The early-science observations made by the James Webb Space Telescope (JWST) have revealed an excess of ultramassive galaxy candidates that appear to challenge the standard cosmological model (ΛCDM). Here, we argue that any modifications to ΛCDM that can produce such ultramassive galaxies in the early Universe would also affect the UV galaxy luminosity function (UV LF) inferred from the Hubble Space Telescope (HST). The UV LF covers the same redshifts (z≈7-10) and host-halo masses (M_{h}≈10^{10}-10^{12}M_{⊙}) as the JWST candidates, but tracks star-formation rate rather than stellar mass. We consider beyond-ΛCDM power-spectrum enhancements and show that any departure large enough to reproduce the abundance of ultramassive JWST candidates is in conflict with the HST data. Our analysis, therefore, severely disfavors a cosmological explanation for the JWST abundance problem. Looking ahead, we determine the maximum allowable stellar-mass function and provide projections for the high-z UV LF given our constraints on cosmology from current HST data.
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http://dx.doi.org/10.1103/PhysRevLett.132.061002 | DOI Listing |
Nature
November 2024
School of Physics, University of Melbourne, Parkville, Victoria, Australia.
Phys Rev Lett
February 2024
William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA.
The early-science observations made by the James Webb Space Telescope (JWST) have revealed an excess of ultramassive galaxy candidates that appear to challenge the standard cosmological model (ΛCDM). Here, we argue that any modifications to ΛCDM that can produce such ultramassive galaxies in the early Universe would also affect the UV galaxy luminosity function (UV LF) inferred from the Hubble Space Telescope (HST). The UV LF covers the same redshifts (z≈7-10) and host-halo masses (M_{h}≈10^{10}-10^{12}M_{⊙}) as the JWST candidates, but tracks star-formation rate rather than stellar mass.
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