Effects Of Neutron Star Research Articles

The Meissner effect in neutron stars

Abstract We present the first model aimed at understanding how the Meissner effect in a young neutron star affects its macroscopic magnetic field. In this model, field expulsion occurs on a dynamical timescale, and is realised through two processes that occur at the onset of superconductivity: fluid motions causing the dragging of field lines, followed by magnetic reconnection. Focussing on magnetic fields weaker than the superconducting critical field, we show that complete Meissner expulsion is but one of four possible generic scenarios for the magnetic-field geometry, and can never expel magnetic flux from the centre of the star. Reconnection causes the release of up to ∼5 × 1046 erg of energy at the onset of superconductivity, and is only possible for certain favourable early-phase dynamics and for pre-condensation fields 1012 G ≲ B ≲ 5 × 1014 G. Fields weaker or stronger than this are predicted to thread the whole star.

Permanent mean spin source of the chiral magnetic effect in neutron stars

We suggest the generalization of the Anomalous Magneto-Hydro-Dynamics (AMHD) in the chiral plasma of a neutron star (NS) accounting for the mean spin in the ultrarelativistic degenerate electron gas within the magnetized NS core as a continuing source of the chiral magnetic effect. Using the mean field dynamo model generalized in AMHD, one can obtain the growth of a seed magnetic field up to 1018 G for an old non-superfluid NS at its neutrino cooling era t < 106 yr, while neglecting any matter turbulence within its core and assuming the rigid NS rotation. The application of the suggested approach to the evolution of magnetic fields observed in magnetars, B∼ 1015 G, should be self-consistent with all approximations used in the suggested laminar dynamo, at least, up to the jumps of growing fields.

Gravitomagnetic effect in magnetized neutron stars

Rotating bodies in General Relativity produce frame dragging, also known as the gravitomagnetic effect in analogy with classical electromagnetism. In this work, we study the effect of magnetic field on the gravitomagnetic effect in neutron stars with poloidal geometry, which is produced as a result of its rotation. We show that the magnetic field has a non-negligible impact on frame dragging. The maximum effect of the magnetic field appears along the polar direction, where the frame-dragging frequency decreases with increase in magnetic field, and along the equatorial direction, where its magnitude increases. For intermediate angles, the effect of the magnetic field decreases, and goes through a minimum for a particular angular value at which magnetic field has no effect on gravitomagnetism. Beyond that particular angle gravitomagnetic effect increases with increasing magnetic field. We try to identify this `null region' for the case of magnetized neutron stars, both inside and outside, as a function of the magnetic field, and suggest a thought experiment to find the null region of a particular pulsar using the frame dragging effect.

Magnetorotational evolution of isolated neutron stars

Abstract We consider a decay of the magnetic field, originally confined to a moderately deep layer of the neutron star crust with the density ρ ≲ 4 · 1011 g/cm3. The effect of neutron star cooling on the conductivity and the rate of the magnetic field dissipation is taken into account. The main goal of this paper is the investigation of the influence of the field decay on the neutron star spinning down in the magnetic dipole braking model. Evolutionary tracks of pulsars on the B s – P diagram, where B s is the magnetic field at the surface and P is the spin period, have been calculated. It is shown that the crustal decay model is in a qualitative agreement with observational data if a significant fraction of the outer crust was originally occupied by the magnetic field.

Catalyzed nucleon decay in neutron stars

We consider the effect in neutron stars of nucleon decay catalyzed by grand unified monopoles. Invoking observational limits on the diffuse ultraviolet and X-ray background, we obtain a bound on the product of the cross section σ for the catalysis process and the interstellar monopole flux Φ, 〈 σβ〉 Φ ⪅ 10 −27cm 2 × 10 −25cm −2s −1sr −1. If, as Rubakov and Callan have recently suggested, 〈σβ〉 is a typical strong interaction cross section, then this bound is stronger by nine orders of magnitude than previous limits on the monopole flux.

Crystalline nuclei and the Pomeranchuk effect in neutron stars

The transition from the liquid to the crystalline phase upon adiabatic compression of the core of a neutron star during its ''birth'' leads to a sharp cooling of the crystalline neutron core. A similar problem was considered previously for liquid He/sup 3/ by I. Ya. Pomeranchuk. The effect strongly influences the character of neutron star cooling curves. Upon further evolution of the star either fusion of the crystalline nucleus or further crystallization of the neutron liquid is possible. In both cases radial stresses develop in the star, as a consequence of which ''starquakes'' are possible.

Battery Effect in Neutron Stars

RECENTLY there has been interest in the problem of intense magnetic fields in gravitationally collapsed bodies1,2; in particular the radio emission from neutron stars (pulsars) suggests strong magnetic fields of the order of 1012 G (refs. 1, 3 and 4). The battery effect for nonuniformly rotating early main sequence stars has been considered recently5,6, but we will show in this communication that there is a possible battery effect in neutron stars which has a different physical cause.