Highly accurate calculation of rotating neutron stars

Ansorg, Marcus; Kleinwächter, Andreas; Meinel, Reinhard

doi:10.1051/0004-6361:20011643

Cited by 51 publications

(80 citation statements)

References 35 publications

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“…On these grounds highly accurate numerical schemes like [54][55][56] were developed. Among other things, it is useful to abandon the Schwarzschild coordinates in favor of e.g., quasiisotropic coordinates.…”

Section: Rotating Stars In General Relativitymentioning

confidence: 99%

“…When properly implemented, the difference between the series expansion and the real solution vanishes like e −N , where N is the number of expansion coefficients (the evanescent error). As an example of a real implementation, the formulation of [54] is using spectral methods in a numerical library LORENE 4 in a nrotstar code; other highly accurate implementations can easily reach machine precision [56]. Note also that numerical relativity with spectral methods is particularly suitable for precision studies of instabilities, due to very low numerical viscosity of spectral methods (see e.g., [65][66][67][68] and sect.…”

Section: Accuracy Of Solutionsmentioning

confidence: 99%

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Rotating neutron stars with exotic cores: masses, radii, stability

Haensel¹,

Bejger²,

Fortin³

et al. 2016

Eur. Phys. J. A

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Abstract.A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency (716 Hz) and the maximum measured mass (2M ). The present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a first-order phase transition, both between pure phases, and into a mixed-phase state, are reviewed. The case of two disjoint families (branches) of rotating neutron stars is discussed and generic features of neutron-star families and of core-quakes triggered by the instabilities are considered.

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Section: Rotating Stars In General Relativitymentioning

confidence: 99%

Section: Accuracy Of Solutionsmentioning

confidence: 99%

Rotating neutron stars with exotic cores: masses, radii, stability

Haensel¹,

Bejger²,

Fortin³

et al. 2016

Eur. Phys. J. A

View full text Add to dashboard Cite

show abstract

“…In strong contrast, the energy associated with J T corresponds to an increasing function which reaches its maximum value at the surface of the star. We have shown these opposed behaviors for the Schwarzschild (constant-density) star, as well as for rigidly rotating stationary stars which can contain an ergoregion [2]. The unphysical behavior of J T is not a surprise.…”

Section: Discussionmentioning

confidence: 71%

“…We will choose here the KV which is aligned with the fluid worldlines, so that in comoving coordinates, it can be expressed as ξ a = e U u a = δ a (t) . Therefore, according to (2) and (16), the conserved currents are…”

Section: A Rigidly Rotating Starsmentioning

confidence: 99%

Almost-Killing conserved currents: A general mass function

2014

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A new class of conserved currents, describing non-gravitational energy-momentum density, is presented. The proposed currents do not require the existence of a (timelike) Killing vector, and are not restricted to spherically symmetric spacetimes (or similar ones, in which the Kodama vector can be defined). They are based instead on almost-Killing vectors, which could in principle be defined on generic spacetimes. We provide local arguments, based on energy density profiles in highly simplified (stationary, rigidly-rotating) star models, which confirm the physical interest of these

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“…All five limiting curves were found to circumscribe entirely the general relativistic solution for homogeneous star models that are continuously joined to the static Schwarzschild solution -hereafter called the "generalized Schwarzschild solution" 2 . This was done using the recently developed AKM method (Ansorg et al 2002(Ansorg et al , 2003c, which allows one to solve the Einstein equations to high accuracy even for critical configurations. In particular we are able to determine to high precision the extreme configuration possessing both a mass shed and infinite central pressure.…”

Section: Introductionmentioning

confidence: 99%

Maximal mass of uniformly rotating homogeneous stars in Einsteinian gravity

Schöbel

Ansorg

2003

A&A

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Abstract. Using a multi domain spectral method, we investigate systematically the general-relativistic model for axisymmetric uniformly rotating, homogeneous fluid bodies generalizing the analytically known Maclaurin and Schwarzschild solutions. Apart from the curves associated with these solutions and a further curve of configurations that rotate at the mass shedding limit, two more curves are found to border the corresponding two parameter set of solutions. One of them is a Newtonian lens shaped sequence bifurcating from the Maclaurin spheroid sequence, while the other one corresponds to highly relativistic bodies with an infinite central pressure. The properties of the configuration for which both the gravitational and the baryonic masses, moreover angular velocity, angular momentum as well as polar red shift obtain their maximal values are discussed in detail. In particular, by comparison with the static Schwarzschild solution, we obtain an increase of 34.25% in the gravitational mass. Moreover, we provide exemplarily a discussion of angular velocity and gravitational mass on the entire solution class.

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Highly accurate calculation of rotating neutron stars

Cited by 51 publications

References 35 publications

Rotating neutron stars with exotic cores: masses, radii, stability

Rotating neutron stars with exotic cores: masses, radii, stability

Almost-Killing conserved currents: A general mass function

Maximal mass of uniformly rotating homogeneous stars in Einsteinian gravity

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