Instability Windows and Evolution of Rapidly Rotating Neutron Stars

Mikhail E. Gusakov, Andrey I. Chugunov, and Elena M. Kantor
Phys. Rev. Lett. 112, 151101 – Published 14 April 2014
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Abstract

We consider an instability of rapidly rotating neutron stars in low-mass x-ray binaries (LMXBs) with respect to excitation of r modes (which are analogous to Earth’s Rossby waves controlled by the Coriolis force). We argue that finite temperature effects in the superfluid core of a neutron star lead to a resonance coupling and enhanced damping (and hence stability) of oscillation modes at certain stellar temperatures. Using a simple phenomenological model we demonstrate that neutron stars with high spin frequency may spend a substantial amount of time at these “resonance” temperatures. This finding allows us to explain puzzling observations of hot rapidly rotating neutron stars in LMXBs and to predict a new class of hot, nonaccreting, rapidly rotating neutron stars, some of which may have already been observed and tentatively identified as quiescent LMXB candidates. We also impose a new theoretical limit on the neutron star spin frequency, which can explain the cutoff spin frequency 730Hz, following from the statistical analysis of accreting millisecond x-ray pulsars. In addition to explaining the observations, our model provides a new tool to constrain superdense matter properties by comparing measured and theoretically predicted resonance temperatures.

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  • Received 29 October 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.151101

© 2014 American Physical Society

Authors & Affiliations

Mikhail E. Gusakov1,2, Andrey I. Chugunov1, and Elena M. Kantor1

  • 1Ioffe Institute, Polytekhnicheskaya 26, 194021 St.-Petersburg, Russia
  • 2St.-Petersburg State Polytechnical University, Polytekhnicheskaya 29, 195251 St.-Petersburg, Russia

See Also

Explaining observations of rapidly rotating neutron stars in low-mass x-ray binaries

Mikhail E. Gusakov, Andrey I. Chugunov, and Elena M. Kantor
Phys. Rev. D 90, 063001 (2014)

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Issue

Vol. 112, Iss. 15 — 18 April 2014

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