%0 Generic %1 forconi2023early %A Forconi, Matteo %A Ruchika, %A Melchiorri, Alessandro %A Mena, Olga %A Menci, Nicola %D 2023 %K tifr %T Do the Early Galaxies observed by JWST disagree with Planck's CMB polarization measurements? %U http://arxiv.org/abs/2306.07781 %X 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 $M 10^10.5 M_ødot$ at redshifts of approximately $z10$. This corresponds to a stellar mass density of roughly $\rho_*10^6 M_ødot Mpc^-3$. Despite making conservative assumptions regarding galaxy formation, this finding may not be compatible with the standard $Łambda$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 $Łambda$CDM framework. Assuming a value of $\epsilon=0.2$ for the efficiency of converting baryons into stars, we indeed find that the $Łambda$CDM model is excluded at more than $99.7 \%$ confidence level (C.L.). An even more significant exclusion is found for $0.1$, while a better agreement, but still in tension at more than $95 \%$, is obtained for $=0.32$. 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 $Łambda$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.

@misc{forconi2023early, 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.}, added-at = {2023-06-14T07:53:08.000+0200}, author = {Forconi, Matteo and Ruchika and Melchiorri, Alessandro and Mena, Olga and Menci, Nicola}, biburl = {https://www.bibsonomy.org/bibtex/2ab2525f0642c9686f8361d3adf770d3f/citekhatri}, description = {Do the Early Galaxies observed by JWST disagree with Planck's CMB polarization measurements?}, interhash = {5f706e8cb1261a496e7a9c48d6dde407}, intrahash = {ab2525f0642c9686f8361d3adf770d3f}, keywords = {tifr}, note = {cite arxiv:2306.07781Comment: 5 pages, 2 Figures and a bunch of galaxies}, timestamp = {2023-06-14T07:53:08.000+0200}, title = {Do the Early Galaxies observed by JWST disagree with Planck's CMB polarization measurements?}, url = {http://arxiv.org/abs/2306.07781}, year = 2023 }