Hyperon stars at finite temperature in the Brueckner theory

We perform Brueckner-Hartree-Fock calculations of hypernuclear matter at finite temperature and provide convenient analytical parametrizations of the results. We then study the properties of (proto)neutron stars containing hyperons. We find important effects of trapping and finite temperature on the structure of hyperonic stars.

Figure 1

Free energy per baryon, $F/A$, at fixed nucleon density ${\rho }_N=0.6\hspace{0.5em}{\mathrm{fm}}^{-3}$ and lambda fraction ${\rho }_{\Lambda }/{\rho }_N=0.3$, as a function of proton fraction ${\rho }_p/{\rho }_N=0,\dots ,0.5$ and sigma fraction ${\rho }_{\Sigma }/{\rho }_N=0,0.1,0.2,0.3,0.5$ for different temperatures $T=0,10,\dots ,50$ MeV. BHF data (symbols) and fit (curves) are shown.

Figure 2

Relative particle fractions as functions of baryon density in beta-equilibrated matter at entropies $S/A=0,1,2$ without (upper panels) and with (lower panels) hyperons.

Figure 3

Same as Fig. 2, but for neutrino-trapped matter.

Figure 4

Pressure as a function of energy density for beta-equilibrated cold matter (solid curves) and neutrino-trapped hot matter at entropies $S/A=1,2$ (broken curves), without (upper curves), and with (lower curves) hyperons. The case with free hyperons at $T=0$ (green curve) is also displayed.

Figure 5

Gravitational mass (in units of the solar mass $M_{\odot }=1.98\times {10}^{33}$$g$) as a function of radius (left panel) and central baryon density (right panel) for cold NSs (solid curves) and neutrino-trapped PNSs at entropies $S/A=1,2$ (broken curves). The thick (thin) curves describe configurations with (without) hyperons.