Hypernuclei and massive neutron stars

Fortin, M.; Avancini, S. S.; Providência, Constança; Vidaña, Isaac

doi:10.1103/physrevc.95.065803

Cited by 127 publications

(128 citation statements)

References 134 publications

(163 reference statements)

Supporting

Mentioning

122

Contrasting

Order By: Relevance

“…(ii) Throughout our work we have focused on a ΛΞ − hyperon composition. For a number of EoS models, Σ − appears in the core (for instance, in deep layers of massive NL3ωρ and FSU2H stars; see also [21][22][23]). The relation between ζ and λ inferred in Sec.…”

Section: Discussionmentioning

confidence: 99%

Bulk viscosity in neutron stars with hyperon cores

et al. 2019

Self Cite

View full text Add to dashboard Cite

It is well-known that r-mode oscillations of rotating neutron stars may be unstable with respect to the gravitational wave emission. It is highly unlikely to observe a neutron star with the parameters within the instability window, a domain where this instability is not suppressed. But if one adopts the 'minimal' (nucleonic) composition of the stellar interior, a lot of observed stars appear to be within the r-mode instability window. One of the possible solutions to this problem is to account for hyperons in the neutron star core. The presence of hyperons allows for a set of powerful (leptonfree) non-equilibrium weak processes, which increase the bulk viscosity, and thus suppress the r-mode instability. Existing calculations of the instability windows for hyperon NSs generally use reaction rates calculated for the Σ − Λ hyperonic composition via the contact W boson exchange interaction. In contrast, here we employ hyperonic equations of state where the Λ and Ξ − are the first hyperons to appear (the Σ − 's, if they are present, appear at much larger densities), and consider the meson exchange channel, which is more effective for the lepton-free weak processes. We calculate the bulk viscosity for the non-paired npeµΛΞ − matter using the meson exchange weak interaction. A number of viscosity-generating non-equilibrium processes is considered (some of them for the first time in the neutron-star context). The calculated reaction rates and bulk viscosity are approximated by simple analytic formulas, easy-to-use in applications. Applying our results to calculation of the instability window, we argue that accounting for hyperons may be a viable solution to the r-mode problem.PACS numbers:

show abstract

Section: Discussionmentioning

confidence: 99%

Bulk viscosity in neutron stars with hyperon cores

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The relative stability of x sΞ to the modification of the nucleonic EoS, for each considered scenario, reflects the relatively small dispersion among the considered EoS, over the subsaturation density domain explored by a hyperon bound in a nucleus. Note that a similar situation corresponds, according to [8][9][10], also to x sΛ and the explication is the same.…”

Section: B Hyperonic Eos With Calibrated Meson Couplingsmentioning

confidence: 91%

Relativistic hypernuclear compact stars with calibrated equations of state

et al. 2020

View full text Add to dashboard Cite

Within the covariant density functional theory of hypernuclear matter we build a series of equations of state for hypernuclear compact stars, by calibrating the coupling constants of the Ξ-hyperon to the experimental binding energy of the single-Ξ hypernuclei 15 Ξ − C and 12 Ξ − Be. Coupling constants of the Λ-hyperon to nucleons have been calibrated on a vast collection of experimental data on single Λ-hypernuclei and we employ those values. Uncertainties on the couplings of the Σ-hyperon to nuclear matter, due to lack of experimental data, are accounted for by allowing for a wide variation of the well depth of Σ at rest in symmetric saturated nuclear matter. To account for uncertainties in the nucleonic sector at densities much larger than n 0 , a rich collection of parametrizations is employed, some of them in agreement with existing constraints from nuclear physics and astrophysics. Neutron star properties are investigated with all these calibrated equations of state. The effects of the presence of hyperons on the radius, on the tidal deformability, on the moment of inertia, and on the nucleonic direct Urca process are discussed. The sensitivity of the hyperonic direct Urca processes to uncertainties in the nucleonic and hyperonic sectors is also addressed. It is shown that the relative variations of the radius, tidal deformability and moment of inertia from the values that characterize purely nucleonic stars are linearly correlated with the strangeness fraction. The maximum radius deviation, obtained for most massive neutron stars, is ≈ 10%. The reduction of the maximum mass, triggered by nucleation of strangeness, is estimated at ≈ 15 − 20%, out of which 5% comes from insufficient information on the Σ-hyperon interactions. A total of 44 calibrated hyperonic equations of state are published as Supplemental Material.

show abstract

“…Without the coupling to σ * , the Y Y interaction is very repulsive already at low densities. We obtain U ( ) (n sat /5) = 7 MeV, U ( ) (n sat /5) = 47 MeV, and U ( ) (n sat /5) = 26 MeV, whereas the data on double--hypernuclei suggest a weakly attractive potential at least for hyperons, U ( ) (n sat /5) ≈ −1 to −5 MeV [73,75,76]. Although, as shown, e.g., in Refs.…”

Section: B Homogeneous Mattermentioning

confidence: 94%

“…We will assume here standard values [40,70,73] in symmetric nuclear matter at saturation density n sat : U (N) (n sat ) = −30 MeV, U (N) (n sat ) = −18 MeV, and U (N) (n sat ) = +30 MeV. The resulting values are in the range obtained by calculating directly properties of single hypernuclei; see Refs.…”

Section: B Homogeneous Mattermentioning

confidence: 99%

See 1 more Smart Citation

New temperature dependent hyperonic equation of state: Application to rotating neutron star models and I−Q relations

et al. 2017

View full text Add to dashboard Cite

In this work we present a newly constructed equation of state (EoS), applicable to stellar core collapse and neutron star mergers including the entire baryon octet. Our EoS is compatible with the main constraints from nuclear physics and, in particular, with a maximum mass for cold β-equilibrated neutron stars of 2M in agreement with recent observations. As an application of our new EoS, we compute numerical stationary models for rapidly (rigidly) rotating hot neutron stars. We consider maximum masses of hot stars, such as protoneutron stars or hypermassive neutron stars in the postmerger phase of binary neutron star coalescence. The universality of I -Q relations at nonzero temperature for fast rotating models, comparing a purely nuclear EoS with its counterparts containing hyperons or the entire baryon octet, respectively, is discussed, too. We find that the I -Q universality is broken in our models when thermal effects become important, independent on the presence of entropy gradients. Thus, the use of I -Q relations for the analysis of protoneutron stars or merger remnant data, including gravitational wave signals from the last stages of binary neutron star mergers, should be regarded with care.

show abstract

Hypernuclei and massive neutron stars

Cited by 127 publications

References 134 publications

Bulk viscosity in neutron stars with hyperon cores

Bulk viscosity in neutron stars with hyperon cores

Relativistic hypernuclear compact stars with calibrated equations of state

New temperature dependent hyperonic equation of state: Application to rotating neutron star models and I−Q relations

Contact Info

Product

Resources

About