his server arXiv.org in late March, their open-access research was scooped by an astronomer on his Twitter account. It was done. Gabriel Brammer of the University of Copenhagen said: some early results“The team did a more in-depth analysis. But if you know where to look, you can see it right away.”
Not everyone is happy with such easy access. Rebecca Larson of her UT Austin, co-author of Haro’s paper and part of her CEERS team, said: “Then our data is public and people are competing against us for results. People come in and put up paperwork, and it’s really frustrating to see what’s going on.” It’s unclear how the tension will be resolved at this time. “It would be nice if there were more specific rules,” says Tom Bucks of Nagoya University in Japan, who was not involved in the research. “It’s impossible to spend all night reconciling data when you have small children. It’s a bit of an imbalance of power. It’s a very open competition.”
On a more positive note, things seem to have cooled somewhat from the frenzied early weeks of JWST. Now astronomers are doing what they have long dreamed of. It offers the first glimpse into an age of the universe that has never been studied before. No one knows how far ahead we will look. “Galaxy formation may have already begun at his 20 redshift,” says van Dokkum, referring to a time point just 180 million years after the Big Bang. bottom. But if telescopes show us anything, it’s to expect the unexpected.
