Gravitational radiation from neutron stars deformed by crustal Hall drift

Abstract

A precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. Their creation can proceed via crustal Hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined completely to the crust and another which penetrates the whole star. The aim of this study is to explore whether these magnetic structures in the crust can deform the star sufficiently to make it an observable source of gravitational waves. We model the evolution of these field configurations, which can develop, within $\sim 10^4$ -- $10^5$ yr, magnetic spots with local surface field strengths $\sim 10^{14}$ G maintained over $\gtrsim 10^6$ yr. Deformations caused by the magnetic forces are calculated. We show that, under favourable initial conditions, a star undergoing crustal Hall drift can have ellipticity $\epsilon \sim 10^{-6}$, even with sub-magnetar polar field strengths, after $\sim 10^5$ yr. A pulsar rotating at $\sim 10^2$ Hz with such $\epsilon$ is a promising gravitational-wave source candidate. Since such large deformations can be caused only by a particular magnetic field configuration that penetrates the whole star and whose maximum magnetic energy is concentrated in the outer core region, gravitational wave emission observed from radio pulsars can thus inform us about the internal field structures of young neutron stars.

14 pages, 6 figures, 5 tables. Accepted for publication in MNRAS

References in corpus (8)

• Magnetic field dissipation in neutron star crusts: from magnetars to isolated neutron stars
• A new code for the Hall-driven magnetic evolution of neutron stars
• Magnetic Field Evolution in Superconducting Neutron Stars
• Creation of magnetic spots at the neutron star surface
• Magnetic Field Evolution in Neutron Stars: One-Dimensional Multi-Fluid Model
• Neutron star deformation due to poloidal-toroidal magnetic fields of arbitrary multipole order: a new analytic approach
• Simulated magnetic field expulsion in neutron star cores
• Three-dimensional stability of magnetically confined mountains on accreting neutron stars

Cited by in corpus (24)

• All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO and Advanced Virgo O3 data
• Heavy Baryons in Compact Stars
• The Science of the Einstein Telescope
• Magnetic Field Evolution of Neutron Stars I: Basic formalism, numerical techniques, and first results
• Young magnetars with fracturing crusts as fast radio burst repeaters
• Status and perspectives of Continuous Gravitational Wave searches
• Search for Continuous Gravitational Waves from Scorpius X-1 in LIGO O2 Data
• A method to search for long duration gravitational wave transients from isolated neutron stars using the generalized FrequencyHough
• Continuous gravitational wave from magnetized white dwarfs and neutron stars: possible missions for LISA, DECIGO, BBO, ET detectors
• Precursor flares of short gamma-ray bursts from crust yielding due to tidal resonances in coalescing binaries of rotating, magnetized neutron stars
• Asymmetric accretion and thermal `mountains' in magnetized neutron star crusts
• Timescales for detection of super-Chandrasekhar white dwarfs by gravitational wave astronomy
• Magnetic-distortion-induced ellipticity and gravitational wave radiation of neutron stars: millisecond magnetars in short GRBs, Galactic pulsars, and magnetars
• Evolutionary implications of a magnetar interpretation for GLEAM-X J162759.5-523504.3
• Relaxation by thermal conduction of a magnetically confined mountain on an accreting neutron star
• Constraining the ellipticity of new-born magnetar with the observational data of Long gamma-ray bursts
• Evolution of magnetic deformation in neutron star crust
• Premerger phenomena in neutron-star binary coalescences
• The impact of superconductivity and the Hall effect in models of magnetized neutron stars
• Continuous Gravitational Waves and Magnetic Monopole Signatures from Single Neutron Stars
• Measuring spin in coalescing binaries of neutron stars showing double precursors
• Searching for continuous gravitational waves from slowly spinning neutron stars with DECIGO, Big Bang Observer, Einstein Telescope and Cosmic Explorer
• Ernst formulation of axisymmetric fields in $f(R)$ gravity: applications to neutron stars and gravitational waves
• Investigating the neutron star physics through observations of several young pulsars in the dipole-field re-emergence scenario