skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Relativistic tidal properties of neutron stars

Abstract

We study the various linear responses of neutron stars to external relativistic tidal fields. We focus on three different tidal responses, associated to three different tidal coefficients: (i) a gravito-electric-type coefficient G{mu}{sub l}=[length]{sup 2l+1} measuring the lth-order mass multipolar moment GM{sub a{sub 1}}{sub ...a{sub I}} induced in a star by an external lth-order gravito-electric tidal field G{sub a{sub 1}}{sub ...a{sub I}}; (ii) a gravito-magnetic-type coefficient G{sigma}{sub l}=[length]{sup 2l+1} measuring the lth spin multipole moment GS{sub a{sub 1}}{sub ...a{sub I}} induced in a star by an external lth-order gravito-magnetic tidal field H{sub a{sub 1}}{sub ...a{sub I}}; and (iii) a dimensionless 'shape' Love number h{sub l} measuring the distortion of the shape of the surface of a star by an external lth-order gravito-electric tidal field. All the dimensionless tidal coefficients G{mu}{sub l}/R{sup 2l+1}, G{sigma}{sub l}/R{sup 2l+1}, and h{sub l} (where R is the radius of the star) are found to have a strong sensitivity to the value of the star's 'compactness'c{identical_to}GM/(c{sub 0}{sup 2}R) (where we indicate by c{sub 0} the speed of light). In particular, G{mu}{sub l}/R{sup 2l+1}{approx}k{sub l} is found to strongly decrease, as c increases, down to a zero value as c is formally extended to the 'black hole (BH)more » limit'c{sup BH}=1/2. The shape Love number h{sub l} is also found to significantly decrease as c increases, though it does not vanish in the formal limit c{yields}c{sup BH}, but is rather found to agree with the recently determined shape Love numbers of black holes. The formal vanishing of {mu}{sub l} and {sigma}{sub l} as c{yields}c{sup BH} is a consequence of the no-hair properties of black holes. This vanishing suggests, but in no way proves, that the effective action describing the gravitational interactions of black holes may not need to be augmented by nonminimal worldline couplings.« less

Authors:
;  [1];  [2]
  1. Institut des Hautes Etudes Scientifiques, 91440 Bures-sur-Yvette (France)
  2. Italy
Publication Date:
OSTI Identifier:
21325379
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 80; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevD.80.084035; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BLACK HOLES; COUPLING; GRAVITATIONAL FIELDS; GRAVITATIONAL INTERACTIONS; MAGNETIC FIELDS; MASS; NEUTRON STARS; RELATIVISTIC RANGE; SENSITIVITY; SPIN; SURFACES; VELOCITY

Citation Formats

Damour, Thibault, Nagar, Alessandro, and ICRANet, 65122 Pescara. Relativistic tidal properties of neutron stars. United States: N. p., 2009. Web. doi:10.1103/PHYSREVD.80.084035.
Damour, Thibault, Nagar, Alessandro, & ICRANet, 65122 Pescara. Relativistic tidal properties of neutron stars. United States. doi:10.1103/PHYSREVD.80.084035.
Damour, Thibault, Nagar, Alessandro, and ICRANet, 65122 Pescara. Thu . "Relativistic tidal properties of neutron stars". United States. doi:10.1103/PHYSREVD.80.084035.
@article{osti_21325379,
title = {Relativistic tidal properties of neutron stars},
author = {Damour, Thibault and Nagar, Alessandro and ICRANet, 65122 Pescara},
abstractNote = {We study the various linear responses of neutron stars to external relativistic tidal fields. We focus on three different tidal responses, associated to three different tidal coefficients: (i) a gravito-electric-type coefficient G{mu}{sub l}=[length]{sup 2l+1} measuring the lth-order mass multipolar moment GM{sub a{sub 1}}{sub ...a{sub I}} induced in a star by an external lth-order gravito-electric tidal field G{sub a{sub 1}}{sub ...a{sub I}}; (ii) a gravito-magnetic-type coefficient G{sigma}{sub l}=[length]{sup 2l+1} measuring the lth spin multipole moment GS{sub a{sub 1}}{sub ...a{sub I}} induced in a star by an external lth-order gravito-magnetic tidal field H{sub a{sub 1}}{sub ...a{sub I}}; and (iii) a dimensionless 'shape' Love number h{sub l} measuring the distortion of the shape of the surface of a star by an external lth-order gravito-electric tidal field. All the dimensionless tidal coefficients G{mu}{sub l}/R{sup 2l+1}, G{sigma}{sub l}/R{sup 2l+1}, and h{sub l} (where R is the radius of the star) are found to have a strong sensitivity to the value of the star's 'compactness'c{identical_to}GM/(c{sub 0}{sup 2}R) (where we indicate by c{sub 0} the speed of light). In particular, G{mu}{sub l}/R{sup 2l+1}{approx}k{sub l} is found to strongly decrease, as c increases, down to a zero value as c is formally extended to the 'black hole (BH) limit'c{sup BH}=1/2. The shape Love number h{sub l} is also found to significantly decrease as c increases, though it does not vanish in the formal limit c{yields}c{sup BH}, but is rather found to agree with the recently determined shape Love numbers of black holes. The formal vanishing of {mu}{sub l} and {sigma}{sub l} as c{yields}c{sup BH} is a consequence of the no-hair properties of black holes. This vanishing suggests, but in no way proves, that the effective action describing the gravitational interactions of black holes may not need to be augmented by nonminimal worldline couplings.},
doi = {10.1103/PHYSREVD.80.084035},
journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 8,
volume = 80,
place = {United States},
year = {2009},
month = {10}
}