Evidence for a maximum mass cut-off in the neutron star mass distribution and constraints on the equation of state

By Justin Alsing, Hector O. Silva, Emanuele Berti. 2017

195 citations recorded by the source corpus.

We infer the mass distribution of neutron stars in binary systems using a flexible Gaussian mixture model and use Bayesian model selection to explore evidence for multi-modality and a sharp cut-off in the mass distribution. We find overwhelming evidence for a bimodal distribution, in agreement with previous literature, and report for the first time positive evidence for a sharp cut-off at a maximum neutron star mass. We measure the maximum mass to be $2.0M_\odot 2M_\odot$ neutron stars, our inference of $m_\mathrm{max}$ is able to distinguish between models at odds ratios of up to $12:1$, whilst under a flexible piecewise polytropic equation of state model our maximum mass measurement improves constraints on the pressure at $3-7\times$ the nuclear saturation density by $\sim 30-50\%$ compared to simply requiring $m_\mathrm{max}> 2M_\odot$. We obtain a lower bound on the maximum sound speed attained inside the neutron star of $c_s^\mathrm{max} > 0.63c$ (99.8\%), ruling out $c_s^\mathrm{max} < c/\sqrt{3}$ at high significance. Our constraints on the maximum neutron star mass strengthen the case for neutron star-neutron star mergers as the primary source of short gamma-ray bursts.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/baeca11471450d212b45d3cabc926ffe678599e4

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In Astronomy and Astrophysics

1. Michela Mapelli
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Citations in the corpus

• GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run (2020, methodology): “The mass of the secondary component is consistent with masses of (previously) reported neutron stars [10,271,272,274], but the data are uninformative about potential tidal effects, showing essentially no difference between the prior and posterior on Λ2 obtained from NSBH waveforms SEOBNRv4_ROM_ NRTi”
• Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M ⊙ Compact Object and a Neutron Star (2024, background): “The mass of the secondary is consistent with the distribution of known neutron star masses, including Galactic pulsars (Antoniadis et al. 2016; Alsing et al. 2018; ¨Ozel & Freire 2016; Farrow et al. 2019) and extragalactic GW observations (Landry & Read 2021; Abbott et al. 2023b).”
• The Mass Distribution of Galactic Double Neutron Stars (2019, background): “As in Alsing et al. (2018), we ignore the measurement uncertainty of mass function to derive the last line in Equation (2).”
• Constraining the Dense Matter Equation of State with Joint Analysis of NICER and LIGO/Virgo Measurements (2019, result): “We find that the maximum mass distribution presented here is broadly consistent with values found in other works (see, e.g., Margalit & Metzger 2017; Shibata et al. 2017; Alsing et al. 2018; Rezzolla et al. 2018; Ruiz et al. 2018; Tews & Schwenk 2020).”
• Constraining the Speed of Sound inside Neutron Stars with Chiral Effective Field Theory Interactions and Observations (2018, result): “For the current maximum mass constraint, Mmax=2Me, c 0.4S,max 2 for ntr,2, which is in excellent agreement with the findings of Alsing et al. (2018).”