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Do the Early Galaxies observed by JWST disagree with Planck's CMB polarization measurements?

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arxiv 2306.07781 v2 pith:6OZH37OT submitted 2023-06-13 astro-ph.CO hep-ph

classification astro-ph.COhep-ph
keywords planckjwstlambdaagreementbetterepsilonobservationscompatible
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abstract

The recent observations from the James Webb Space Telescope have led to a surprising discovery of a significant density of massive galaxies with masses of $M \ge 10^{10.5} M_{\odot}$ at redshifts of approximately $z\sim 10$. This corresponds to a stellar mass density of roughly $\rho_*\sim 10^6 M_{\odot} Mpc^{-3}$. Despite making conservative assumptions regarding galaxy formation, this finding may not be compatible with the standard $\Lambda$CDM cosmology that is favored by observations of CMB Anisotropies from the Planck satellite. In this paper, we confirm the substantial discrepancy with Planck's results within the $\Lambda$CDM framework. Assuming a value of $\epsilon=0.2$ for the efficiency of converting baryons into stars, we indeed find that the $\Lambda$CDM model is excluded at more than $99.7 \%$ confidence level (C.L.). An even more significant exclusion is found for $\epsilon \sim 0.1$, while a better agreement, but still in tension at more than $95 \%$, is obtained for $\epsilon =0.32$. This tension, as already discussed in the literature, could arise either from systematics in the JWST measurements or from new physics. Here, as a last-ditch effort, we point out that disregarding the large angular scale polarization obtained by Planck, which allows for significantly larger values of the matter clustering parameter $\sigma_8$, could lead to better agreement between Planck and JWST within the $\Lambda$CDM framework. Interestingly, the model compatible with Planck temperature-only data and JWST observation also favors a higher Hubble constant $H_0=69.0\pm1.1$ km/s/Mpc at $68\%$ C.L., in better agreement with observations based on SN-Ia luminosity distances.

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Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Dark Secrets of Baryons: Illuminating Dark Matter-Baryon Interactions with JWST

    hep-ph 2025-11 conditional novelty 5.0 of 10

    JWST ultraviolet luminosity function data currently provide the strongest upper limits on velocity-dependent (∝v^{-2}) dark matter–proton scattering for sub-GeV dark matter.

  2. Illustrating the consequences of a misuse of $\sigma_8$ in cosmology

    astro-ph.CO 2025-01 accept novelty 5.0 of 10

    Cosmologists should compare clustering amplitude with the h-independent statistic sigma_12 instead of sigma_8, because sigma_8's smoothing scale shifts with H0 and artificially worsens the growth tension in high-H0 models.

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