A Population-Informed Mass Estimate for Pulsar J0740+6620
Will M. Farr, Katerina Chatziioannou
Abstract
Abstract Galactic double neutron star systems have a tight mass distribution around ∼1.35 M ⊙ , but the mass distribution of all known pulsars is broader (Tauris et al. 2017). Here we reconstruct the Alsing et al. (2018), Antoniadis et al. (2016) bimodal mass distribution of pulsars observed in binary systems, incorporating data from observations of J0740+6620 which were not available at the time of those works. Because J0740+6620 is an outlier in the mass distribution with non-negligible uncertainty in its mass measurement, its mass receives a large correction from the population, becoming <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">J</mml:mi> <mml:mn>0740</mml:mn> <mml:mo>+</mml:mo> <mml:mn>6620</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2.03</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.08</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.10</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> (median and 68% CI). Stochastic samples from our population model, including population-informed pulsar mass estimates, are available at https://github.com/farr/AlsingNSMassReplication and archived at Farr & Chatziioannou (2020).