Magnetic Field-Decay-Induced Electron Captures: a Strong Heat Source in Magnetar Crusts

Abstract

We propose a new heating mechanism in magnetar crusts. Magnetars' crustal magnetic fields are much stronger than their surface fields; therefore, magnetic pressure partially supports the crust against gravity. The crust loses magnetic pressure support as the field decays and must compensate by increasing the electron degeneracy pressure; the accompanying increase in the electron Fermi energy induces nonequilibrium, exothermic electron captures. The total heat released via field-decay electron captures is comparable to the total magnetic energy in the crust. Thus, field-decay electron captures are an important, if not the primary, mechanism powering magnetars' soft X-ray emission.

4 pages, 2 figures, minor improvements, results and conclusions unchanged; accepted by ApJL

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Cited by in corpus (14)

• Plasma Physics of Extreme Astrophysical Environments
• Magnetars: super(ficially) hot and super(fluid) cool
• Continued Neutron Star Crust Cooling of the 11 Hz X-Ray Pulsar in Terzan 5: A Challenge to Heating and Cooling Models?
• Magneto-Rayleigh-Taylor instability in an elastic finite-width medium overlying an ideal fluid
• Landau level-superfluid modified factor and effective X/$\gamma$-ray coefficient of a magnetar
• The effects of intense magnetic fields on Landau levels in a neutron star
• Thermal emission and magnetic beaming in the radio and X-ray mode-switching PSR B0943+10
• Heating in Magnetar Crusts from Electron Captures
• More than meets the eye: magnetars in disguise
• Onset of Electron Captures and Shallow Heating in Magnetars
• Dynamics of neutrino-driven winds: inclusion of accurate weak interaction rates in strong magnetic fields
• Influence of Magnetic Field Decay on Electron Capture in Magnetars
• Nuclear Criticality as a Contributor to Gamma Ray Burst Events
• Internal Heating in Magnetars: Role of Electron Captures