Innermost stable circular orbits around magnetized rotating massive stars

Gómez, J. D. Sanabria; Hernández‐Pastora, J. L.; Dubeibe, F. L.

doi:10.1103/physrevd.82.124014

Cited by 11 publications

(24 citation statements)

References 27 publications

(45 reference statements)

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“…This effect could be explained in terms of the contributions of the multipolar moments of the solution (see e.g. [16] and [17]). On the other hand, when considering the dependence of the radius of the ISCO with the angular momentum J, electric charge Q and separation between the sources R, a similar (almost linear) dependence with the three parameters is observed.…”

Section: Discussionmentioning

confidence: 99%

Geodesic motion in a stationary dihole spacetime

Dubeibe¹,

Sanabria-Gómez

2016

Phys. Rev. D

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The knowledge of the properties of the different exact solutions modeling binary systems, is a necessary step towards the classification of physically suitable solutions and its corresponding limits of applicability. In the present paper, we perform an analysis of the geodesics around two counter-rotating Kerr-Newman black holes endowed with opposite electric charges, which achieve equilibrium by means of a strut between their constituents. We find that bounded and unbounded orbits are possible. However, test particles may cross between the black holes only if their angular momentum equals zero, otherwise, there exist a repulsive potential, which prohibits such orbits. Two important aspects are pointed out for these trajectories: (i) the motion of photons is affected once crossing the strut; and (ii) massive particles exhibit oscillatory motion, as a first analog of the Sitnikov problem in general relativity. The radius of the innermost stable circular orbit as a function of the physical parameters of the black holes is also investigated.

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Section: Discussionmentioning

confidence: 99%

Geodesic motion in a stationary dihole spacetime

Dubeibe¹,

Sanabria-Gómez

2016

Phys. Rev. D

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“…The generalization of the present work to the electrovacuum case is important to establish the influence of the magnetic dipole and quadrupole moments on the orbital motion of particles around compact objects (see, e.g., Bakala et al 2010Bakala et al , 2012Sanabria-Gómez et al 2010). …”

Section: Discussionmentioning

confidence: 99%

“…Although for the case of compact stars contributions from the magnetic field could be relevant (see, e.g., Bakala et al 2010Bakala et al , 2012Sanabria-Gómez et al 2010), we focus in this work on the frequencies of neutral particles orbiting a neutral compact object. We calculate here the Keplerian ν K = Ω K /(2π ), framedragging (Lense-Thirring) ν LT = Ω LT /(2π ), radial oscillation and precession ν where, for circular orbits, the energy E and angular momentum L are determined by the conditions V = 0 and dV /dρ = 0 (see Equations (22) and (23)).…”

Section: Orbital Motion Frequencies On the Equatorial Planementioning

confidence: 99%

“…The lack of influence of the electromagnetic field on the curvature could be overcome, at least for the Kerr case, by considering the simplest generalization of the Kerr-Newman derived by Manko (1993; for a typo-free version see Pachón & Dubeibe 2011). The effects of the magnetic dipole on the location of the ISCO, within the PRS solution, have been investigated by Sanabria-Gómez et al (2010).…”

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confidence: 99%

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On the Relativistic Precession and Oscillation Frequencies of Test Particles Around Rapidly Rotating Compact Stars

Pachón¹,

Rueda²,

Valenzuela-Toledo³

2012

ApJ

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Whether or not analytic exact vacuum (electrovacuum) solutions of the Einstein (Einstein-Maxwell) field equations can accurately describe the exterior space-time of compact stars still remains an interesting open question in relativistic astrophysics. As an attempt to establish their level of accuracy, the radii of the innermost stable circular orbits (ISCOs) of test particles given by analytic exterior space-time geometries have been compared with those given by numerical solutions for neutron stars (NSs) obeying a realistic equation of state (EOS). It has been so shown that the six-parametric solution of Pachón et al. (PRS) more accurately describes the NS ISCO radii than other analytic models do. We propose here an additional test of accuracy for analytic exterior geometries based on the comparison of orbital frequencies of neutral test particles. We compute the Keplerian, frame-dragging, and precession and oscillation frequencies of the radial and vertical motions of neutral test particles for the Kerr and PRS geometries and then compare them with the numerical values obtained by Morsink & Stella for realistic NSs. We identify the role of high-order multipole moments such as the mass quadrupole and current octupole in the determination of the orbital frequencies, especially in the rapid rotation regime. The results of this work are relevant to cast a separatrix between black hole and NS signatures and to probe the nuclear-matter EOS and NS parameters from the quasi-periodic oscillations observed in low-mass X-ray binaries.

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“…In particular, one expects contributions to the radius of the innermost stable circular orbit (ISCO) (Sanabria-Gómez et al 2010), the Keplerian frequency, frame-dragging frequency, precession and oscillation frequencies of the radial and vertical motions of test particles , Bakala et al 2010, and perhaps to other physical properties such as the angular momentum of the emitted radiation (Tamburini et al 2011), which could reveal some properties of accretion disks and therefore of the compact object (Bocquet et al 1995, Konno et al 1999, Broderick et al 2000, Cardall et al 2001. In other words, to construct a more realistic theoretical description that includes purely relativistic effects such as the modification of the gravitational interaction by electromagnetic fields, it is necessary to use a complete solution of the full Einstein-Maxwell field equations that takes into account all the possible characteristics of the compact object.…”

Section: Introductionmentioning

confidence: 99%

Innermost stable circular orbits and epicyclic frequencies around a magnetized neutron star

2013

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A full-relativistic approach is used to compute the radius of the innermost stable circular orbit (ISCO), the Keplerian, frame-dragging, precession and oscillation frequencies of the radial and vertical motions of neutral test particles orbiting the equatorial plane of a magnetized neutron star. The space-time around the star is modelled by the six parametric solution derived by Pachón et al. (2012) It is shown that the inclusion of an intense magnetic field, such as the one of a neutron star, have non-negligible effects on the above physical quantities, and therefore, its inclusion is necessary in order to obtain a more accurate and realistic description of physical processes, such as the dynamics of accretion disks, occurring in the neighbourhood of this kind of objects. The results discussed here also suggest that the consideration of strong magnetic fields may introduce non-negligible corrections in, e.g., the relativistic precession model and therefore on the predictions made on the mass of neutron stars.

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Innermost stable circular orbits around magnetized rotating massive stars

Cited by 11 publications

References 27 publications

Geodesic motion in a stationary dihole spacetime

Geodesic motion in a stationary dihole spacetime

On the Relativistic Precession and Oscillation Frequencies of Test Particles Around Rapidly Rotating Compact Stars

Innermost stable circular orbits and epicyclic frequencies around a magnetized neutron star

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