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General Relativity and Quantum Cosmology, gr-qc, Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
The Neutron Star Interior Composition Explorer (NICER) recently measured the
mass and equatorial radius of the isolated neutron star PSR J0030+0451. We use
these measurements to infer the moment of inertia, the quadrupole moment, and
the surface eccentricity of an isolated neutron star for the first time, using
relations between these quantities that are insensitive to the unknown equation
of state of supranuclear matter. We also use these results to forecast the
moment of inertia of neutron star A in the double pulsar binary J0737-3039, a
quantity anticipated to be directly measured in the coming decade with radio
observations. Combining this information with the measurement of the tidal Love
number with LIGO/Virgo observations, we propose and implement the first
theory-agnostic and equation-of-state-insensitive test of general relativity.
Specializing these constraints to a particular modified theory, we find that
consistency with general relativity places the most stringent constraint on
gravitational parity violation to date, surpassing all other previously
reported bounds by seven orders of magnitude and opens the path for future a
test of general relativity with multimessenger neutron star observations.
