The Masses of Isolated Neutron Stars Inferred from the Gravitational Redshift Measurements

Understand

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.
• For most INSs, no mass measurements are possible for NICER because of observational limitations.