Bulk viscosity in a hyperonic star and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>r</mml:mi></mml:mrow></mml:math>-mode instability

Jha, Tarun; Mishra, Hari Niwas; Sreekanth, V.

doi:10.1103/physrevc.82.025803

Cited by 19 publications

(16 citation statements)

References 76 publications

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“…This fact opens the possibility of investigating the internal composition of compact stars by studying the viscosity of the different possible high density phases which can appear in these stellar objects. A number of papers are currently present in the literature about the shear and bulk viscosities of nucleonic matter [3][4][5][6][7], hyperonic matter [8][9][10][11][12][13][14], kaon condensed matter [15,16], pure quark phases [17][18][19][20][21][22][23][24][25][26][27], and mixed phases [28]. Interestingly, by studying the so called "window of instability" of the r-modes, which is determined by the shear and the bulk viscosity of the matter, it was pointed out in [29] that a detection of a sub-millisecond rotating star would indicate the existence of a very viscous phase in the star with only quark or hybrid stars as possible candidates.…”

Section: Introductionmentioning

confidence: 99%

Magnetic fields generated by r-modes in accreting quark stars

Bonanno

Cuofano

Drago

et al. 2010

A&A

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We show that the r-mode instability can generate strong toroidal fields in the core of accreting millisecond quark stars by inducing differential rotation. We follow the spin frequency evolution on a long time-scale, taking into account the magnetic damping rate in the evolution equations of r-modes. The maximum spin frequency of the star is only marginally lower than without the magnetic field. The late-time evolution of the stars that enter the r-mode instability region is instead quite different if the generated magnetic fields are taken into account: they leave the millisecond pulsar region and become radio pulsars.

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Section: Introductionmentioning

confidence: 99%

Magnetic fields generated by r-modes in accreting quark stars

Bonanno

Cuofano

Drago

et al. 2010

A&A

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“…Unfortunately, there is great uncertainty about the amount of viscosity inside neutron stars since it depends sensitively on the composition of matter which is uncertain beyond few times the nuclear saturation density [51][52][53][54][55]. If the damping time due to viscous forces is long enough, radial pulsations in magnetars can leave an imprint in the microstucture of magnetar flare lightcurves opening a new window for the study of highly magnetized ultradense matter.…”

Section: Results and Conclusionmentioning

confidence: 99%

Properties of strongly magnetized ultradense matter and its effects on magnetar pulsations

2016

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We investigate the effect of strong magnetic fields on the adiabatic radial oscillations of hadronic stars. We describe magnetized hadronic matter within the framework of the relativistic nonlinear Walecka model and integrate the equations of relativistic radial oscillations to determine the fundamental pulsation mode. We consider that the magnetic field increases, in a density dependent way, from the surface, where it has a typical magnetar value of 10 15 G, to the interior of the star where it can be as large as 3 × 10 18 G. We show that magnetic fields of the order of 10 18 G at the stellar core produce a significant change in the frequency of neutron star pulsations with respect to unmagnetized objects. If radial pulsations are excited in magnetar flares, they can leave an imprint in the flare lightcurves and open a new window for the study of highly magnetized ultradense matter.

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“…or direct and modified hyperonic Urca (see Equations ( 18) and ( 19)) contribute to the bulk viscosity and dominate it for densities above 2-3 times the nuclear saturation density. Hyperon bulk viscosity has been considered by several authors, see, e.g., [215][216][217][218][219][220][221][222][223][224][225][226][227][228][229].…”

Section: Hyperons and R-modesmentioning

confidence: 99%

Hyperons in Finite and Infinite Nuclear Systems

Vidaña

2021

Universe

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In this work, we shortly review the role and properties of hyperons in finite and infinite nuclear systems such as hypernuclei and neutron stars. Particularly, we describe different production mechanisms of hypernuclei, discuss some aspects of their γ-ray spectroscopy and their weak decay modes, and give a few strokes on their theoretical description. We reexamine also the role played by hyperons on the properties of neutron and proto-neutron stars with a special emphasis on the well-known “hyperon puzzle”, of which we discuss some of the solutions that have been proposed to tackle this problem. Finally, we review the role of hyperons on the cooling properties of newly born neutron stars and on the so-called r-mode instability.

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Bulk viscosity in a hyperonic star andr-mode instability

Cited by 19 publications

References 76 publications

Magnetic fields generated by r-modes in accreting quark stars

Magnetic fields generated by r-modes in accreting quark stars

Properties of strongly magnetized ultradense matter and its effects on magnetar pulsations

Hyperons in Finite and Infinite Nuclear Systems

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