Viscosity of neutron star matter and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>r</mml:mi></mml:math>-modes in rotating pulsars

Kolomeitsev, E. É.; Voskresensky, D. N.

doi:10.1103/physrevc.91.025805

Cited by 55 publications

(54 citation statements)

References 119 publications

(396 reference statements)

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“…III A 4). The phonon coupling with the Bogoliubov quasiparticles was investigated by Kolomeitsev and Voskresensky [185] with a similar conclusion. Other low-energy excitations which can exist in neutron star cores in the presence of nucleon Cooper pairing are as follows.…”

Section: Effects Of Cooper Pairingsupporting

confidence: 54%

Reaction Rates and Transport in Neutron Stars

Schmitt

Shternin

2018

Astrophysics and Space Science Library

100

122

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Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions. arXiv:1711.06520v3 [astro-ph.HE] 29 Oct 2018 65 References 66 I. INTRODUCTION A. ContextTransport describes how conserved quantities such as energy, momentum, particle number, or electric charge are transferred from one region to another. Such a transfer occurs if the system is out of equilibrium, for instance through a temperature gradient or a non-uniform chemical composition. Different theoretical methods are used to understand transport, depending on how far the system is away from its equilibrium state. If the system is close to equilibrium locally and perturbations are on large scales in space and time, hydrodynamics is a powerful technique. Further away from equilibrium other techniques are required, for example kinetic theory, which can also be used to provide the transport coefficients needed in the hydrodynamic equations. In any case, transport is determined by interactions on a microscopic level, and it is the resulting transport properties that we are concerned with in this review.Signals from neutron stars are sensitive to equilibrium properties such as the equation of state but also, to a large extent, to transport properties -here, by neutron stars we mean all objects with a radius of about 10 km and a mass of about 1-2 solar masses, including the possibilities of hybrid stars, which have a quark matter core, and pure quark stars. Therefore, understanding transport is crucial to interpret astrophysical observations, and, turning the argument around, we can use astrophysical observations to improve our understanding of transport in dense matter and thus ultimately our understanding of the microscopic interactions.Transport properties are most commonly computed from particle collisions. (Although, in strongly coupled systems, the picture of well-defined particles scattering off each other has to be taken with care.) These can be scattering processes in which energy and momentum is exchanged without changing the chemical composition of the system, or these can be flavor-changing processes from the electroweak interaction. Understanding transport thus amounts to understanding the rates of these processes, as a function of temperature and density. Electroweak processes are well understood, but large uncertainties arise if the strong interaction is involved in a reaction that contributes to transport. Therefore, approximations such as weak-coupling techniques or one-pion exchange for nucleon-nucleon collisions are being used, and efforts in current research aim at improving these approximations.In a neutron star, most of the particles involved in these processes are fermions: electrons, muons, neutrinos, neutrons, protons, hyperons, and quarks. Since the Fermi momenta of these fermions are typically much larger tha...

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Section: Effects Of Cooper Pairingsupporting

confidence: 54%

Reaction Rates and Transport in Neutron Stars

Schmitt

Shternin

2018

Astrophysics and Space Science Library

100

122

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“…The results of the calculations were confronted to the data on the T s −t plane [35,19,30,45,46,49] demonstrating an overall agreement, without necessity to assume presence of the DU processes. Moreover, the absence of sub-millisecond pulsars might be naturally explained within the nuclear medium cooling scenario [66,67]. Two possibilities, one which allows for the PU processes and other one not allowing the pion condensation, were considered.…”

Section: Introductionmentioning

confidence: 99%

Cooling of neutron stars in “nuclear medium cooling scenario” with stiff equation of state including hyperons

2018

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We demonstrate that the existing neutron-star cooling data can be appropriately described within "the nuclear medium cooling scenario" including hyperons under the assumption that different sources have different masses. We use a stiff equation of state of the relativistic mean-field model MKVORHφ with hadron effective couplings and masses dependent on the scalar field. It fulfills a large number of experimental constraints on the equation of state of the nuclear matter including the 2 M lower bound for the maximum predicted neutron-star mass and the constraint for the pressure from the heavy-ion particle flow. We select appropriate 1 S 0 proton and Λ hyperon pairing gap profiles from those exploited in the literature and allow for a variation of the effective pion gap controlling the efficiency of the medium modified Urca process. The 3 P 2 neutron pairing gap is assumed to be negligibly small in our scenario. The possibility of the pion, kaon and charged ρ-meson condensations is for simplicity suppressed. The resulting cooling curves prove to be sensitive to the value and the density dependence of the pp pairing gap and rather insensitive to the values of the 1 S 0 neutron pairing gaps. Inputs for the cooling model 13 4 Cooling history of neutron stars. Numerical results. 17

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“…Up-to-date models of r-mode instability embrace full diversity of neutron star microphysics: they depend on NS core composition (e.g., Jones 2001;Lindblom & Owen 2002;Nayyar & Owen 2006;Andersson, Haskell & Comer 2010;Alford & Schwenzer 2014a), superfluidity (Lindblom & Mendell 2000;Andersson & Comer 2001;Yoshida & Lee 2003b,a;Lee & Yoshida 2003;Andersson, Glampedakis & Haskell 2009;Haskell, Andersson & Passamonti 2009;Gusakov, Chugunov & Kantor 2014a,b;Dommes, Kantor & Gusakov 2018), crust-core coupling (Rieutord 2001;Levin & Ushomirsky 2001b;Glampedakis & Andersson 2006a,b), in-medium effects (Kolomeitsev & Voskresensky 2015), etc. To derive this microphysical information from observations properly, one should have an accurate theory, describing evolution of CFS unstable star observational features.…”

Section: Introductionmentioning

confidence: 99%

Long-term evolution of CFS-unstable neutron stars and the role of differential rotation on short time-scales

Chugunov

2018

Monthly Notices of the Royal Astronomical Society

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I consider differential rotation, associated with radiation-driven Chandrasekhar-Friedman-Schutz (CFS) instability and its possible observational evidences. I focus on the evolution of the apparent spin frequency, which is typically associated with the motion of a specific point on the stellar surface (e.g., polar cap). I start from long-term evolution (on the timescale when instability significantly changes the spin frequency). For this case, I reduce evolution equations to one differential equation and demonstrate that it can be directly derived from energy conservation law. This equation governs evolution rate through sequence of thermally equilibrium states and provides linear coupling for the cooling power and rotation energy losses via gravitational wave emission. In particular, it shows that differential rotation do not affect long-term spin-down. On the contrary, on the short timescales, differential rotation can significantly modify the apparent spin-down, if one examines a strongly unstable star with very small initial amplitude of unstable mode. This statement is confirmed by consideration of Newtonian non-magnetized perfect fluid and dissipative stellar models as well as magnetized stellar model. For example, despite that widely applied evolution equations predict effective spin to be constant in absence of dissipation, the CFS-unstable star should be observed as spinning-down. However, effects of differential rotation on apparent spin-down are negligible for realistic models of neutron star recycling, unless: (1) the neutron star is not magnetized, and (2) r-mode amplitude is modulated faster than the shear viscosity dissipation timescale, being large enough that spin-down can be measured on modulation timescale.

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Viscosity of neutron star matter andr-modes in rotating pulsars

Cited by 55 publications

References 119 publications

Reaction Rates and Transport in Neutron Stars

Reaction Rates and Transport in Neutron Stars

Cooling of neutron stars in “nuclear medium cooling scenario” with stiff equation of state including hyperons

Long-term evolution of CFS-unstable neutron stars and the role of differential rotation on short time-scales

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