Merger of a Neutron Star with a Black Hole: one-family vs. two-families scenario

Understand

A kilonova signal is generally expected after a Black Hole - Neutron Star merger.

• The strength of the signal is related to the equation of state of neutron star matter and it increases with the stiffness of the latter.
• The recent results obtained by NICER from the analyses of PSR J0740+6620 suggest a rather stiff equation of state and the expected kilonova signal is therefore strong, at least if the mass of the Black Hole does not exceed $\sim 10 \mathrm{\,M}_\odot$ and if the adimensional spin parameter is not too small and the orbit is prograde.
• We compare the predictions obtained by considering equations of state of neutron star matter satisfying the most recent observations and assuming that only one family of compact stars exists with the results predicted in the two-families scenario.