hide
Free keywords:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc,Nuclear Theory, nucl-th
Abstract:
Instead of parameterizing the pressure-density relation of a neutron star
(NS), one can parameterize its macroscopic properties such as mass ($M$),
radius ($R$), and dimensionless tidal deformability ($\Lambda$) to infer the
equation of state (EoS) combining electromagnetic and gravitational wave (GW)
observations. We present a new method to parameterize $R(M)$ and $\Lambda(M)$
relations, which approximate the candidate EoSs with accuracy better than 5\%
for all masses and span a broad region of $M-R-\Lambda$ plane. Using this
method we combine the $M-\Lambda$ measurement from GW170817 and GW190425, and
simultaneous $M-R$ measurement of PSR J0030+0451 and PSR J0740+6620 to place
joint constraints on NS properties. At 90 \% confidence, we infer
$R_{1.4}=12.05_{-0.87}^{+0.98}$ km and $\Lambda_{1.4}=372_{-150}^{+220}$ for a
$1.4 M_{\odot}$ NS, and $R_{2.08}=12.65_{-1.46}^{+1.36}$ km for a $2.08
M_{\odot}$ NS. Furthermore, we use the inferred values of the maximum mass of a
nonrotating NS $M_{\rm max}=2.52_{-0.29}^{+0.33} M_{\odot}$ to investigate the
nature of the secondary objects in three potential neutron star-black hole
merger (NSBH) system.
