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Title: Gravitational radiation‐reaction driven instabilities in rotating neutron stars
Abstract

We investigate in this work two different types of instabilities that set limits on the rotation rates of neutron (compact) stars. The first one is that caused by rotation at the Kepler frequency, at which mass shedding at the star's equator sets in. The second limit is set by instabilities driven by the growth of gravitational radiation‐reaction (GRR) driven‐modes of order, which are moderated by shear and bulk viscosity. The calculations are performed for two relativistic models for the nuclear equation of state, DD2 and ACB4. The latter accounts for a phase transition that gives rise to the existence of so‐called mass‐twin compact stars. Our results confirm that the stable rotation periods of cold neutron stars are determined by themodes and that these modes are excited at rotation periods between 1 and 1.4 ms (20–30% above the Kepler periods of these stars). The situation is reversed in hot neutron stars where bulk viscosity damps the GRR modes, pushing the excitation period of the‐mode instability to values below the Kepler period. For cold mass‐twin compact stars, we find that theinstability sets in at rotation periods between 0.8 and 1 ms (25–30% below the Kepler period). This feature may allow one to distinguish conventional neutron stars from their possibly existing mass‐twin counterparts observationally, provided the‐mode instability, which is expected to compete with the‐mode instability, sets the limit on stable rotation of compact stars.

 
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Award ID(s):
2012152 1714068
NSF-PAR ID:
10250429
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Astronomische Nachrichten
Volume:
342
Issue:
5
ISSN:
0004-6337
Page Range / eLocation ID:
p. 799-807
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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