Magnetar birth: rotation rates and gravitational-wave emission

Lander, S. K. and Jones, D. (2020) Magnetar birth: rotation rates and gravitational-wave emission. Monthly Notices of the Royal Astronomical Society, 494 (4). pp. 4838-4847. ISSN 0035-8711

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Abstract

Understanding the evolution of the angle chi between a magnetar's rotation and magnetic axes sheds light on the star's birth properties. This evolution is coupled with that of the stellar rotation Omega, and depends on the competing effects of internal viscous dissipation and external torques. We study this coupled evolution for a model magnetar with a strong internal toroidal field, extending previous work by modelling - for the first time in this context - the strong protomagnetar wind acting shortly after birth. We also account for the effect of buoyancy forces on viscous dissipation at late times. Typically, we find that chi -> 90 degrees shortly after birth, then decreases towards 0 degrees over hundreds of years. From observational indications that magnetars typically have small chi, we infer that these stars are subject to a stronger average exterior torque than radio pulsars, and that they were born spinning faster than similar to 100-300 Hz. Our results allow us to make quantitative predictions for the gravitational and electromagnetic signals from a newborn rotatingmagnetar. We also comment briefly on the possible connection with periodic fast radio burst sources.

Item Type: Article
Uncontrolled Keywords: stars: evolution,stars: interiors,stars: magnetic field,stars: neutron,stars: rotation,polarized radio-emission,soft gamma-repeaters,magnetorotational instability,spin-down,evolution,pulsars,braking,fields,winds,population
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Depositing User: LivePure Connector
Date Deposited: 30 Jun 2020 00:20
Last Modified: 13 Jul 2020 00:00
URI: https://ueaeprints.uea.ac.uk/id/eprint/75823
DOI: 10.1093/mnras/staa966

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