One of the most significant benefits of the James Webb Space Telescope (JWST) is its unique ability to detect and measure galaxies within an era known as “the cosmic dawn.” For astronomers, the name has nothing to do with the sci-fi thriller about a UFO cult. Rather, it refers to the period from 0.2 to 1.2 billion years after the cosmic origin event, the era when starlight first illuminated the universe. JWST images of this era have caused some people to doubt the credibility of big bang cosmology.  

Surprising Observations
The initial JWST deep field images revealed an unexpected abundance of bright galaxies, considered as candidates to be at redshifts greater than 10,1 distances that correspond with the first 0.478 billion years of cosmic history.2 To date, the JWST has detected as many as 90 such candidates—a number significantly higher than what standard big bang creation models would predict. 

By “standard” big bang models, I mean a set of models characterized by a flat cosmic geometry and in which dark energy is the most dominant component of the universe, with cold dark matter as the second most dominant component. Thus, they are also referred to as ΛCDM big bang models (with L standing for dark energy and CDM for cold dark matter). The JWST images revealed not only an unanticipated abundance of bright cosmic dawn galaxy candidates, but also that these candidates’ ultraviolet luminosities appear about ten times brighter than the ΛCDM models had predicted. 

This surprising overabundance of cosmic dawn galaxy candidates with exceptionally high ultraviolet luminosities quickly gave rise to a spate of popular articles claiming that big bang cosmology needs major revision. Some astronomers began calling for “a reexamination of the theoretical landscape of galaxy formation at the cosmic dawn.”3 A few have gone so far as to claim that physics beyond standard ΛCDM cosmology must now be considered. Examples of proposed new options include “a modified primordial power spectrum,”4 a “primordial non-Gaussian” cosmos,”5 or “alternative dark matter models.”6 However, these “new physics” hypotheses do not represent alternatives to big bang cosmology. They are still big bang origin models, even though they are not ΛCDM big bang models.

A more extreme response has come from creationist organizations that espouse belief in a universe and/or Earth only thousands of years old. These groups are claiming that the JWST images refute big bang cosmology entirely. For example, the founder of Answers in Genesis writes, “JWST’s images are blatantly and repeatedly contradicting the Big Bang Hypothesis.”7 In a more recent article, a staff physicist at the Institute for Creation Research has written, “By Big Bang reckoning, . . . these [early] galaxies should appear very ‘unevolved’ and ‘immature.’ Yet, this expectation is routinely contradicted, and data from the JWST are making the disagreement even worse.”8

Most astronomers favor other explanations for the JWST’s glimpse into the early moments of the cosmic dawn. Any one or combination of these proposed explanations appears feasible: (1) a higher star formation efficiency at that time; (2) a higher percentage of very massive stars at that time; (3) a reduced quantity of dust or the presence of dust with a less dimming effect; and (4) adjustments to our understanding of the properties of dark matter haloes at that time. 

I am glad to report that spectroscopic follow-up studies for the observed galaxy candidates are ongoing. As research continues, the list of 90 ultrabright galaxies initially thought to have formed early in the cosmic dawn will likely be reduced.

A More Promising Resolution
As astronomers continue to consider the significance of the JWST observations, a team of six astronomers at five American universities applied a novel approach to the investigation. Previously, these researchers applied a computer simulation tool, called the Feedback in Realistic Environments (FIRE) to show that ΛCDM big bang models successfully predicted the observed properties of galaxies that formed during the most recent 13 billion years of cosmic history. They used the same FIRE computer simulation to test how well different cosmic models match the properties observed by the JWST of bright cosmic dawn galaxy candidates, specifically to those seen at lookback times ranging from 13.1–13.5 billion years ago.9 These lookback times correspond to the universe when it was a mere 0.3–0.7 billion years old. 

The team first pointed out that the claim in the context of ΛCDM big bang models of an “overabundance” of bright galaxy candidates with exceptionally high ultraviolet luminosities in the cosmic dawn era reflected a potentially false assumption: that the star formation rate in these galaxies was constant. The team then tested two models for these cosmic dawn galaxies, one in which the star formation rate remains constant during the first 0.7 billion years of cosmic history, and the other in which star formation occurs in bursts, separated by brief intervals. 

The latter of the two models corresponds closely with what astronomers have directly observed for galaxies throughout the past 13 billion years. Also, previous FIRE computer simulations based on the intermittent burst model produced the best fit with observed galaxy properties during the past 13 billion years. 

The FIRE computer simulations that presumed cosmic dawn galaxies, those forming in the first 0.3–0.7 billion years of cosmic history, experienced stochastic, or “bursty,” star formation episodes, yielded ultraviolet galaxy luminosities about ten times brighter than simulations presuming star formation at a constant rate. The team found that with star formation occurring in bursts within these galaxies/galaxy candidates, no need existed to invoke nonstandard big bang models, such as a top-heavy initial stellar mass function, reduced dust attenuation, alternate dark matter halo properties, or strongly enhanced star formation efficiency. The team concluded that JWST observations of early cosmic dawn galaxies appears to have yielded more, not less, evidence for LCDM big bang models.

Philosophical Implications
The team’s conclusions are consistent with reports presented in the Stars, Cells, and God podcast episode on the “Source of Heavy Elements.”10 They’re also aligned with two previous articles I have posted on JWST observations relevant to big bang cosmology.11 Thanks to the computer modeling and analysis by this team of astronomers, we have gained even more confidence that the latest JWST observations support the biblically described cosmic creation event, aka the big bang.12    

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Endnotes

1. C. T. Donnan et al., “The Evolution of the Galaxy UV Luminosity Function at Redshifts z = 8–15 from Deep JWST and Ground-Based Near-Infrared Imaging,” Monthly Notices of the Royal Astronomical Society 518, no. 4 (February 2023): 6011–6040, doi:10.1093/mnras/stac3472; Yuichi Harikane et al., “A Comprehensive Study of Galaxies at z ~ 9–16 Found in the Early JWST Data: Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-Reionization Epoch,” Astrophysical Journal Supplement 265, no. 1 (March 2023): id. 5, doi:10.3847/1538-4365/acaaa9; Haojing Yan et al., “First Batch of z = 11–20 Candidate Objects Revealed by the James Webb Space Telescope Early Release Observations on SMACS 0723-73,” Astrophysical Journal Letters 942, no. 1 (January 1, 2023): id. L9, doi:10.3847/2041-8213/aca80c.
2. Edward L. Wright, “A Cosmology Calculator for the World Wide Web,” Publications of the Astronomical Society of the Pacific 118, no. 850 (December 13, 2006): 1711–1715, doi:10.1086/510102. The online calculator is at https://www.astro.ucla.edu/~wright/CosmoCalc.html.
3. Guochao Sun et al., “Bursty Star Formation Naturally Explains the Abundance of Bright Galaxies at Cosmic Dawn,” Astrophysical Journal Letters 955, no. 2 (October 1, 2023): id. L35, p. 1, doi:10.3847/2042-8213/acf85a.
4. Hamsa Padmanabhan and Abraham Loeb, “Alleviating the Need for Exponential Evolution of JWST Galaxies at 1010MSun Haloes at z > 10 by a Modified LCDM Power Spectrum,” Astrophysical Journal Letters 953, no. 1 (August 10, 2023): id. L4, doi:10.3847/2042-8213/acea7a; Priyank Parashari and Ranjan Laha, “Primordial Power Spectrum in Light of JWST Observations of High Redshift Galaxies,” Monthly Notices of the Royal Astronomical Society: Letters526, no. 1 (November 2023): L63–L69, doi:10.1093/mnras/slad107.
5. Matteo Biagetti, Gabriele Franciolini, and Antonio Riotto, “High-Redshift JWST Observations and Primordial Non-Gaussianity,” Astrophysical Journal 944, no. 2 (February 16, 2023): id. 113, doi:10.3847/1538-4357/acb5ea.
6. Yan Gong et al., “Fuzzy Dark Matter as a Solution to Reconcile the Stellar Mass Density of High-z Massive Galaxies and Reionization History,” Astrophysical Journal 947, no. 1 (April 17, 2023): if. 28, doi:10.3847/1538-4357/acc109.
7. Ken Ham, “Does the James Webb Space Telescope Show the Big Bang Didn’t Happen?,” Answers in Genesis, Ken Ham Blog, August 22, 2022.
8. Jake Hebert, “Webb Telescope Continues to Challenge Big Bang,” Institute for Creation Research, News: Creation Science Update, January 26, 2023.
9. Sun et al., “Bursty Star Formation Naturally Explains the Abundance of Bright Galaxies at Cosmic Dawn.” 
10. Fazale Rana and Hugh Ross, “Neanderthal Flower Burial Nixed and Source of Heavy Elements,” Reasons to Believe podcast, Stars, Cells, and God (November 29, 2023), https://www.youtube.com/watch?v=Y3yKYEnKQGw.
11. Hugh Ross, “Cosmic Dawn Evidence Bolsters Case for Creation,” Today’s New Reason to Believe (blog), Reasons to Believe, July 10, 2023; Hugh Ross, “James Webb Space Telescope: Initial Revelations,” Today’s New Reason to Believe (blog), Reasons to Believe, September 12, 2022.
12. Hugh Ross, “What Does the Bible Say about the Big Bang?” Today’s New Reason to Believe (blog), Reasons to Believe, February 6, 2023.