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Title: Consistent generation of magnetic fields in axion inflation models

Abstract

There has been a growing evidence for the existence of magnetic fields in the extra-galactic regions, while the attempt to associate their origin with the inflationary epoch alone has been found extremely challenging. We therefore take into account the consistent post-inflationary evolution of the magnetic fields that are originated from vacuum fluctuations during inflation. In the model of our interest, the electromagnetic (EM) field is coupled to a pseudo-scalar inflaton φ through the characteristic term φ  F-tilde  F, breaking the conformal invariance. This interaction dynamically breaks the parity and enables a continuous production of only one of the polarization states of the EM field through tachyonic instability. The produced magnetic fields are thus helical. We find that the dominant contribution to the observed magnetic fields in this model comes from the modes that leave the horizon near the end of inflation, further enhanced by the tachyonic instability right after the end of inflation. The EM field is subsequently amplified by parametric resonance during the period of inflaton oscillation. Once the thermal plasma is formed (reheating), the produced helical magnetic fields undergo a turbulent process called inverse cascade, which shifts their peak correlation scales from smaller to larger scales. We consistentlymore » take all these effects into account within the regime where the perturbation of φ is negligible and obtain B{sub eff} ∼ 10{sup −19} G, indicating the necessity of additional mechanisms to accommodate the observations.« less

Authors:
; ;  [1];  [2];  [3]
  1. Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), WPI, TODIAS, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583 (Japan)
  2. Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan)
  3. Department of Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan)
Publication Date:
OSTI Identifier:
22525820
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2015; Journal Issue: 05; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CONFORMAL INVARIANCE; CORRELATIONS; COSMOLOGICAL INFLATION; DISTURBANCES; FLUCTUATIONS; INFLATIONARY UNIVERSE; INFLATONS; MAGNETIC FIELDS; OSCILLATIONS; PARITY; PLASMA; POLARIZATION; SCALARS; TACHYONS

Citation Formats

Fujita, Tomohiro, Namba, Ryo, Tada, Yuichiro, Takeda, Naoyuki, and Tashiro, Hiroyuki. Consistent generation of magnetic fields in axion inflation models. United States: N. p., 2015. Web. doi:10.1088/1475-7516/2015/05/054.
Fujita, Tomohiro, Namba, Ryo, Tada, Yuichiro, Takeda, Naoyuki, & Tashiro, Hiroyuki. Consistent generation of magnetic fields in axion inflation models. United States. doi:10.1088/1475-7516/2015/05/054.
Fujita, Tomohiro, Namba, Ryo, Tada, Yuichiro, Takeda, Naoyuki, and Tashiro, Hiroyuki. Fri . "Consistent generation of magnetic fields in axion inflation models". United States. doi:10.1088/1475-7516/2015/05/054.
@article{osti_22525820,
title = {Consistent generation of magnetic fields in axion inflation models},
author = {Fujita, Tomohiro and Namba, Ryo and Tada, Yuichiro and Takeda, Naoyuki and Tashiro, Hiroyuki},
abstractNote = {There has been a growing evidence for the existence of magnetic fields in the extra-galactic regions, while the attempt to associate their origin with the inflationary epoch alone has been found extremely challenging. We therefore take into account the consistent post-inflationary evolution of the magnetic fields that are originated from vacuum fluctuations during inflation. In the model of our interest, the electromagnetic (EM) field is coupled to a pseudo-scalar inflaton φ through the characteristic term φ  F-tilde  F, breaking the conformal invariance. This interaction dynamically breaks the parity and enables a continuous production of only one of the polarization states of the EM field through tachyonic instability. The produced magnetic fields are thus helical. We find that the dominant contribution to the observed magnetic fields in this model comes from the modes that leave the horizon near the end of inflation, further enhanced by the tachyonic instability right after the end of inflation. The EM field is subsequently amplified by parametric resonance during the period of inflaton oscillation. Once the thermal plasma is formed (reheating), the produced helical magnetic fields undergo a turbulent process called inverse cascade, which shifts their peak correlation scales from smaller to larger scales. We consistently take all these effects into account within the regime where the perturbation of φ is negligible and obtain B{sub eff} ∼ 10{sup −19} G, indicating the necessity of additional mechanisms to accommodate the observations.},
doi = {10.1088/1475-7516/2015/05/054},
journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 05,
volume = 2015,
place = {United States},
year = {2015},
month = {5}
}