The masses of isolated neutron stars inferred from the gravitational redshift measurements. (arXiv:1911.08107v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tang_S/0/1/0/all/0/1">Shao-Peng Tang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jiang_J/0/1/0/all/0/1">Jin-Liang Jiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_W/0/1/0/all/0/1">Wei-Hong Gao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fan_Y/0/1/0/all/0/1">Yi-Zhong Fan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wei_D/0/1/0/all/0/1">Da-Ming Wei</a>
For some neutron stars (NSs) in the binary systems, the masses have been
accurately measured. While for the isolated neutron stars (INSs), no mass
measurement has been reported yet. The situation will change soon thanks to the
successful performance of the Neutron Star Interior Composition Explorer
(NICER), with which the radius and mass of the isolated PSR J0030+0451 can be
simultaneously measured. Anyhow, for most INSs, no mass measurements are
possible for NICER because of the observational limitations. Benefited from the
recent significant progress made on constraining the equation of state (EoS) of
NSs, in this work we propose a way to estimate the masses of the INSs with the
measured gravitational redshifts. We apply our method to RX J1856.5-3754, RX
J0720.4-3125, and RBS 1223, three members of “The Magnificent Seven” (M7), and
estimate their masses to be $1.24_{-0.29}^{+0.29}M_{odot}$,
$1.23_{-0.05}^{+0.10}M_{odot}$, and $1.08_{-0.11}^{+0.20}M_{odot}$,
respectively. These masses are consistent with that of binary neutron star
(BNS) systems, suggesting no evidence for experiencing significant accretion of
these isolated objects.
For some neutron stars (NSs) in the binary systems, the masses have been
accurately measured. While for the isolated neutron stars (INSs), no mass
measurement has been reported yet. The situation will change soon thanks to the
successful performance of the Neutron Star Interior Composition Explorer
(NICER), with which the radius and mass of the isolated PSR J0030+0451 can be
simultaneously measured. Anyhow, for most INSs, no mass measurements are
possible for NICER because of the observational limitations. Benefited from the
recent significant progress made on constraining the equation of state (EoS) of
NSs, in this work we propose a way to estimate the masses of the INSs with the
measured gravitational redshifts. We apply our method to RX J1856.5-3754, RX
J0720.4-3125, and RBS 1223, three members of “The Magnificent Seven” (M7), and
estimate their masses to be $1.24_{-0.29}^{+0.29}M_{odot}$,
$1.23_{-0.05}^{+0.10}M_{odot}$, and $1.08_{-0.11}^{+0.20}M_{odot}$,
respectively. These masses are consistent with that of binary neutron star
(BNS) systems, suggesting no evidence for experiencing significant accretion of
these isolated objects.
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