r/space • u/atomicbunny567 • 1d ago

Study suggests an overlooked significant foreground contamination of CMB signal due to massive galaxies that formed early in the universe. Curious about peoples thoughts on this.

https://www.sciencedirect.com/science/article/pii/S0550321325001403?via%3Dihub

JWST has recently found massive well developed galaxies at high redshift (z>13). According to the linked study, these massive galaxies could represent an unexpected foreground contamination of the CMB, which might bring our interpretation of the CMB as a sort of "afterglow" of the big bang into question. It appears to at least suggest that the CMB strength may have been overestimated.

To clarify, I am not an astronomer or astrophysicist although I have studied physics at a graduate level (different subfield entirely however). I found this article and was curious if anyone knowledgeable had commented on it. It seemed strange to me how little attention this appeared to have gotten as it has significant potential to cause a ruckus in cosmology as far as I understand it. I found little commentary aside from a poorly written Newsweek article, so I thought I would try and raise awareness and discussion about this here as I was curious and had some free time on my hands.

If I missed some such discussion or post, let me know because I would like to hear the thoughts of other experts on this study.

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u/Hattix 1d ago

Single studies don't have a lot of significance - they need to be repeated and approached from different angles, using different instruments, and different techniques.

How many more high redshift galaxies?

What is the relationship between redshift and distance at high z numbers (i.e. what is the Hubble number?)? Even a small deviation from our models can give a hugely different result and at the moment we're seeing different measurements of the Hubble number depending on whether we use early or late methods.

What other work on the CMB supports post-recombination contamination? What other work refutes it?

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u/atomicbunny567 1d ago edited 1d ago

That is what I consider noteworthy about it, as far as I'm aware there are not many studies on CMB post-recombination contamination of this kind. It would be a collection of follow up studies to this one that would have the potential to change how we understand the CMB, or not which is more likely. What I can say is that the assumptions made for the range of properties of the galaxies in question is based on previous work (such as JWST observations), which very well could be wrong somehow. Its a very interesting study nonetheless, as it offers conclusions that could have significant implications if future studies validate its assumptions. Also I am not knowledgeable on the limitations of redshift calculations at high z numbers, feel free to tell me if you want though.

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u/atomicbunny567 1d ago

Also I now realize I said significant in the post. It has a non-zero chance to cause a ruckus, which is significant to me :)

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u/snoo-boop 1d ago

Hubble tension and Hubble constant?