Beta equilibrium under neutron star merger conditions

Alford, Mark G.; Haber, Alexander; Harris, Steven P.; Zhang, Ziyuan

doi:10.48550/arxiv.2108.03324

Cited by 5 publications

(7 citation statements)

References 52 publications

(76 reference statements)

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“…It can be seen in addition that, as noticed previously by Alford & Harris (2018); Alford et al (2021), β-equilibrium in neutrino transparent matter at non zero temperature does not occur at the point where chemical potentials fulfil the usual β-equilibrium condition for cold neutron stars (µn = µp + µe which stems from the Fermi surface approximation, indicated by the red dashed line in Fig. 1) but depends explicitly on the neutrino production rates instead.…”

Section: Direct Urca Processessupporting

confidence: 56%

“…In the same way, during the late stages of PNS evolution they can become strongly suppressed for some neutrino energies. In this case, the so-called modified Urca (mUrca) processes become relevant, see also the discussion of β-equilibrium in the hot merger remnant in Alford & Harris (2018) and Alford et al (2021). They involve a spectator nucleon N allowing to lift the kinematic restrictions of the direct processes :…”

Section: Modified Urca Processesmentioning

confidence: 99%

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Proto-neutron star evolution with improved charged-current neutrino-nucleon interactions

Pascal,

Novak,

Oertel

2022

Preprint

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We perform simulations of the Kelvin-Helmholtz cooling phase of proto-neutron stars with a new numerical code in spherical symmetry and using the quasi-static approximation. We use for the first time the full set of charged-current neutrino-nucleon reactions, including neutron decay and modified Urca processes, together with the energy-dependent numerical representation for the inclusion of nuclear correlations with random-phase approximation. Moreover, convective motions are taken into account within the mixing-length theory. As we vary the assumptions for computing neutrino-nucleon reaction rates, we show that the dominant effect on the cooling timescale, neutrino signal and composition of the neutrino-driven wind comes from the inclusion of convective motion. Computation of nuclear correlations within the random phase approximation, as compared to mean field approach, has a relatively small impact.

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Section: Direct Urca Processessupporting

confidence: 56%

Section: Modified Urca Processesmentioning

confidence: 99%

Proto-neutron star evolution with improved charged-current neutrino-nucleon interactions

Pascal,

Novak,

Oertel

2022

Preprint

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“…Combining the weak-equilibrium and charge neutrality conditions we are now in a position to compute the EoS of stellar matter both in the trapped and un-trapped neutrino regimes. 1 1 Note that it is implicitly assumed that the matter is under detailed balance with respect to Urca processes; if such condition is violated then additional "isospin chemical potential" arises [58,59]. Also, note that we do not constrain particles to their Fermi surfaces and any corrections associated with the finite temperature features of the Fermi distribution function are included in our β-equilibratium condition.…”

Section: Thermodynamic Conditions In Supernovas and Merger Remnantsmentioning

confidence: 99%

Equation of state and composition of proto-neutron stars and merger remnants with hyperons

Sedrakian,

Harutyunyan

2021

Preprint

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Finite-temperature equation of state (EoS) and composition of dense nuclear and hypernuclear matter under conditions characteristic for neutron star binary merger remnants and supernovas are discussed. We consider both the neutrino free-streaming and the trapped regimes which are separated by a temperature of a few MeV. The formalism is based on covariant density functional (CDF) theory for the full baryon octet with density-dependent couplings, suitably adjusted in the hypernuclear sector. The softening of the EoS with the introduction of the hyperons is quantified under various conditions of lepton fractions and temperatures. We find that Λ, Ξ − , and Ξ 0 hyperons appear in the given order with the sharp density increase at zero temperature at the threshold being replaced by an extended increment over a wide density range at high temperatures. The Λ hyperon survives in the deep subnuclear regime. The triplet of Σs is suppressed in cold hypernuclear matter up to around seven times the nuclear saturation density, but appears in significant fractions at higher temperatures T ≥ 20 MeV in both supernova and merger remnant matter. We point out that there exists a special isospin degeneracy point where the baryon abundances within each of the three isospin-multiplets are equal to each other as a result of (approximate) isospin symmetry. At that point the charge chemical potential of the system vanishes. We find that under the merger remnant conditions the fractions of electron and µ-on neutrinos are close and are about 1%, whereas in the supernova case, we find only a significant fraction (∼10%) of electron neutrinos, given that in this case, the µ-on lepton number is zero.

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“…In any case, a transient hot object is formed and, therefore, the spectrum of gravitational waves emitted in this phase (which can be observed with advanced gravitational wave instruments) will carry imprints of the EoS of hot and dense matter. This EoS also determines the stability of the remnant object and thus the outcome of the transient evolution [20] as well as the efficacy of dissipative processes [21][22][23][24][25][26][27][28] that should be included [27] in the frequently employed ideal hydrodynamics simulations.…”

Section: Introductionmentioning

confidence: 99%

Delta-resonances and hyperons in proto-neutron stars and merger remnants

Sedrakian¹,

Harutyunyan²

2022

Preprint

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The equation of state (EoS) and composition of dense and hot ∆-resonance admixed hypernuclear matter is studied under conditions that are characteristic of neutron star binary merger remnants and supernovas. The cold, neutrino free regime is also considered as a reference for the astrophysical constraints on the EoS of dense matter. Our formalism uses the covariant density functional (CDF) theory successfully adapted to include the full J P = 1/2 + baryon octet and non-strange members of J P = 3/2 + decouplet with density-dependent couplings that have been suitably adjusted to the existing laboratory and astrophysical data in the nuclear and hypernuclear sectors. The effect of ∆-resonances at finite temperatures is to soften the EoS of hypernuclear matter at intermediate densities and stiffen it at high densities. At low temperatures, the heavy baryons Λ, ∆ − ,Ξ − , Ξ 0 and ∆ 0 appear in the given order if the ∆-meson couplings are close to those for the nucleon-meson couplings. As is the case for hyperons, the thresholds of ∆-resonances move to lower densities with the increase of temperature indicating a significant fraction of ∆s in the low-density subnuclear regime. We find that the ∆-resonances comprise a significant fraction of baryonic matter, of the order of 10% at temperatures of the order of several tens of MeV in the neutrino-trapped regime and, thus, may affect the supernova and binary neutron star dynamics.PACS. 9 7.60.Jd (Neutron stars) -2 6.60.+c (Nuclear matter aspects of neutron stars) -2 1.65.+f (Nuclear matter)

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Beta equilibrium under neutron star merger conditions

Cited by 5 publications

References 52 publications

Proto-neutron star evolution with improved charged-current neutrino-nucleon interactions

Proto-neutron star evolution with improved charged-current neutrino-nucleon interactions

Equation of state and composition of proto-neutron stars and merger remnants with hyperons

Delta-resonances and hyperons in proto-neutron stars and merger remnants

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