Journal Article

Effect of superfluidity on neutron star oscillations

Hajime Sotani, Ken’ichiro Nakazato, Kei Iida and Kazuhiro Oyamatsu

in Monthly Notices of the Royal Astronomical Society: Letters

Published on behalf of The Royal Astronomical Society

Volume 428, issue 1, pages L21-L25
Published in print January 2013 |
Published online October 2012 | e-ISSN: 1745-3933 | DOI: http://dx.doi.org/10.1093/mnrasl/sls006

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We consider how superfluidity of dripped neutrons in the crust of a neutron star affects the frequencies of the crust's fundamental torsional oscillations. A non-negligible superfluid part of dripped neutrons, which do not comove with nuclei, acts to reduce the enthalpy density and thus enhance the oscillation frequencies. By assuming that the quasi-periodic oscillations observed in giant flares of soft gamma repeaters arise from the fundamental torsional oscillations and that the mass and radius of the neutron star are in the range 1.4 ≤ M/M ≤ 1.8 and 10 ≤ R ≤ 14 km, we constrain the density derivative of the symmetry energy as 100 ≲ L ≲ 130 MeV, which is far more severe than the previous one, L ≳ 50 MeV, derived by ignoring the superfluidity.

Keywords: equation of state; stars: neutron; stars: oscillations

Journal Article.  3678 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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