Generation of the magnetic helicity in a neutron star driven by the electroweak electron-nucleon interaction

Abstract

We study the instability of magnetic fields in a neutron star core driven by the parity violating part of the electron-nucleon interaction in the Standard Model. Assuming a seed field of the order $10^{12}\text{G}$, that is a common value for pulsars, one obtains its amplification due to such a novel mechanism by about five orders of magnitude, up to $10^{17}\text{G}$, at time scales $\sim (10^3-10^5)\text{yr}$. This effect is suggested to be a possible explanation of the origin of the strongest magnetic fields observed in magnetars. The growth of a seed magnetic field energy density is stipulated by the corresponding growth of the magnetic helicity density due to the presence of the anomalous electric current in the Maxwell equation. Such an anomaly is the sum of the two competitive effects: (i) the chiral magnetic effect driven by the difference of chemical potentials for the right and left handed massless electrons and (ii) constant chiral electroweak electron-nucleon interaction term, which has the polarization origin and depends on the constant neutron density in a neutron star core. The remarkable issue for the decisive role of the magnetic helicity evolution in the suggested mechanism is the arbitrariness of an initial magnetic helicity including the case of non-helical fields from the beginning. The tendency of the magnetic helicity density to the maximal helicity case at large evolution times provides the growth of a seed magnetic field to the strongest magnetic fields in astrophysics.

17 pages in JCAP LaTeX style, 10 esp figures, paper is significantly revised, several new references are added, multiple misprints are corrected, version to be published in JCAP

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Cited by in corpus (9)

• Chiral effects in astrophysics and cosmology
• Holographic approach to compact stars and their binary mergers
• Equilibration of the chiral asymmetry due to finite electron mass in electron-positron plasma
• Galvano-rotational effect induced by electroweak interactions in pulsars
• Chiral anomaly and dynamos from inhomogeneous chemical potential fluctuations
• Relaxation of the chiral chemical potential in the dense matter of a neutron star
• Efficiency of dynamos from an autonomous generation of chiral asymmetry
• Magnetic helicity in rotating neutron stars
• Relaxation of the chiral imbalance in dense matter of a neutron star