Relativistic description of dense matter equation of state and compatibility with neutron star observables: a Bayesian approach

Abstract

The general behavior of the nuclear equation of state (EOS), relevant for the description of neutron stars (NS), is studied within a Bayesian approach applied to a set of models based on a density dependent relativistic mean field description of nuclear matter. The EOS is subjected to a minimal number of constraints based on nuclear saturation properties and the low density pure neutron matter EOS obtained from a precise next-to-next-to-next-to-leading order (N 3 LO) calculation in chiral effective field theory (χEFT). The posterior distributions of the model parameters obtained under these minimal constraints are employed to construct the distributions of various nuclear matter properties and NS properties such as radii, tidal deformabilites, central energy densities and speeds of sound etc. We found that 90% confidence interval (CI) for allowed NS mass -radius relationship and tidal deformabilites are compatible with GW170817 and recent NICER observations, without invoking the exotic degrees of freedom.

Astrophysical implications on hyperon couplings and hyperon star properties with relativistic equations of states

“…The objective of the present study is to confront the phenomenological hyperonic interaction to the recently observed neutron star properties (like mass M , radius R and tidal deformability Λ), and perform Bayesian inference for the hyperon-meson coupling constants from the robust LIGO/Virgo tidal measurement of the GW170817 binary neutron star merger (Abbott et al 2017) 1 as well as two NICER mass-radius measurements of pulsars [PSR J0030+0451 (Riley et al 2019;Miller et al 2019) and PSR J0740+6620 (Riley et al 2021;Miller et al 2021)]. Previously, such kind of Bayesian analysis on nuclear matter parameters has been performed in, e.g., Traversi & Char (2020); Imam et al (2022); Malik et al (2022), we here focus on the hypernuclear matter based on a set of six generally-used relativistic mean-field (RMF) Lagrangians. We consider two different classes of the RMF models, one with constant couplings and nonlinear meson terms in the Lagrangian [NL3ωρ (Horowitz & Piekarewicz 2001), PK1 (Long et al 2004)] and a second one without these terms but introducing density-dependent coupling strengths [DD-LZ1 (Wei et al 2020), DD-ME2 (Lalazissis et al 2005), DD2 (Typel et al 2010), PKDD (Long et al 2004)], which all treat effectively the in-medium properties of baryon-baryon interaction.…”

High-Density behavior of symmetry energy and speed of sound in the dense matter within an effective chiral model

“…6, we plot the density dependence of symmetry energy curvature parameter K sym against baryon number density for all of our different models corresponding to different symmetry energy(J 1 ). We also compare the range of K sym at saturation density K sym,0 ∈ [−177, 71] MeV obtained from RMF within the Bayesian Inference approach with the minimal constraint imposed [26,74]. All of our models show good agreement with the value at saturation density except the model with J 1 = 25.2 MeV.…”

“…Based on the current knowledge of nuclear masses and giant dipole polarizability, the symmetry energy has been constrained J 0 32.25 ± 2.5 MeV [16][17][18][19] and it's slope parameter L 0 58.9 ± 16 MeV [4,[20][21][22][23][24] at nuclear saturation density. However, there are very few known theoretical constraints on K sym,0 and constraints on Q sym,0 [24][25][26] and therefore, one of our objectives here is to analyze their interdependence with a model based on microphysics. Numerous relativistic mean-field models (RMF) [27][28][29][30][31] are known to have been successfully applied theoretically to extract finite nuclear properties across the periodic table as well as in applications of nuclear matter.…”

Compact Binary Coalescences: Astrophysical Processes and Lessons Learned

“…The secondary of GW190814 might be either a BH or a NS. The non-detection of any electromagnetic counterparts [475][476][477][478][479][480][481][482][483][484][485], the fact that there were neither clear signatures of tides or spin-induced quadrupole effects in the waveform [486,487], and the uncertainties on both the theoretical estimates of the maximum NS mass and the NS equation of state [488][489][490][491], prevent us to determine the nature of the compact object. Post-merger electromagnetic studies suggest that the merger product of GW170817 likely collapsed into a (highly-spinning) BH with a mass comparable to GW190814's secondary (∼2.6 M ) [492].…”