Reionization during the dark ages from a cosmic axion background

Journal Article · Sun May 01 04:00:00 EDT 2016 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2016/05/006· OSTI ID:22667582

Evoli, Carmelo ^[1]; Leo, Matteo ^[2]; Mirizzi, Alessandro ^[3]; Montanino, Daniele ^[4]

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1. Gran Sasso Science Institute, Viale Francesco Crispi 7, 67100 L'Aquila (Italy)
2. Institute for Particle Physics Phenomenology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
3. Dipartimento Interateneo di Fisica ''Michelangelo Merlin'', Via Amendola 173, 70126 Bari (Italy)
4. Dipartimento di Matematica e Fisica ''Ennio De Giorgi'', Via Arnesano, 73100 Lecce (Italy)

Recently it has been pointed out that a cosmic background of relativistic axion-like particles (ALPs) would be produced by the primordial decays of heavy fields in the post-inflation epoch, contributing to the extra-radiation content in the Universe today. Primordial magnetic fields would trigger conversions of these ALPs into sub-MeV photons during the dark ages. This photon flux would produce an early reionization of the Universe, leaving a significant imprint on the total optical depth to recombination τ. Using the current measurement of τ and the limit on the extra-radiation content Δ N {sub eff} by the Planck experiment we put a strong bound on the ALP-photon conversions. Namely we obtain upper limits on the product of the photon-ALP coupling constant g {sub a} {sub γ} times the magnetic field strength B down to g {sub a} {sub γ} B ∼> 6 × 10{sup −18} GeV{sup −1} nG for ultralight ALPs.

• OSTI ID: 22667582
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 05 Vol. 2016; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AXIONS
COUPLING CONSTANTS
DECAY
GEV RANGE
INFLATIONARY UNIVERSE
MAGNETIC FIELDS
MEV RANGE
PHOTONS
RECOMBINATION
RELATIVISTIC RANGE
UNIVERSE