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Relieving the Hubble Tension with Primordial Magnetic Fields
Karsten Jedamzik1, Levon Pogosian2,3
1Laboratoire de Univers et Particules de Montpellier, UMR5299-CNRS, Universite de Montpellier, 34095 Montpellier, France.
Physical Review Letters
|November 16, 2020
Summary
Primordial magnetic fields may resolve cosmological tensions. Accounting for baryon density inhomogeneities, induced by these fields, reconciles the Hubble constant and matter density measurements from Planck and supernovae data.
Area of Science:
- Cosmology
- Astrophysics
- Particle Physics
Background:
- Cosmic Microwave Background (CMB) measurements from Planck indicate a Hubble constant (H₀) significantly lower than that from Type Ia supernovae.
- The standard cosmological model, when fitted to Planck data, predicts higher matter density (Ωm) and clustering amplitude (S₈) than observed in Dark Energy Survey Year 1 data.
- These discrepancies, known as the H₀ and S₈-Ωm tensions, challenge the current understanding of the universe.
Purpose of the Study:
- To investigate whether enhanced recombination rates due to small-scale baryon density inhomogeneities can resolve the H₀ and S₈-Ωm tensions.
- To explore the role of primordial magnetic fields in inducing these baryon inhomogeneities.
- To determine if the magnetic field strength required to resolve cosmological tensions is consistent with observed astrophysical magnetic fields.
Main Methods:
- Incorporating an enhanced recombination rate into cosmological models.
- Analyzing the impact of baryon density inhomogeneities on CMB and large-scale structure observables.
- Comparing model predictions with observational data from Planck, Type Ia supernovae, and the Dark Energy Survey.
Main Results:
- Accounting for enhanced recombination rates due to baryon inhomogeneities successfully resolves both the H₀ and S₈-Ωm tensions.
- The required baryon inhomogeneities can be generated by primordial magnetic fields present before recombination.
- The magnetic field strength needed to resolve these tensions aligns with values required to explain galactic, cluster, and extragalactic magnetic fields without dynamo amplification.
Conclusions:
- Primordial magnetic fields offer a compelling solution to major cosmological tensions.
- The proposed mechanism provides a unified explanation for both H₀ and S₈-Ωm discrepancies.
- Further research into primordial magnetic fields is warranted, with specific observational targets identified.
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