Pairing properties and specific heat of the inner crust of a neutron star

Pastore, Alessandro

doi:10.1103/physrevc.91.015809

Cited by 16 publications

(26 citation statements)

References 55 publications

(114 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was shown that the transition temperature of the superfluid gas is correctly recovered, but the peak is still sharper than in the full HFB calculation. Moreover, in the full calculation a second peak at higher temperature can appear in the outer part of the inner crust, depending on the energy functional [5,9]. This peak corresponds to the temperature at which the whole system becomes non-superfluid, due to the pairing effect in the surface of the cluster.…”

Section: Computation Of the Total Energymentioning

confidence: 96%

See 1 more Smart Citation

Heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model

et al. 2015

View full text Add to dashboard Cite

International audienceBackground: Superfluidity in the crust is a key ingredient for the cooling properties of proto-neutron stars. Present theoretical calculations employ the quasiparticle mean-field Hartree-Fock-Bogoliubov theory with temperature-dependent occupation numbers for the quasiparticle states.Purpose: Finite temperature stellar matter is characterized by a whole distribution of different nuclear species. We want to assess the importance of this distribution on the calculation of heat capacity in the inner crust.Method: Following a recent work, the Wigner-Seitz cell is mapped into a model with cluster degrees of freedom. The finite temperature distribution is then given by a statistical collection of Wigner-Seitz cells. We additionally introduce pairing correlations in the local density BCS approximation both in the homogeneous unbound neutron component, and in the interface region between clusters and neutrons.Results: The heat capacity is calculated in the different baryonic density conditions corresponding to the inner crust, and in a temperature range varying from 100 KeV to 2 MeV. We show that accounting for the cluster distribution has a small effect at intermediate densities, but it considerably affects the heat capacity both close to the outer crust and close to the core. We additionally show that it is very important to consider the temperature evolution of the proton fraction for a quantitatively reliable estimation of the heat capacity.Conclusions: We present the first modelization of stellar matter containing at the same time a statistical distribution of clusters at finite temperature, and pairing correlations in the unbound neutron component. The effect of the nuclear distribution on the superfluid properties can be easily added in future calculations of the neutron star cooling curves. A strong influence of resonance population on the heat capacity at high temperature is observed, which deserves to be further studied within more microscopic calculations

show abstract

Section: Computation Of the Total Energymentioning

confidence: 96%

“…This decomposition of the Wigner-Seitz cell between cluster and gas, accounting for the excluded volume effect, was tried in the recent HFB analysis of Ref. [9]. It was shown that the transition temperature of the superfluid gas is correctly recovered, but the peak is still sharper than in the full HFB calculation.…”

Section: Computation Of the Total Energymentioning

confidence: 99%

Heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model

et al. 2015

View full text Add to dashboard Cite

show abstract

“…A semiclassical method that includes shell effects -namely the extended Thomas-Fermi plus Strutinsky integral method -was applied to assess the role of proton pairing [335]. It was found that pairing acts to smooth out the proton shell effects, without significantly changing the energetically favored value of Z, which was found to be close to 40. At the microscopic level, the Hartree-Fock-Bogolyubov theory [336] has been applied extensively in the past decade to determine the composition and pairing of crustal matter in neutron stars, as well as its specific heat, using the WS approximation; see [261,[337][338][339][340][341][342] and references therein for the earlier work. The key features related to the behavior of the relative magnitude of the gaps in the continuum and the cluster bound state discussed above are reproduced in this case as well.…”

Section: Pairing Patterns In Neutron Starsmentioning

confidence: 99%

Superfluidity in nuclear systems and neutron stars

2019

View full text Add to dashboard Cite

Nuclear matter and finite nuclei exhibit the property of superfluidity by forming Cooper pairs. We review the microscopic theories and methods that are being employed to understand the basic properties of superfluid nuclear systems, with emphasis on the spatially extended matter encountered in neutron stars, supernova envelopes, and nuclear collisions. Our survey of quantum many-body methods includes techniques that employ Green functions, correlated basis functions, and Monte Carlo sampling of quantum states. With respect to empirical realizations of nucleonic and hadronic superfluids, this review is focused on progress that has been made toward quantitative understanding of their properties at the level of microscopic theories of pairing, with emphasis on the condensates that exist under conditions prevailing in neutron-star interiors. These include singlet S-wave pairing of neutrons in the inner crust, and, in the quantum fluid interior, singlet-S proton pairing and triplet coupled P -F -wave neutron pairing. Additionally, calculations of weak-interaction rates in neutron-star superfluids within the Green function formalism are examined in detail. We close with a discussion of quantum vortex states in nuclear systems and their dynamics in neutron-star superfluid interiors. PACS. 97.60.Jd Neutron stars -21.65.+f Nuclear matter -47.37.+q Hydrodynamic aspects of superfluidity; quantum fluids -67.85.+d Ultracold gases, trapped gases -74.25.Dw Superconductivity phase diagrams Contents arXiv:1802.00017v4 [nucl-th] 26 Sep 2019 emerge in the interaction part of the Hamiltonian when evaluating Eq. (5) in terms of Bogolyubov operators vanish. Such terms would account for fluctuations in the system, but are beyond the scope of the present mean-field treatment. 4 Note that the variation δ(E − µN )/δn p,↑ , with up and vp held constant, yields the quantity Ep, confirming its interpretation. Armen Sedrakian, John W. Clark: Superfluidity in nuclear systems and neutron stars 5

show abstract

“…The set of these minima describes a path in the (Z, ρ b , R W S ) configuration space, hence defining in details the evolution of the structure of the inner crust of neutron stars from its outmost to its inmost regions. In the current article, we limit ourselves to the zero-temperature case, but the formalism can be extended to include the non-zero temperature case [41,42]. We investigate a region of the baryonic density that spans 0.0004 fm −3 ≤ ρ b ≤ 0.02 fm −3 .…”

Section: The Methodsmentioning

confidence: 99%

“…In the limit of vanishing pairing gap ∆ q nn ′ lj → 0 one retrieves the usual Hartree-Fock equations on a basis. More details on the solutions of these equations can be found in Refs [55,[60][61][62].…”

Section: A Nuclear Energy Enucmentioning

confidence: 99%

A new statistical method for the structure of the inner crust of neutron stars

Pastore¹,

Shelley²,

Baroni³

et al. 2017

J. Phys. G: Nucl. Part. Phys.

View full text Add to dashboard Cite

We investigated the structure of the low density regions of the inner crust of neutron stars using the Hartree-Fock-Bogoliubov (HFB) model to predict the proton content Z of the nuclear clusters and, together with the lattice spacing, the proton content of the crust as a function of the total baryonic density ρ b . The exploration of the energy surface in the (Z, ρ b ) configuration space and the search for the local minima require thousands of calculations. Each of them implies an HFB calculation in a box with a large number of particles, thus making the whole process very demanding. In this work, we apply a statistical model based on a Gaussian Process Emulator that makes the exploration of the energy surface ten times faster. We also present a novel treatment of the HFB equations that leads to an uncertainty on the total energy of ≈ 4 keV per particle. Such a high precision is necessary to distinguish neighbour configurations around the energy minima.

show abstract

Pairing properties and specific heat of the inner crust of a neutron star

Cited by 16 publications

References 55 publications

Heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model

Heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model

Superfluidity in nuclear systems and neutron stars

A new statistical method for the structure of the inner crust of neutron stars

Contact Info

Product

Resources

About