2020MNRAS.499.4526W -
Mon. Not. R. Astron. Soc., 499, 4526-4533 (2020/December-2)
What if the neutron star maximum mass is beyond ∼2.3 M☉?
WU X.H., DU S. and XU R.X.
Abstract (from CDS):
By assuming the formation of a black hole soon after the merger event of GW170817, the maximum mass of non-rotating stable neutron star, MTOV ≃ 2.3 M☉, is proposed by numerical relativity, but there is no solid evidence to rule out MTOV > 2.3 M☉ from the point of both microphysical and astrophysical views. It is naturally expected that the equation of state (EOS) would become stiffer beyond a specific density to explain massive pulsars. We consider the possibility of EOSs with MTOV > 2.3 M☉, investigating the stiffness and the transition density in a polytropic model, for two kinds of neutron stars (i.e. gravity-bound and strong-bound stars on surface). Only two parameters are input in both cases: (ρt, γ) for gravity-bound neutron stars, while (ρs, γ) for strong-bound strange stars, with ρt the transition density, ρs the surface density, and γ the polytropic exponent. In the matter of MTOV > 2.3 M☉ for the maximum mass and 70 <= Λ1.4 <= 580 for the tidal deformability, it is found that the smallest ρt and γ should be ∼0.50 ρ0 and ∼2.65 for neutron stars, respectively, whereas for strange star, we have γ > 1.40 if ρs > 1.0 ρ0 (ρ0 is the nuclear saturation density). These parametric results could guide further research of the real EOS with any foundation of microphysics if a pulsar mass higher than 2.3 M☉ is measured in the future, especially for an essential comparison of allowed parameter space between gravity-bound and strong-bound compact stars.
Abstract Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
equation of state - stars: neutron - pulsars: general
Simbad objects:
6
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