A comparison of the Rh=ct and Λ CDM cosmologies based on the observed halo mass function
AffiliationUniv Arizona, Dept Phys
Univ Arizona, Program Appl Math, Dept Phys
Univ Arizona, Dept Astron
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CitationYennapureddy, M.K. & Melia, F. Eur. Phys. J. C (2019) 79: 571. https://doi.org/10.1140/epjc/s10052-019-7082-z
JournalEUROPEAN PHYSICAL JOURNAL C
RightsCopyright © The Author(s) 2019. EPJC is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractThe growth of structure may be traced via the redshift-dependent halo mass function. This quantity probes the re-ionization history and quasar abundance in the Universe, constituting an important probe of the cosmological predictions. Halos are not directly observable, however, so their mass and evolution must be inferred indirectly. The most common approach is to presume a relationship with galaxies and halos. Studies based on the assumption of a constant halo to stellar mass ratio Mh/M (extrapolated from z less than or similar to 4) reveal significant tension with Lambda CDM - a failure known as The Impossibly Early Galaxy Problem. But whether this ratio evolves or remains constant through redshift 4 less than or similar to z less than or similar to 10 is still being debated. To eliminate the tension with Lambda CDM, it would have to change by about 0.8 dex over this range, an issue that may be settled by upcoming observations with the James Webb Space Telescope. In this paper, we explore the possibility that this major inconsistency may instead be an indication that the cosmological model is not completely correct. We study this problem in the context of another Friedmann-Lemaitre-Robertson-Walker (FLRW) model known as the Rh=ct universe, and use our previous measurement of sigma 8 from the cosmological growth rate, together with new solutions to the Einstein-Boltzmann equations, to interpret these recent halo measurements. We demonstrate that the predicted mass and redshift dependence of the halo distribution in Rh=ct is consistent with the data, even assuming a constant Mh/M throughout the observed redshift range (4 less than or similar to z less than or similar to 10), contrasting sharply with the tension in Lambda CDM. We conclude that - if Mh/M turns out to be constant - the massive galaxies and their halos must have formed earlier than is possible in Lambda CDM.
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