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

We explore the effects of strangeness and Δ resonance in baryonic matter and compact stars within the relativistic-mean-field models. The parameter set 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 Δ-meson couplings. In light of the recent observations of GW170817 with the dimensionless combined tidal deformability 197≤Λ̄≤720, we find it is essential to include the Δ resonances in compact stars, and small Δ-ρ coupling gρΔ is favored if the mass 2.27-0.15+0.17 M of PSR J2215+5135 is confirmed.