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29 March 2024 |
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Article overview
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The BAHAMAS project: the CMB--large-scale structure tension and the roles of massive neutrinos and galaxy formation | Ian G. McCarthy
; Simeon Bird
; Joop Schaye
; Joachim Harnois-Deraps
; Andreea S. Font
; Ludovic van Waerbeke
; | Date: |
6 Dec 2017 | Abstract: | Recent studies have presented evidence for tension between the constraints on
Omega_m and sigma_8 from the cosmic microwave background (CMB) and measurements
of large-scale structure (LSS). This tension can potentially be resolved by
appealing to extensions of the standard model of cosmology and/or untreated
systematic errors in the modelling of LSS, of which baryonic physics has been
frequently suggested. We revisit this tension using, for the first time,
carefully-calibrated cosmological hydrodynamical simulations, which thus
capture the back reaction of the baryons on the total matter distribution. We
have extended the BAHAMAS simulations to include a treatment of massive
neutrinos, which currently represents the best motivated extension to the
standard model. We make synthetic thermal Sunyaev-Zel’dovich effect, weak
galaxy lensing, and CMB lensing maps and compare to observed auto- and
cross-power spectra from a wide range of recent observational surveys. We
conclude that: i) in general there is tension between the primary CMB and LSS
when adopting the standard model with minimal neutrino mass; ii) after
calibrating feedback processes to match the gas fractions of clusters, the
remaining uncertainties in the baryonic physics modelling are insufficient to
reconcile this tension; and iii) invoking a non-minimal neutrino mass,
typically of 0.2-0.4 eV (depending on the priors on the other relevant
cosmological parameters and the datasets being modelled), can resolve the
tension. This solution is fully consistent with separate constraints on the
summed neutrino mass from the primary CMB and baryon acoustic oscillations,
given the internal tensions in the Planck primary CMB dataset. | Source: | arXiv, 1712.2411 | Services: | Forum | Review | PDF | Favorites |
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