Constraining the mass and radius of neutron stars in globular clusters

By A. Steiner, C. Heinke, S. Bogdanov, C. Li, W. Ho, A. Bahramian, U. S.HanTennessee, Oak Ridge Natl. Lab., P. D. U. O. Alberta, Columbia and 4 more. 2017

132 citations recorded by the source corpus.

We analyze observations of eight quiescent low-mass X-ray binaries in globular clusters and combine them to determine the neutron star mass-radius curve and the equation of state of dense matter. We determine the effect that several uncertainties may have on our results, including uncertainties in the distance, the atmosphere composition, the neutron star maximum mass, the neutron star mass distribution, the possible presence of a hotspot on the neutron star surface, and the prior choice for the equation of state of dense matter. The distance uncertainty is implemented in a new Gaussian blurring method which can be directly applied to the probability distribution over mass and radius.We find that the radius of a 1.4 solar mass neutron star is most likely from 10 to 14 km and that tighter constraints are only possible with stronger assumptions about the nature of the neutron stars, the systematics of the observations, or the nature of dense matter. Strong phase transitions in the equation of state are preferred, and in this case, the radius is likely smaller than 12 km. However, radii larger than 12 km are preferred if the neutron stars have uneven temperature distributions.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/125997b62d12945714e666377257c897d8cb0451

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In Astronomy and Astrophysics

1. J. Lattimer
2. A. Watts
3. Dimitrios Psaltis
4. S. Guillot
5. F. Özel
6. I. Tews
7. M. Miller
8. A. Schwenk

Citations in the corpus

• Constraining the Neutron Star Mass–Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-Ray Data Set (2019, methodology): “…precise measurements there are enough concerns about systematic errors that it is not yet possible to constrain the EoS significantly (see, e.g., Steiner et al. 2010, 2018; Leahy et al. 2011; Guillot et al. 2013; Heinke et al. 2014; Miller & Lamb 2016; Özel et al. 2016; Nättilä et al. 2017).”
• Constraining the Speed of Sound inside Neutron Stars with Chiral Effective Field Theory Interactions and Observations (2018, result): “We found that the upper limit on the maximum mass of NSs is 2.9–3.5Me, and that radii for typical 1.4Me NSs range between 10 and 14 km, in agreement with the results of Hebeler et al. (2013) and Steiner et al. (2018).”
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter (2019, methodology): “Various radius estimates have been made using models of the X-ray emission from quiescent neutron stars (see Steiner et al. 2018 for a recent summary), from neutron stars during thermonuclear X-ray bursts (see Steiner et al. 2010; Özel et al. 2016; and Nättilä et al. 2017 for different…”
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation (2019, background): “Steiner et al. (2018) considered the effects of pile-up on qLMXB spectra, the possibility of pure helium atmospheres (instead of pure hydrogen atmospheres), as well as non-uniform surface temperature distributions.”
• A NICER View of PSR J0030+0451: Implications for the Dense Matter Equation of State (2019, background): “Steiner et al. (2010, 2013, 2018) and Lattimer & Steiner (2014) considered a larger range of parameterized EoS models to infer dense matter parameters including those associated with the nuclear symmetry energy and the mass–radius bands.”