JWST Reveals a Surprisingly High Fraction of Galaxies Being Spiral-like

arXiv:

In this letter, we used James Webb Space Telescope (JWST) images from the Cosmic Evolution Early Release Science Survey to visually identify spiral galaxies with redshift 0.5≤z≤4 and stellar mass ≥1010M⊙. Out of 873 galaxies, 216 were found to have a spiral structure.

These fractions are higher than the fractions observed with the Hubble Space Telescope (HST). We even detect possible spiral-like features at redshifts z>3.

This fraction is surprisingly high and implies that the formation of spiral arms, as well as disks, was earlier in the universe. 

Phys.org:

Of these galaxies, 216 were classified as spirals. The authors were careful to note that some may be merging galaxies that were misclassified, but even then 108 of the galaxies were unanimously classified as spirals by evaluators. When the team arranged them by redshift, they found that while the fraction of spirals decreased as you went further into the past, the fraction of spirals at redshifts above z = 3 was much higher than expected. When the team calibrated observations, they found about a fifth of galaxies at z = 3 are spiral galaxies. These very early galaxies would have had to become spirals less than two billion years after the Big Bang, meaning that there would have been little time for mergers and collisions to be the cause.

If spiral galaxies were more common in the early universe than expected, it could indicate that certain conditions or mechanisms favored the formation of spiral structures at that time. This is quite at odds with the current understanding of what structures were favored during these early epochs of the Universe's development.

Previously on this blog:

•  James Webb captures an extremely distant triple-lensed supernova
•  Webb telescope discovers oldest galaxies ever observed  
•  Discovery of an isolated dark dwarf galaxy in the nearby universe

Webb telescope discovers oldest galaxies ever observed

Nature Astronomy:

Here we identify four galaxies located in the JWST Advanced Deep Extragalactic Survey Near-Infrared Camera imaging with photometric redshifts z of roughly 10–13. These galaxies include the first redshift z > 12 systems discovered with distances spectroscopically confirmed by JWST in a companion paper.

Taken together, these measurements show that the first galaxies contributing to cosmic reionization formed rapidly and with intense internal radiation fields.

Phys.org:

The James Webb Space Telescope has discovered the four most distant galaxies ever observed, one of which formed just 320 million years after the Big Bang when the universe was still in its infancy, new research said on Tuesday.

Stephane Charlot, a researcher at the Astrophysics Institute of Paris and co-author of the two new studies, told AFP that the farthest galaxy—called JADES-GS-z13-0—formed 320 million years after the Big Bang. That is the greatest distance ever observed by astronomers, he said.

However in February, the discovery of six massive galaxies from 500-700 million years after the Big Bang led some astronomers to question the standard model.

Those galaxies, also observed by the Webb telescope, were bigger than thought possible so soon after the birth of the universe—if confirmed, the standard model could need updating. 

This analysis does not include even earlier candidates that JWST has discovered that are yet to be confirmed. 

Webb telescope spots super old, massive galaxies that shouldn’t exist

Nature:

Here we make use of the 1-5 μm coverage of the JWST early release observations to search for intrinsically red galaxies in the first ≈ 750 million years of cosmic history. In the survey area, we find six candidate massive galaxies (stellar mass > 1010 solar masses) at 7.4 ≤ z ≤ 9.1, 500–700 Myr after the Big Bang, including one galaxy with a possible stellar mass of ~1011 solar masses.

If verified with spectroscopy, the stellar mass density in massive galaxies would be much higher than anticipated from previous studies based on rest-frame ultraviolet-selected samples.

They posit two scenarios:

We infer that the possible interpretation of these JWST-identified “optical break galaxies” falls between two extremes. If the redshifts and fiducial masses are correct, then the mass density in the most massive galaxies would exceed the total previously estimated mass density...

The other extreme interpretation is that all the fiducial masses are larger than the true masses by factors of >10-100.

It will be extremely exciting to see if these mass density estimates are validated.

CU Boulder:

In a new study, an international team of astrophysicists has discovered several mysterious objects hiding in images from the James Webb Space Telescope: six potential galaxies that emerged so early in the universe’s history and are so massive they should not be possible under current cosmological theory.

“It’s bananas,” said Erica Nelson, co-author of the new research and assistant professor of astrophysics at CU Boulder. “You just don’t expect the early universe to be able to organize itself that quickly. These galaxies should not have had time to form.”

She explained that in astronomy, red light usually equals old light. The universe, Nelson said, has been expanding since the dawn of time. As it expands, galaxies and other celestial objects move farther apart, and the light they emit stretches out—think of it like the cosmic equivalent of saltwater taffy. The more the light stretches, the redder it looks to human instruments. (Light from objects coming closer to Earth, in contrast, looks bluer)...The team ran calculations and discovered that their old galaxies were also huge, harboring tens to hundreds of billions of sun-sized stars worth of mass, on par with the Milky Way.

Mashable:

While scanning a region of the cosmos near the Big Dipper, a group of astronomers identified six faint objects as they appeared well over 13 billion years ago. They suspect the objects are ancient galaxies. Scientists expect such early collections of stars and swirling matter to be relatively small. After all, such galaxies hadn't had much time to form or grow. But these galaxies are giants, the researchers report.

"If even one of these galaxies is real, it will push against the limits of our understanding of cosmology,” Nelson noted.

 

Discovery of an isolated dark dwarf galaxy in the nearby universe

arXiv (accepted for publication in ApJ):  

Based on a new H I survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with the Pan-STARRS1 images, we identified an isolated H I cloud without any optical counterpart, named FAST J0139+4328...These findings provide observational evidence that FAST J0139+4328 is an isolated dark dwarf galaxy with a redshift of z = 0.0083.

Moreover, this disk galaxy has an extremely low absolute magnitude (M_B >-10.0 mag).

This is an insanely low absolute magnitude. For reference, a normal absolute magnitude for a galaxy like this might be around 10.

Furthermore, we obtained that the H I mass of this galaxy is (8.3±1.7)e7 SM, and the dynamical mass to total baryonic mass ratio is 47±27, implying that dark matter dominates over baryons in FAST J0139+4328. 

That's a substantial error bar--I wonder if future observations can constrain that much better.

ScienceAlert:

And they got a hit: the radio waves emitted by a cloud of HI 94 million light-years away were consistent with a rotating disk galaxy, without the optical light expected of one. Follow-up observations in infrared and ultraviolet revealed a faint smattering of stars.

 "This is the first time that a gas-rich isolated dark galaxy has been detected in the nearby Universe," the researchers write.

There are a few other dark galaxy candidates, namely HI 1225+01 (ADS) and HI1232+20 (arXiv).