Astronomers are now discovering a record-breaking record-breaking tens of distant galaxies while sifting through the treasure trove of data now collected by the James Webb Space Telescope (JWST, or Webb). Among them are several galaxies dating back a little over 200 million years after the Big Bang.
before launch James Webb Space Telescopethe most distant confirmed galaxy known was GN-z11which astronomers saw about 420 million years later the great explosiongiving it what astronomers call a redshift from 11.6. (Redshift describes how much light coming from a galaxy is stretched as the letter uThe universe is expanding. The greater the redshift, the farther in time we see the galaxy.)
Just a week after the release The first scientific pictures From JWST, astronomers have been reporting the discovery of galaxies in redshift 13, equivalent to about 300 million years after the Big Bang. Now, a new wave of scientific results has broken that record, with some astronomers reporting discovering galaxies up to a redshift of 20. If true, we see these galaxies as they existed about 200 million years after the Big Bang.
Gallery: The first images of the James Webb Space Telescope
This is big if: at this point, none of these redshift values have been confirmed. To confirm the distances of these galaxies will require spectroscopy, which splits the light from an object into what scientists call the spectrum. This analysis will come later. However, it seems clear that JWST is perfectly capable of detecting galaxies from this long lost age.
Galaxies were discovered using different techniques. Astronomers led by Haojing Yan from the University of Missouri-Columbia gravity lens Created by Galactic Cluster SMACS J0723 to detect 88 candidate galaxies with a redshift of 11, including a handful of galaxies estimated with a redshift of 20. If validated, these galaxies would be, by far, the farthest distance ever detected. Due to cosmic expansion, today these galaxies will be more than 35 billion light-years away from us.
Two other papers reported the discovery of highly redshifted galaxies in patches of sky where JWST simply underwent deep exposures, without resorting to gravitational lensing. These images are part of the Early Cosmic Evolution Propagation Science Survey (CEERS), which consists of images of 10 different spots of the sky by JWST’s Near Infrared Camera (NIRCam). JWST near infrared spectrometer NIRSpec joins observations of six of those spots, while the Space Telescope’s Mid-Infrared Instrument (MIRI) studies four.
One team of astronomers led by Ph.D. Student Callum Dunant of the University of Edinburgh has found a candidate galaxy at a redshift of 16.7, which is just 250 million years after the Big Bang. The team also found five other redshift galaxies greater than 12, all exceeding the redshift record set by JWST’s predecessor and now colleague, Hubble Space Telescope.
Meanwhile, using the same observations from CEERS, another team led by Stephen Finkelstein of the University of Texas at Austin has discovered a redshifted 14.3 galaxy, placing it 280 million years after the Big Bang, which the researchers named the “Maisi Galaxy” after Finkelstein’s daughter . Astronomers found that this galaxy may also have been seen by the Hubble Space Telescope, but it was not recognized at the time. If a closer look at archived data reveals the galaxy, the Maisie Galaxy should be producing very strong ultraviolet light from a powerful explosion of star formation for Hubble to spot.
In fact, all the distant candidate galaxies display evidence of strong ultraviolet emission, perhaps enough to settle the debate about why hydrogen gas in the universe is ionized, and put an end to the so-called “cosmic dark agesOver the years, astronomers have proposed causes ranging from radiation from the first stars and galaxies to outflows of radiation from the first supermassive black holes.
In their paper, Donnan’s team calculated a “galaxy ultraviolet luminosity function” between a redshift of 8 and 15. This function is the average amount of ultraviolet light associated with galaxies in any given epoch. The value is closely related to star formation, because the more hot young stars in the galaxy, the more ultraviolet light they emit. Dunant’s team concluded that there was enough ultraviolet radiation produced by stars in these early galaxies to ionize the universe.
The large number of high redshift galaxies being discovered can be considered cosmic babies. These galaxies are only 1,000 light-years across and contain tens of millions of stars. Modern galaxies can host hundreds of billions of stars. Astronomers estimate that cosmic children are less than 100 million years old, and may be as old as 20 million years old.
Scientists have not yet identified any of the first galaxies in the universe, which might lie at redshift 25 or beyond. However, the new discoveries represent generations of galaxies that followed closely, and which scientists see in the early stages of evolution.
The amount of ultraviolet light (slithering toward the red to longer infrared wavelengths, making them visible to JWST), along with the abundance of high redshift galaxies that it detected so early in its mission, suggest that galaxies were abundant at the earliest date. For JWST Universe. Contrary to some predictions, the rate of star formation may gradually decline as we look back, rather than a sharp decline after redshift 11.
“Spectral validation should continue [these redshifts]And the [it means that] Our universe was already glowing with galaxies less than 300 million years after the Big Bang,” Finkelstein’s team wrote in their paper.
Now that JWST has detected these powerful candidate galaxies over vast distances, the next questions are how far in the past the JWST could see and whether it would be enough to discover the first galaxies found, perhaps only 100 million years after the Big Bang. Such a discovery would require a great deal of luck, as it would rely on the tangential gravitational lensing to show primeval galaxies.
Yan paper can be found over here; donan paper over here; The Finkelstein paper over here.
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