Open AccessNon‐linear r modes in neutron stars: a hydrodynamical limitation on r ‐mode amplitudes
Author(s) -
Lin LapMing,
Suen WaiMo
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10536.x
Subject(s) - physics , polytropic process , amplitude , dimensionless quantity , neutron star , instability , coupling (piping) , mode (computer interface) , equation of state , mode coupling , astrophysics , polytrope , quantum electrodynamics , mechanics , classical mechanics , quantum mechanics , mechanical engineering , computer science , engineering , operating system
Previously, we found that large‐amplitude r modes could decay catastrophically due to non‐linear hydrodynamic effects. In this paper, we found the particular coupling mechanism responsible for this catastrophic decay, and identified the fluid modes involved. We find that for a neutron star described by a polytropic equation of state with polytropic index Γ= 2, the coupling strength of the particular three‐mode interaction causing the decay is strong enough that the usual picture of the r ‐mode instability with a flow pattern dominated by that of an r mode can only be valid for the dimensionless r ‐mode amplitude less than O (10 −2 ).