JWST early massive galaxy problem solved?

The inferred masses of galaxies are sensitive to assumptions about their initial mass function (IMF). If we assume all galaxies are basically the same as our Milky Way in terms of the distribution of different types of stars, then the early galaxies identified recently by JWST appear too big to fit with the lamda CDM model of the universe.

However, this key assumption doesn’t really hold true, so if you calculate the masses of these early galaxies based on the expected IMFs in the conditions of the early universe where the galaxies are found (hotter and denser than today), then the masses fit perfectly fine with lamda CDM.

Problem solved? No new physics required?


Seems like there’s three of us having posted this more or less simultaneously.



Links to papers discussed:

Implications of a Temperature-dependent Initial Mass Function. I. Photometric Template Fitting

Preprint: Templates for Fitting Photometry of Ultra-High-Redshift Galaxies

Here is another relevant paper within the past couple of weeks:

Preprint: The most massive Population III stars


Looks like three of us posted this at the same time. :laughing:

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Just watched this which was highly informative wrt discussions we’ve had recently here:

Long story short: The IMF is probably not uniform across time as was just assumed previously, and if the IMF is allowed to vary with temperature, early galaxies discovered with JWST aren’t too massive for ΛCDM.


Some astronomers may consider it solved until they find more distant galaxies. Consider that a prediction.

If and when such galaxies are found, then the models may have to be revised. But it’s useless to revise models based on data that hasn’t been found yet.

Mainstream science: We don’t understand what is going on here. Cool, something to work on!

YEC organization: God of the gaps! We will talk on and on about the problem, but it does not even occur to us to spend the slightest effort to attempt a solution, because filling in gaps spoils apologetics.

Mainstream science: We figured it out at last! We have the data, we have the theory.

YEC organization: We will no longer use that argument. Next problem! That’s how we roll.

YEC never contributes or discovers anything. Remember the fuss over the missing neutrino’s? Zero thanks to YEC for the answer there.

If the solution is actually due to the IMF, that is more than just an explanation for the age of the remote galaxy. A top heavy IMF would be in keeping with a higher primordial gas temperature, as well as low metallicity star formation with allows for masses typically of hundreds or even thousands of solar masses. This is right in line with the big bang model. If you are going to create a universe, this is not a bad way of going about it.


Okay, we will do that if you can be more specific. You predict galaxies will be found more distant than what?

The model is really already revised based on the first images JWST ever took. The conversation is really about scraping the model altogether.

Interestingly, recently watched an AIG livestream where they had astronomers on talking about JWST and Jason Lisle said something about building a cosmology theory, now that he saw some piece of data differently. The words he used to describe it weren’t familiar to me. I don’t think they had to do with JWST. Personally I would like to see a creationist cosmology theory where the CMB is older than galaxy formation because I believe Genesis 1:2 describes unformed matter, as I’ve stated before. But I would be excited to see any creationist cosmology, so I agree with you that someone should attempt a model.

When they do the spectra confirmation on these galaxies and they show low metallicity, please let me know.

The paper in question only covered galaxies in the very first JWST images and had them pegged to around 600-700 million years. I checked the NASA website again and they said JWST could see to 100-250. So I would predict they’d find as massive ones that far. It will take a few years. We’re only at the beginning of this.

As massive as what? The research explained in the video indicates these galaxies actually don’t have unexpectedly large masses if we do not just assume the IMF is the same for all galaxies or for the early universe (which was always a dubious assumption because it probably varies with temperature at least).

True there are lots of observational candidates to verify spectroscopically, and their predicted masses and whether they’re a problem depends on the nature of the IMF. But you’re saying they will detect galaxies galaxies too massive too early? Doesn’t that depend on the nature of the IMF?


How does any scientist “build a theory” without doing extensive hypothesis testing, exactly?

That’s pure cargo-cult pseudoscience.

His use of words that you don’t understand is deliberate design.

Scientific predictions come from clearly stated, mechanistic hypotheses, not from people. Do you have a hypothesis?

To me this reads like a very big problem for this proposed solution of the IMF being different - too many small stars.

I will answer your questions on the prediction @Rumraket - gotta look up a few things and I haven’t made the time…

I could find no such thing entailed by a non-universal IMF explained in that link. How did you extract that view from that pop-sci article?


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I thought this recent Petrov YouTube could be of interest in light of the previous discussion here of early results from JWST of galaxies that appeared at redshifts that allowed very little time for formation after the Big Bang. The YEC community is always eager for any observation that might be trouble for the Big Bang, but they needn’t have much bothered as there was plenty of mainstream buzz about rewriting cosmology. The more prudent were always advising to await spectrographic confirmations, and sure enough, these results align much more comfortably with the Big Bang timeline.

Fair enough - but so far so good for the Big Bang in the era of JWST. A new study, Detection of the cosmological time dilation of high-redshift quasars, found the time dilation for quasar variability to be consistent with the expansion of space.


@RonSewell’s post moved here and comments reopened.

The top heavy Initial Mass Function for the early universe is slowly gaining support.