Inefficiency of chiral dynamos in protoneutron stars and the early universe

Abstract

The chiral plasma instability (CPI) has been invoked as a possible mechanism for generating primordial magnetic fields in the universe and ultrastrong fields in neutron stars. We investigate chiral dynamos where the chirality imbalance is pumped by a source on a timescale $t_0$ and show that the CPI rate $\gamma$ is limited to ${\gamma }_0/(1+{\mathcal{Q}}^2)$, where $\mathcal{Q}=({\gamma }_0{t}_0{)}^{1/3}$ and ${\gamma }_0$ corresponds to models with instantaneously created chirality imbalance $(t_0=0)$. We then find that chiral flipping with rate ${\Gamma }_{\mathrm{f}}$ hinders the chiral dynamo if ${\Gamma }_{\mathrm{f}}>{\gamma }_0/(1+{\mathcal{Q}}^2)$ and completely suppresses it if ${\Gamma }_{\mathrm{f}}>{\gamma }_0/(1+{\mathcal{Q}}^{3/2})$. Realistic $t_0$ typically give $\mathcal{Q}\gg 1$, which makes the dynamo greatly vulnerable to suppression by chiral flipping. The suppression is strong in protoneutron stars and may be (barely) avoided near the electroweak transition in the early universe.

References in corpus (10)

• The turbulent chiral-magnetic cascade in the early universe
• The Role of the Electron Mass in Damping Chiral Magnetic Instability in Supernova and Neutron Stars
• Magnetic Field Generation in Stars
• Chiral effects in astrophysics and cosmology
• Origin of neutron star magnetic fields
• Reconnection-controlled decay of magnetohydrodynamic turbulence and the role of invariants
• Evolution of the Primordial Axial Charge across Cosmic Times
• Chiral plasma instability and inverse cascade from nonequilibrium left-handed neutrinos in core-collapse supernovae
• Production of a chiral magnetic anomaly with emerging turbulence and mean-field dynamo action
• Chiral effects and Joule heating in hot and dense matter