The Alternate View

The Jwst And Early Universe Puzzles
by John G. Cramer

On Christmas Day of 2021 NASA boosted the James Webb Space Telescope (JWST) into a stable L2 Sun-Earth orbit. About six months later JWST began its astronomical observations, and it has now been in full operation for almost three years. Its radical layered sun-shield design allows for its detector system to operate at ultra-cold cryogenic temperatures, so that light in the infrared regime, normally obscured by the thermal emissions of the detector system itself, can provide images of very distant and highly red-shifted objects that may have no significant emissions in the visible light regime.

This has made it possible to probe the stars, galaxies, and black holes that formed just after the Big Bang, when the universe had expanded enough for atomic hydrogen to form and had cooled just enough for the first stars to coalesce out of the primordial gaseous medium. The early-universe objects that have emerged from these first JWST images do not fit well with our current cosmological understanding, and astrophysics now has a major revolution in progress. Something quite unexpected and unanticipated by prior simulations was going on in the early universe, and for the community of astrophysicists that is very exciting and challenging.

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One of the new wonders revealed by the JWST is the galaxy JADES-GS-z14-0, which currently holds the record as the oldest galaxy ever observed. It was formed about 290 million years after the Big Bang, at about 2% of the current age of the universe. It has a record red-shift factor of z=14.32, making it the most distant galaxy ever discovered. It is located in the southern celestial hemisphere in the constellation Fornax, a diamond-shaped group of four bright stars. Distinguishing features of JADES-GS-z14-0 are that it is far larger, brighter, and presumably more massive than was expected for such an early galaxy, it shows characteristics of strong ionized gas emissions, including those from oxygen, and its light output in the ultraviolet falls off too fast to be consistent with any significant contribution to its light output from a central black hole. Its diameter is estimated to be around 1,600 light-years, much smaller than that of the Milky Way or Andromeda but quite large for an early galaxy. Its oxygen content suggests that generations of massive stars must have previously lived, died, and exploded before it came into existence, in order to produce by stellar fusion the quantity of oxygen observed from its light spectrum. Astrophysical theorists are currently spinning many theories about how such brightness, mass, and oxygen content are possible in this oldest of galaxies.

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Another unexpected object discovered by the JWST (and followed up by the Chandra X-Ray Observatory) is the “over massive” black hole that lies within the Compton-thick type 2 quasar named UHZ1. The quasar has a red-shift factor of k=10.1, indicating that it formed about 470 million years after the Big Bang, when the universe was only 3% of its current age. Type 2 quasars have narrow emission lines, and a Compton-thick quasar typically has a large gas density (~1.5 x 10²⁴ hydrogen atoms per cm³) that absorbs most of the quasar’s x-ray emissions. Based on its light and x-ray output, the central black hole of UHZ1 has an estimated mass of around 40,000,000 solar masses. For comparison, that is about 10 times the mass of the black hole at the center of our Milky Way galaxy.

There is a timing problem with the existence of such a massive black hole in the early universe. Astrophysicists usually assume that black holes originate in the collapse of massive stars and then gradually increase their mass by capturing and consuming ambient gas and nearby stars. However, such star formation, collapse, and capture all require significant times, and there was simply not enough time after the Big Bang for the UHZ1 black hole, with its huge mass, to be formed in that scenario. Therefore, it is speculated that the UHZ1 black hole must have formed from a primordial black hole that triggered the direct collapse of an enormous gas cloud during the high density era of the early universe.

Another unexpected JWST result is that, unlike UHZ1, some of the observed early galaxies that should host supermassive black holes produce no observable x-rays, contrary to expected from galaxies containing massive black holes. Several alternative explanations are being considered: (1) there is no central black hole at all, (2) for reasons unknown, the central black-hole produces no x-ray emission at all, or (3) the black-hole generated x-rays are completely absorbed by surrounding matter before they can escape to free space for observation. Astrophysicists are busily spinning theories, running simulations, and seeking answers.

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The JWST has also revealed that our sky in all directions is full of “little red dots” (LRD), which are the very earliest galaxies of our newly formed universe. These objects were previously invisible to telescopes. That is because they are so far away and consequently moving away so fast that their light has been Doppler-shifted well down into the infrared regime. These LRD seem to be small, red-tinted galaxies that ignited about 600 million years after the Big Bang. They existed for about a billion years thereafter, but in today’s universe, after another 12 billion years or so, there is no remaining trace of them except their ancient light.

As for light emission, their light is actually quite red and not just red-shifted. This suggests that either they emitted mainly red light, or that they contained so much dust that it blocked blue wavelengths, leaving only light at the red end of the electromagnetic spectrum.

They are also quite small in size. Astronomers know that the LRD are tiny, some of them around 100 times smaller than our Milky Way. However, for that size, their observed light output is enormous. This could perhaps be because a large central black hole is producing a boosted light output. However, such a black hole would have to be very large and active indeed to produce the amount of light observed, up to about 40% of the galaxy’s total light output, with the rest coming from its stars. For comparison, our galaxy’s central black hole contributes only 0.01% of its total light output. The black hole explanation, however, is in doubt because black holes produce x-rays, and no x-ray emission has so far been detected from the LRD galaxies. The alternative is that their internal density of stars is much higher than that of the later generations of galaxies like our Milky Way.

To account for the higher light output, that difference in star density would have to be very large. In our solar system, if one draws a sphere with a radius of 4.3 light years centered on our Sun, it would contain only one star, our nearest stellar neighbor Proxima Centauri. But if the density of stars was at the projected LRD level, the same sphere would have to contain about a million stars.

With all of these peculiarities, the LRD are an important new phenomenon that urgently needs explanation and proper description. Their discovery has been compared in importance to the revolutionary discovery of quasars in the 1950s.

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The images of most of the early-universe objects detected by the JWST are just blobs of light a few pixels across. However, a few of these early universe objects lie behind some large foreground galactic mass. In that situation, around the foreground object they may show up as an “Einstein ring” that can gather as much as 10⁶ times more light than direct view from the distant object. Such gravitational lensing and Einstein rings have been observed in a few JWST images that are lensed by the foreground El Gordo cluster of galaxies. Using sophisticated computer correction, astronomers have been able to produce rather well-resolved pictures of several galactic objects as they appeared just 930 million years after the Big Bang.

What they find is that these are not single objects, but rather grape-like clusters of 15 or so individual star-forming clumps. This raises the question of whether this collection of cosmic grape-cluster objects are a chance anomaly, or whether all of the high-red-shift galaxies and LRD of the early universe have the form of dense grape-like clumps. Current galaxy formation simulations have so far not been able to predict any such cluster structures.

So why the clumps? Perhaps in the higher matter density condition of the early universe the rules were different. Dense clumps of hydrogen gas could efficiently and quickly produce stars, these would shine more brightly, and they might form grape-like clumps. Or perhaps something entirely different was going on. Presumably, with the help of the JWST, astronomers can find more early universe objects that can be imaged with gravitational lensing to shed light on this issue. Such work is in progress.

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So that’s a brief summary of some of the impact so far of recent JWST observations. However, there is more to come. The JWST has only been observing for a few years, yet already its observations are creating a major revolution in astrophysics. The JWST will soon be joined by the Nancy Grace Roman Space Telescope, a wide field infrared space telescope in development at NASA and scheduled for launch to a Sun-Earth L2 orbit by May 2027. Like the JWST, it will observe stars and galaxies with infrared light, but with a very wide field of observation, and it will beam down data at the enormous rate of about a terabyte per day.

Further, the European space telescope Euclid, launched last year, will soon precisely determine galactic red shifts. The Vera Rubin Observatory, first light April-May-2025, will photograph the entire visible sky every three days, revolutionizing short-timescale astronomy.

This is an incredibly rich time to study the stars. And theoretical astrophysicists are currently working overtime to understand just what is going on in the early universe

Watch this column for future developments in astrophysics.

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References:

2405. Carniani, et al, “Spectroscopic confirmation of two luminous galaxies at a redshift of 14,” Nature 633, 318-322 (2024); arXiv:2405.18485 [astro-ph.GA].
2406. Natarajan, F. Pacucci, A. Ricarte, Á. Bogdán, A. D. Goulding, and N. Cappelluti, “First Detection of an Overmassive Black Hole Galaxy UHZ1: Evidence for Heavy Black Hole Seed Formation from Direct Collapse,” The Astrophysical Journal Letters 960:L1 (2024); arXiv:2308.02654 [astro-ph.HE].
2407. Feeney, P. Kavanagh, and J. A. Regan, “Searching For JWST’s Little Red Dots,” arXiv:2409.13441 [astro-ph.GA], (2024).
2408. L. Frye, et al, “The JWST PEARLS View of the El Gordo Galaxy Cluster and of the Structure It Magnifies,” The Astrophysical Journal 952:81 (2023); arXiv:2303.03556 [astro-ph.GA]. 

John’s new third hard SF novel, Fermi’s Question, and its prequel, his second hard SF novel Einstein’s Bridge, are available as eBooks from Baen Books at: https://www.baen.com/einstein-s-bridge.html. His first hard SF novel Twistor is available online at:  https://www.amazon.com/Twistor-John-Cramer/dp/048680450X. John’s 2016 nonfiction book describing his transactional interpretation of quantum mechanics, The Quantum Handshake—Entanglement, Nonlocality, and Transactions, (Springer, January 2016) is available online as a hardcover or eBook at: https://www.amazon.com/dp/3319246402. Electronic reprints of “The Alternate View” are currently available online at:  http://www.npl.washington.edu/av.

 

Copyright © 2025 John G. Cramer