In this work we calculate the total mass, radius, moment of inertia, and surface gravitational re... more In this work we calculate the total mass, radius, moment of inertia, and surface gravitational redshift for neutron stars using various equations of state (EOS). Modern meson-exchange potential models are used to evaluate the G-matrix for asymmetric nuclear matter. We calculate both a nonrelativistic and a relativistic EOS. Of importance here is the fact that relativistic Brueckner-Hartree-Fock calculations for symmetric nuclear matter fit the empirical data, which are not reproduced by non-relativistic calculations. Relativistic effects are known to be important at high densities, giving an increased repulsion. This leads to a stiffer EOS compared to the EOS derived with a nonrelativistic approach. Both the non-relativistic and the relativistic EOS yield moments of inertia and redshifts in agreement with the accepted values. The relativistic EOS yields, however, too large mass and radius. The implications are discussed.
We present results for the 3 P 2-3 F 2 pairing gap in neutron matter with several realistic nucle... more We present results for the 3 P 2-3 F 2 pairing gap in neutron matter with several realistic nucleon-nucleon potentials, in particular with recent, phase-shift equivalent potentials. We find that their predictions for the gap cannot be trusted at densities above ρ ≈ 1.7ρ 0 , where ρ 0 is the saturation density for symmetric nuclear matter. In order to make predictions above that density, potential models which fit the nucleon-nucleon phase shifts up to about 1 GeV are required.
We study the symmetry energy in infinite nuclear matter employing a non-relativistic Brueckner-Ha... more We study the symmetry energy in infinite nuclear matter employing a non-relativistic Brueckner-Hartree-Fock approach and using various new nucleon-nucleon (NN) potentials, which fit np and pp scattering data very accurately. The potential models we employ are the recent versions of the Nijmegen group, Nijm-I, Nijm-II and Reid93, the Argonne V 18 potential and the CD-Bonn potential. All these potentials yield a symmetry energy which increases with density, resolving a discrepancy that existed for older NN potentials. The origin of remaining differences is discussed.
In this work we calculate neutron and proton energy gaps in neutron star matter, using the Bonn m... more In this work we calculate neutron and proton energy gaps in neutron star matter, using the Bonn meson{exchange interactions and a model{space approach to the gap equation. This approach allows a consistent calculation of energy gaps and single particle energies with the model{space Brueckner{ Hartree{Fock (MBHF) method, without double counting of two{particle correlations. Neutron energy gaps are calculated at zero and nite temperature. Proton energy gaps are calculated at beta equilibrium, and it is shown that the inclusion of muons has a signi cant e ect. The results are compared with those of other works, and the implications for neutron star physics are brie y discussed.
Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine lan... more Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine landslide and flow ahead of the front. Data gathered from different sliding areas highlight some properties of outrunner blocks and in particular their inordinate mobility reflected in runouts of up to 25 kilometres, even on very gentle slopes. Blocks may produce an erosion glide track on the sea floor few centimetres to several metres deep, which in some cases exhibits regularly spaced grooves along the flow direction. Understanding the dynamics of outrunner blocks may shed light on the flow and lubrication of submarine landslides. We develop a simple hydrodynamic model of a rigid block interacting with ambient water and subject to lubrication with the sea floor, and calculate numerically the equation of motion for the block. We find that as a consequence of lift forces and water lubrication, the block may reach long runouts, in agreement with data. When the block is moving at high speed, we find an oscillating solution to the equations of motion which could explain the creation of dashed grooves.
Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine lan... more Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine landslide and flow ahead of the front. Data gathered from different sliding areas highlight some properties of outrunner blocks and in particular their inordinate mobility reflected in runouts of up to 25 kilometres, even on very gentle slopes. Blocks may produce an erosion glide track on the sea floor few centimetres to several metres deep, which in some cases exhibits regularly spaced grooves along the flow direction. Understanding the dynamics of outrunner blocks may shed light on the flow and lubrication of submarine landslides. We develop a simple hydrodynamic model of a rigid block interacting with ambient water and subject to lubrication with the sea floor, and calculate numerically the equation of motion for the block. We find that as a consequence of lift forces and water lubrication, the block may reach long runouts, in agreement with data. When the block is moving at high speed, we find an oscillating solution to the equations of motion which could explain the creation of dashed grooves.
We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with... more We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with nucleonic and hyperonic degrees of freedom, employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. It is found that the only strange baryons emerging in βstable matter up to total baryonic densities of 1.2 fm -3 are Σ -and Λ. The corresponding equations of state are then used to compute properties of neutron stars such as masses and radii.
Deep-sea deposits from submarine landslides, debris flows, and turbidity currents have been recov... more Deep-sea deposits from submarine landslides, debris flows, and turbidity currents have been recovered hundreds of kilometres from inland, even along very gentle seabed slopes (Bugge et al. 1988). This high mobility may be partly explained considering the large sediment volumes associated with submarine mass-wasting. An example is the Storegga landslide on the Norwegian margin, which occurred about 9,000 years ago and ran on an average slope angle of only one degree. With its 3000 km of volume or more, this landslide dwarfs the largest subaerial landslides. Because large landslides usually reach longer horizontal runout than the small ones (the "volume effect"), it seems natural that subaqueous landslides should be more mobile. However, subaqueous landslides appear to be more mobile even when compared to subaerial landslides of the same volume. A better parameter quantifying the flow capacity of a landslide is the runout ratio, defined as the height of fall in the gravity f...
Several submarine debris flows show an apparently chaotic frontal part with blocks of variable si... more Several submarine debris flows show an apparently chaotic frontal part with blocks of variable size (from roughly tens to some hundreds of metres) located some distance beyond the front of the main deposits. This outrunner phenomenon was studied both in the field and in laboratory experiments. Depositional patterns in a field case (Finneidfjord, northern Norway) are classified from the outer distal part of the debris flow to the outermost outrunner block. Similar patterns were found in experimental debris flows, and we suggest that flow processes in the laboratory are applicable to the field example. Theoretical investigations are applied to assess frontal dynamics and especially the formation and motion of outrunner blocks. As the front of the debris flow pushes through ambient water, a combination of front pressure and lift force allows for intrusion of a water layer underneath the front (hydroplaning). This water layer reduces basal friction and induces tensile stresses farther b...
The aim of this work is to study the motion of a rigid streamlined object close to an inclined pl... more The aim of this work is to study the motion of a rigid streamlined object close to an inclined plane. A two-dimensional, small-scale model of a rigid block subjected to gravity is presented combined with the complete dynamical interaction with the surrounding liquid. Both the linear and rotational equations of motion of the body are coupled to the Navier-Stokes equations for the fluid flow using Comsol Multiphysics. A circulation of the fluid around the body is observed, and it generates a strong lift force that is sufficient to keep it completely separated from the bed, while it is travelling down slope. This water lubricating effect, also called hydroplaning has been recognized as an important effect to explain an extraordinary mobility of submarine slides. For the simple shapes studied in this work, we find that the motion becomes unsteady if the densimetric Froude exceeds 0.7.
We present results from many-body calculations for \beta-stable neutron star matter with nucleoni... more We present results from many-body calculations for \beta-stable neutron star matter with nucleonic and hyperonic degrees of freedom, employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. It is found that the only strange baryons emerging in \beta-stable matter up to total baryonic densities of 1.2 fm^{-3} are \Sigma^- and \Lambda. The corresponding equations of state are thence used to compute properties of neutron stars such as the masses, moments of inertia and radii. We also study the possibility of forming a hyperon superfluid and discuss its implications for neutron stars.
In this work we calculate the total mass, radius, moment of inertia, and surface gravitational re... more In this work we calculate the total mass, radius, moment of inertia, and surface gravitational redshift for neutron stars using various equations of state (EOS). The latter are derived from the recent meson-exchange potential models of the Bonn group, and we derive both a non-relativistic and a relativistic EOS. Of importance here is the fact that relativistic Brueckner-Hartree-Fock calculations for symmetric nuclear matter meet the empirical data, which are not reproduced by non-relativistic calculations. Relativistic effects are known to be important at high densities, giving an increased repulsion. This leads to a stiffer EOS compared to the EOS derived with a non-relativistic approach. Both the non-relativistic and the relativistic EOS yield values for moment of inertia and redshifts in agreement with the accepted values. The relativistic EOS yields however too large mass and radius. The implications are discussed.
In this work we present results for pairing gaps in β-stable neutron star matter with electrons a... more In this work we present results for pairing gaps in β-stable neutron star matter with electrons and muons using a relativistic Dirac-Brueckner-Hartree-Fock approach, starting with modern mesonexchange models for the nucleon-nucleon interaction. Results are given for superconducting 1 S0 protons and 3 P2 and 1 D2 neutron superfluids. A comparison is made with recent non-relativistic calculations and the implications for neutron star cooling are discussed.
In this work we consider the role of muons in various URCA processes relevant for neutrino emissi... more In this work we consider the role of muons in various URCA processes relevant for neutrino emissions in the core region of neutron stars. The calculations are done for β-stable nuclear matter with and without muons. We find muons to appear at densities ρ = 0.15 fm −3 , slightly around the saturation density for nuclear matter ρ 0 = 0.16 fm −3. The direct URCA processes for nucleons are forbidden for densities below ρ = 0.5 fm −3 , however the modified URCA processes with muons (n + N → p + N + µ + ν µ , p + N + µ → n + N + ν µ), where N is a nucleon, result in neutrino emissivities comparable to those from (n + N → p + N + e + ν e , p + N + e → n + N + ν e). This opens up for further possibilities to explain the rapid cooling of neutrons stars. Superconducting protons reduce however these emissivities at densities below 0.4 fm −3 .
In this work we study properties of neutron star crusts, where matter is expected to consist of n... more In this work we study properties of neutron star crusts, where matter is expected to consist of nuclei surrounded by superfluid neutrons and a homogeneous background of relativistic electrons. The nuclei are disposed in a Coulomb lattice, and it is believed that the structure of the lattice influences considerably the specific heat of the neutronic matter inside the crust of a neutron star. Using a modern meson-exchange potential in the framework of a local-density approximation we calculate the neutronic specific heat accounting for various shapes of the Coulomb lattice, from spherical to non-spherical nuclear shapes. We find that a realistic nucleon-nucleon potential leads to a significant increase in the neutronic specific heat with respect to that obtained assuming a uniform neutron distribution. The increase is largest for the non-spherical phase of the crust. These results may have consequences for the thermal history of young neutron stars.
We present solutions of the coupled, non-relativistic 3 S1-3 D1 gap equations for neutron-proton ... more We present solutions of the coupled, non-relativistic 3 S1-3 D1 gap equations for neutron-proton pairing in symmetric nuclear matter, and estimate relativistic effects by solving the same gap equations modified according to minimal relativity and using single-particle energies from a Dirac-Brueckner-Hartree-Fock calculation. As a main result we find that relativistic effects decrease the value of the gap at the saturation density kF = 1.36 fm −1 considerably, in conformity with the lack of evidence for strong neutron-proton pairing in finite nuclei.
The coherence length of superfluid neutron matter is calculated from the microscopic BCS wavefunc... more The coherence length of superfluid neutron matter is calculated from the microscopic BCS wavefunction of a Cooper pair in momentum space making use of the Bonn meson-exchange potential. We find that the coherence length is proportional to the Fermi momentum-to pairing gap ratio, in good agreement with simple estimates used in the literature, and we establish the appropriate fitting constants using our numerical data. Our calculations can be applied to the problem of inhomogeneous superfluidity of hadronic matter in the crust of a neutron star.
In this work we investigate the so-called model-space Brueckner-Hartree-Fock (MBHF) approach for ... more In this work we investigate the so-called model-space Brueckner-Hartree-Fock (MBHF) approach for nuclear matter as well as for neutron matter and the extension of this which includes the particle-particle and hole-hole (PPHH) diagrams. A central ingredient in the model-space approach for nuclear matter is the boundary momentum k M beyond which the single-particle potential energy is set equal to zero. This is also the boundary of the model space within which the PPHH diagrams are calculated. It has been rather uncertain which value should be used for k M. We have carried out model-space nuclear matter and neutron matter calculations with and without PPHH diagrams for various choices of k M and using several modern nucleon-nucleon potentials. Our results exhibit a saturation region where the nuclear and neutron matter matter energies are quite stable as k M varies. The location of this region may serve to determine an "optimum" choice for k M. However, we find that the strength of the tensor force has a significant influence on binding energy variation with k M. The implications for nuclear and neutron matter calculations are discussed.
We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with... more We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with nucleonic and hyperonic degrees of freedom employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. Only Σ − and Λ are present up to densities ∼ 7ρ 0. The corresponding equations of state are then used to compute properties of neutron stars such as masses and radii.
In this work we calculate the total mass, radius, moment of inertia, and surface gravitational re... more In this work we calculate the total mass, radius, moment of inertia, and surface gravitational redshift for neutron stars using various equations of state (EOS). Modern meson-exchange potential models are used to evaluate the G-matrix for asymmetric nuclear matter. We calculate both a nonrelativistic and a relativistic EOS. Of importance here is the fact that relativistic Brueckner-Hartree-Fock calculations for symmetric nuclear matter fit the empirical data, which are not reproduced by non-relativistic calculations. Relativistic effects are known to be important at high densities, giving an increased repulsion. This leads to a stiffer EOS compared to the EOS derived with a nonrelativistic approach. Both the non-relativistic and the relativistic EOS yield moments of inertia and redshifts in agreement with the accepted values. The relativistic EOS yields, however, too large mass and radius. The implications are discussed.
We present results for the 3 P 2-3 F 2 pairing gap in neutron matter with several realistic nucle... more We present results for the 3 P 2-3 F 2 pairing gap in neutron matter with several realistic nucleon-nucleon potentials, in particular with recent, phase-shift equivalent potentials. We find that their predictions for the gap cannot be trusted at densities above ρ ≈ 1.7ρ 0 , where ρ 0 is the saturation density for symmetric nuclear matter. In order to make predictions above that density, potential models which fit the nucleon-nucleon phase shifts up to about 1 GeV are required.
We study the symmetry energy in infinite nuclear matter employing a non-relativistic Brueckner-Ha... more We study the symmetry energy in infinite nuclear matter employing a non-relativistic Brueckner-Hartree-Fock approach and using various new nucleon-nucleon (NN) potentials, which fit np and pp scattering data very accurately. The potential models we employ are the recent versions of the Nijmegen group, Nijm-I, Nijm-II and Reid93, the Argonne V 18 potential and the CD-Bonn potential. All these potentials yield a symmetry energy which increases with density, resolving a discrepancy that existed for older NN potentials. The origin of remaining differences is discussed.
In this work we calculate neutron and proton energy gaps in neutron star matter, using the Bonn m... more In this work we calculate neutron and proton energy gaps in neutron star matter, using the Bonn meson{exchange interactions and a model{space approach to the gap equation. This approach allows a consistent calculation of energy gaps and single particle energies with the model{space Brueckner{ Hartree{Fock (MBHF) method, without double counting of two{particle correlations. Neutron energy gaps are calculated at zero and nite temperature. Proton energy gaps are calculated at beta equilibrium, and it is shown that the inclusion of muons has a signi cant e ect. The results are compared with those of other works, and the implications for neutron star physics are brie y discussed.
Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine lan... more Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine landslide and flow ahead of the front. Data gathered from different sliding areas highlight some properties of outrunner blocks and in particular their inordinate mobility reflected in runouts of up to 25 kilometres, even on very gentle slopes. Blocks may produce an erosion glide track on the sea floor few centimetres to several metres deep, which in some cases exhibits regularly spaced grooves along the flow direction. Understanding the dynamics of outrunner blocks may shed light on the flow and lubrication of submarine landslides. We develop a simple hydrodynamic model of a rigid block interacting with ambient water and subject to lubrication with the sea floor, and calculate numerically the equation of motion for the block. We find that as a consequence of lift forces and water lubrication, the block may reach long runouts, in agreement with data. When the block is moving at high speed, we find an oscillating solution to the equations of motion which could explain the creation of dashed grooves.
Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine lan... more Outrunner blocks are nearly intact pieces of debris that detach from a slowing-down submarine landslide and flow ahead of the front. Data gathered from different sliding areas highlight some properties of outrunner blocks and in particular their inordinate mobility reflected in runouts of up to 25 kilometres, even on very gentle slopes. Blocks may produce an erosion glide track on the sea floor few centimetres to several metres deep, which in some cases exhibits regularly spaced grooves along the flow direction. Understanding the dynamics of outrunner blocks may shed light on the flow and lubrication of submarine landslides. We develop a simple hydrodynamic model of a rigid block interacting with ambient water and subject to lubrication with the sea floor, and calculate numerically the equation of motion for the block. We find that as a consequence of lift forces and water lubrication, the block may reach long runouts, in agreement with data. When the block is moving at high speed, we find an oscillating solution to the equations of motion which could explain the creation of dashed grooves.
We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with... more We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with nucleonic and hyperonic degrees of freedom, employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. It is found that the only strange baryons emerging in βstable matter up to total baryonic densities of 1.2 fm -3 are Σ -and Λ. The corresponding equations of state are then used to compute properties of neutron stars such as masses and radii.
Deep-sea deposits from submarine landslides, debris flows, and turbidity currents have been recov... more Deep-sea deposits from submarine landslides, debris flows, and turbidity currents have been recovered hundreds of kilometres from inland, even along very gentle seabed slopes (Bugge et al. 1988). This high mobility may be partly explained considering the large sediment volumes associated with submarine mass-wasting. An example is the Storegga landslide on the Norwegian margin, which occurred about 9,000 years ago and ran on an average slope angle of only one degree. With its 3000 km of volume or more, this landslide dwarfs the largest subaerial landslides. Because large landslides usually reach longer horizontal runout than the small ones (the "volume effect"), it seems natural that subaqueous landslides should be more mobile. However, subaqueous landslides appear to be more mobile even when compared to subaerial landslides of the same volume. A better parameter quantifying the flow capacity of a landslide is the runout ratio, defined as the height of fall in the gravity f...
Several submarine debris flows show an apparently chaotic frontal part with blocks of variable si... more Several submarine debris flows show an apparently chaotic frontal part with blocks of variable size (from roughly tens to some hundreds of metres) located some distance beyond the front of the main deposits. This outrunner phenomenon was studied both in the field and in laboratory experiments. Depositional patterns in a field case (Finneidfjord, northern Norway) are classified from the outer distal part of the debris flow to the outermost outrunner block. Similar patterns were found in experimental debris flows, and we suggest that flow processes in the laboratory are applicable to the field example. Theoretical investigations are applied to assess frontal dynamics and especially the formation and motion of outrunner blocks. As the front of the debris flow pushes through ambient water, a combination of front pressure and lift force allows for intrusion of a water layer underneath the front (hydroplaning). This water layer reduces basal friction and induces tensile stresses farther b...
The aim of this work is to study the motion of a rigid streamlined object close to an inclined pl... more The aim of this work is to study the motion of a rigid streamlined object close to an inclined plane. A two-dimensional, small-scale model of a rigid block subjected to gravity is presented combined with the complete dynamical interaction with the surrounding liquid. Both the linear and rotational equations of motion of the body are coupled to the Navier-Stokes equations for the fluid flow using Comsol Multiphysics. A circulation of the fluid around the body is observed, and it generates a strong lift force that is sufficient to keep it completely separated from the bed, while it is travelling down slope. This water lubricating effect, also called hydroplaning has been recognized as an important effect to explain an extraordinary mobility of submarine slides. For the simple shapes studied in this work, we find that the motion becomes unsteady if the densimetric Froude exceeds 0.7.
We present results from many-body calculations for \beta-stable neutron star matter with nucleoni... more We present results from many-body calculations for \beta-stable neutron star matter with nucleonic and hyperonic degrees of freedom, employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. It is found that the only strange baryons emerging in \beta-stable matter up to total baryonic densities of 1.2 fm^{-3} are \Sigma^- and \Lambda. The corresponding equations of state are thence used to compute properties of neutron stars such as the masses, moments of inertia and radii. We also study the possibility of forming a hyperon superfluid and discuss its implications for neutron stars.
In this work we calculate the total mass, radius, moment of inertia, and surface gravitational re... more In this work we calculate the total mass, radius, moment of inertia, and surface gravitational redshift for neutron stars using various equations of state (EOS). The latter are derived from the recent meson-exchange potential models of the Bonn group, and we derive both a non-relativistic and a relativistic EOS. Of importance here is the fact that relativistic Brueckner-Hartree-Fock calculations for symmetric nuclear matter meet the empirical data, which are not reproduced by non-relativistic calculations. Relativistic effects are known to be important at high densities, giving an increased repulsion. This leads to a stiffer EOS compared to the EOS derived with a non-relativistic approach. Both the non-relativistic and the relativistic EOS yield values for moment of inertia and redshifts in agreement with the accepted values. The relativistic EOS yields however too large mass and radius. The implications are discussed.
In this work we present results for pairing gaps in β-stable neutron star matter with electrons a... more In this work we present results for pairing gaps in β-stable neutron star matter with electrons and muons using a relativistic Dirac-Brueckner-Hartree-Fock approach, starting with modern mesonexchange models for the nucleon-nucleon interaction. Results are given for superconducting 1 S0 protons and 3 P2 and 1 D2 neutron superfluids. A comparison is made with recent non-relativistic calculations and the implications for neutron star cooling are discussed.
In this work we consider the role of muons in various URCA processes relevant for neutrino emissi... more In this work we consider the role of muons in various URCA processes relevant for neutrino emissions in the core region of neutron stars. The calculations are done for β-stable nuclear matter with and without muons. We find muons to appear at densities ρ = 0.15 fm −3 , slightly around the saturation density for nuclear matter ρ 0 = 0.16 fm −3. The direct URCA processes for nucleons are forbidden for densities below ρ = 0.5 fm −3 , however the modified URCA processes with muons (n + N → p + N + µ + ν µ , p + N + µ → n + N + ν µ), where N is a nucleon, result in neutrino emissivities comparable to those from (n + N → p + N + e + ν e , p + N + e → n + N + ν e). This opens up for further possibilities to explain the rapid cooling of neutrons stars. Superconducting protons reduce however these emissivities at densities below 0.4 fm −3 .
In this work we study properties of neutron star crusts, where matter is expected to consist of n... more In this work we study properties of neutron star crusts, where matter is expected to consist of nuclei surrounded by superfluid neutrons and a homogeneous background of relativistic electrons. The nuclei are disposed in a Coulomb lattice, and it is believed that the structure of the lattice influences considerably the specific heat of the neutronic matter inside the crust of a neutron star. Using a modern meson-exchange potential in the framework of a local-density approximation we calculate the neutronic specific heat accounting for various shapes of the Coulomb lattice, from spherical to non-spherical nuclear shapes. We find that a realistic nucleon-nucleon potential leads to a significant increase in the neutronic specific heat with respect to that obtained assuming a uniform neutron distribution. The increase is largest for the non-spherical phase of the crust. These results may have consequences for the thermal history of young neutron stars.
We present solutions of the coupled, non-relativistic 3 S1-3 D1 gap equations for neutron-proton ... more We present solutions of the coupled, non-relativistic 3 S1-3 D1 gap equations for neutron-proton pairing in symmetric nuclear matter, and estimate relativistic effects by solving the same gap equations modified according to minimal relativity and using single-particle energies from a Dirac-Brueckner-Hartree-Fock calculation. As a main result we find that relativistic effects decrease the value of the gap at the saturation density kF = 1.36 fm −1 considerably, in conformity with the lack of evidence for strong neutron-proton pairing in finite nuclei.
The coherence length of superfluid neutron matter is calculated from the microscopic BCS wavefunc... more The coherence length of superfluid neutron matter is calculated from the microscopic BCS wavefunction of a Cooper pair in momentum space making use of the Bonn meson-exchange potential. We find that the coherence length is proportional to the Fermi momentum-to pairing gap ratio, in good agreement with simple estimates used in the literature, and we establish the appropriate fitting constants using our numerical data. Our calculations can be applied to the problem of inhomogeneous superfluidity of hadronic matter in the crust of a neutron star.
In this work we investigate the so-called model-space Brueckner-Hartree-Fock (MBHF) approach for ... more In this work we investigate the so-called model-space Brueckner-Hartree-Fock (MBHF) approach for nuclear matter as well as for neutron matter and the extension of this which includes the particle-particle and hole-hole (PPHH) diagrams. A central ingredient in the model-space approach for nuclear matter is the boundary momentum k M beyond which the single-particle potential energy is set equal to zero. This is also the boundary of the model space within which the PPHH diagrams are calculated. It has been rather uncertain which value should be used for k M. We have carried out model-space nuclear matter and neutron matter calculations with and without PPHH diagrams for various choices of k M and using several modern nucleon-nucleon potentials. Our results exhibit a saturation region where the nuclear and neutron matter matter energies are quite stable as k M varies. The location of this region may serve to determine an "optimum" choice for k M. However, we find that the strength of the tensor force has a significant influence on binding energy variation with k M. The implications for nuclear and neutron matter calculations are discussed.
We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with... more We present results from Brueckner-Hartree-Fock calculations for β-stable neutron star matter with nucleonic and hyperonic degrees of freedom employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. Only Σ − and Λ are present up to densities ∼ 7ρ 0. The corresponding equations of state are then used to compute properties of neutron stars such as masses and radii.
Uploads
Papers by Lars Engvik