Strangeness and Δ resonance in compact stars with relativistic-mean-field models

Abstract

We explore the effects of strangeness and ∆ resonance in baryonic matter and compact stars within the relativistic-mean-field (RMF) models. The covariant density functional PKDD is adopted for N -N interaction, parameters fixed based on finite hypernuclei and neutron stars are taken for the hyperon-meson couplings, and the universal baryon-meson coupling scheme is adopted for the ∆meson couplings. In light of the recent observations of GW170817 with the dimensionless combined tidal deformability 197 ≤Λ ≤ 720, we find it is essential to include the ∆ resonances in compact stars, and small ∆-ρ coupling gρ∆ is favored if the mass 2.27 +0.17 −0.15 M of PSR J2215+5135 is confirmed.

Neutron-star tidal deformability and equation-of-state constraints

“…7), astronomical observations can also be used to place constraints on the relevant parameter space. In general, since GW170817 provided an upper limit onΛ, any physical effect that results in a softening of the equation of state can be consistent with the data [88,[240][241][242][243][244][245][246] As such, a strong first-order phase transition might make an equation of state model compatible with the GW170817 data, even if the hadronic part on its own is not [152,[247][248][249][250]. A number of studies have constructed models that can successfully interpret the inspiral signal from GW170817 as the coalescence of any combination of hadronic and hybrid hadronic-quark neutron stars and place corresponding constraints on the relevant model parameter space [149,247,248,[251][252][253][254][255][256][257][258][259][260].…”

“…Progress in the intervening years has been rapid, establishing gravitational waves as a promising input for nuclear models, which are now routinely tuned and compared to GW170817, e.g. [245,[315][316][317][318][319][320][321][322]. The continued observational campaigns and sensitivity improvements [141] as well as the addition of new planned or proposed detectors [75-77, 323, 324] in the global gravitational wave detector network both opens up unique opportunities and brings novel challenges to the surface.…”

A bag model of matter condensed by the strong interaction

“…2. Does strangeness play an important role [14][15][16][17][18][19][20][21][22][23][24][25][26][27]? Normal atomic nucleus is 2-flavoured (u and d), but "giant nucleus" at supra-nuclear densities may very well lie in the regime of 3-flavours of quarks (u, d, and s).…”

Anisotropic neutron stars with hyperons: implication of the recent nuclear matter data and observations of neutron stars

“…The recent reports on the role of hyperons and other exotics and how to deal with the "hyperon puzzle" can be found, e.g., in Refs. [57][58][59][60][61][62][63][64][65][66][67][68] and also see the references therein.…”