Bounds on neutron-star moments of inertia and the evidence for general relativistic frame dragging

Vassiliki Kalogera, Dimitrios Psaltis

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Recent x-ray variability observations of accreting neutron stars may provide the first evidence for frame dragging effects around spinning relativistic objects. Motivated by this possibility and its implications for neutron-star structural properties, we calculate new optimal bounds on the masses, radii, and moments of inertia of slowly rotating neutron stars that show kilohertz quasi-periodic oscillations (QPOs). These bounds are derived under minimal assumptions about the properties of matter at high densities and therefore are largely independent of the unknown equation of state. We further derive a semi-analytical upper bound on the neutron-star moment of inertia without making any assumptions about the equation of state of matter at any density. We use this upper bound to show that the maximum possible nodal precession frequency of an inclined circular orbit around a slowly spinning neutron star is νNP≃45.2(νs/300 Hz) Hz, where νs is the spin frequency of the neutron star. We conclude that the nodal-precession interpretation of low-frequency QPOs in accreting neutron stars is inconsistent with the beat-frequency interpretation of the kHz QPOs or the identification of the highest-frequency QPO with that of a circular Keplerian orbit in the accretion disk.

Original languageEnglish (US)
Article number024009
Pages (from-to)1-8
Number of pages8
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume61
Issue number2
StatePublished - Jan 15 2000
Externally publishedYes

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Moment of inertia
Neutron Stars
moments of inertia
neutron stars
Oscillation
oscillations
circular orbits
precession
Equation of State
metal spinning
equations of state
Orbit
Accretion Disks
Upper bound
beat frequencies
Optimal Bound
Beat
Inclined
Evidence
accretion disks

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Nuclear and High Energy Physics
  • Mathematical Physics
  • Physics and Astronomy (miscellaneous)

Cite this

Bounds on neutron-star moments of inertia and the evidence for general relativistic frame dragging. / Kalogera, Vassiliki; Psaltis, Dimitrios.

In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 61, No. 2, 024009, 15.01.2000, p. 1-8.

Research output: Contribution to journalArticle

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