Formulating the r-mode Problem for Slowly Rotating Neutron Stars

Andersson, Nils; Gittins, Fabian

doi:10.3847/1538-4357/acbc1e

Formulating the r-mode Problem for Slowly Rotating Neutron Stars

Journal Article · Wed Mar 15 00:00:00 EDT 2023 · The Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/acbc1e· OSTI ID:2418909

Andersson, Nils ^[1]; Gittins, Fabian ^[2]

Univ. of Southampton (United Kingdom); University of Southampton (United Kingdom)
Univ. of Southampton (United Kingdom)

We revisit the problem of inertial r-modes in stratified stars, drawing on a more precise description of the composition stratification in a mature neutron star. The results highlight issues with the traditional approach to the problem, leading us to rethink the computational strategy for the r-modes of nonbarotropic neutron stars. We outline two strategies for dealing with the problem. For moderate to slowly rotating neutron stars the only viable alternative may be to approach the problem numerically from the outset, while a meaningful slow-rotation calculation can be carried out for the fastest known spinning stars (which may be close to being driven unstable by the emission of gravitational waves). We demonstrate that the latter approach leads to a problem close, but not identical, to that for barotropic inertial modes. We also suggest that these reformulations of the problem likely resolve the long-standing problem of singular behavior associated with a corotation point in rotating relativistic neutron stars. This issue needs to be resolved in order to guide future gravitational-wave searches.

View Accepted Manuscript (DOE)

Research Organization:: Univ. of Washington, Seattle, WA (United States)

Sponsoring Organization:: National Science Foundation (NSF); Science and Technology Facilities Council (STFC); USDOE Office of Science (SC)

Grant/Contract Number:: FG02-00ER41132

OSTI ID:: 2418909

Journal Information:: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 2 Vol. 945; ISSN 0004-637X

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United States

Language:: English

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