THE DENSE MATTER EQUATION OF STATE FROM NEUTRON STAR RADIUS AND MASS MEASUREMENTS

By F. Özel, Dimitrios Psaltis, T. Güver, G. Baym, C. Heinke, S. Guillot. 2015

236 citations recorded by the source corpus.

We present a comprehensive study of spectroscopic radius measurements of twelve neutron stars obtained during thermonuclear bursts or in quiescence. We incorporate, for the first time, a large number of systematic uncertainties in the measurement of the apparent angular sizes, Eddington fluxes, and distances, in the composition of the interstellar medium, and in the flux calibration of X-ray detectors. We also take into account the results of recent theoretical calculations of rotational effects on neutron star radii, of atmospheric effects on surface spectra, and of relativistic corrections to the Eddington critical flux. We employ Bayesian statistical frameworks to obtain neutron star radii from the spectroscopic measurements as well as to infer the equation of state from the radius measurements. Combining these with the results of experiments in the vicinity of nuclear saturation density and the observations of ∼ 2 M ⊙ ?> neutron stars, we place strong and quantitative constraints on the properties of the equation of state between ≈ 2 – 8 ?> times the nuclear saturation density. We find that around M = 1.5 M ⊙ , ?> the preferred equation of state predicts radii between 10.1 and 11.1 km. When interpreting the pressure constraints in the context of high density equations of state based on interacting nucleons, our results suggest a relatively weak contribution of the three-body interaction potential.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/aa38780bbc987caa0799e40f3e79c8c7669bd74f

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Geophysics

Citations in the corpus

Constraining the mass and radius of neutron stars in globular clusters (2017, methodology): “…a preferred radius between 10.1 and 11.1 km. Finally, Bogdanov et al. (2016) obtained new constraints on the mass and radius of the quiescent LMXBs X7 and X5 in 47 Tuc, and combined these constraints with the results of Özel et al. (2016) to find a preferred radius in the range 9.9-11.2 km.”
Constraining the Maximum Mass of Neutron Stars from Multi-messenger Observations of GW170817 (2017, methodology): “A low value of Mmax has also been suggested based on Galactic NS radius measurements (Özel et al. 2016; Özel & Freire 2016) and would be consistent with the relatively small NS radius .”
Gravitational waves from neutron star mergers and their relation to the nuclear equation of state (2019, background): “may signicantly introduce systematic errors [519]. 35 Refs. [360, 553, 275] combined the GW measurement with electromagnetic observations of other NSs in accreting low-mass x-ray binaries (from Ref. [554]) to give a more precise estimate of the tidal deformability and Ref. [254] proposed an aordable”
Equation of state sensitivities when inferring neutron star and dense matter properties (2018, methodology): “…stars seems to favour radii in the range of 9–13 km (see e.g. Steiner, Lattimer & Brown 2013; Bogdanov et al. 2016; Nättilä et al. 2016, 2017; Özel et al. 2016; Shaw et al. 2018), although the methods are heavily affected by systematics that are still to be resolved (see e.g. Watts et…”
Evidence for a maximum mass cut-off in the neutron star mass distribution and constraints on the equation of state (2017, methodology): “Whilst there is not yet firm consensus amongst NS radii measurements, advances have been made in accounting for systematic errors and strong (although model dependent) constraints on the EoS have been obtained (see eg., Özel et al. (2016) for an attempt to account for a multitude of systematics).”
Unified equation of state for neutron stars on a microscopic basis (2015, result): “For a NS of 1.5 solar masses, the BCPM EoS predicts a radius of 11.63 km (see Table 10), in line with the recent analysis shown in Ozel et al. (2015); see also Chen & Piekarewicz (2015).”
From hadrons to quarks in neutron stars: a review (2017, methodology): “We turn now to the implications of the unified construction of the equation of state (QHC18) on astrophysical properties of neutron stars, and the constraints indicated by current observations, notably the measurements of the two neutron stars with masses ∼ 2M [41, 42], early inferences of the mass-”
Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra (2017, methodology): “Hence, if all of the M−R solutions from multiple sources are located only at this line (see Özel et al. 2016, for such a situation), it either means that the model is applied inconsistently to data that it does not describe, or that all NSs happen to have the same compactness M/R = c2/4G.”
A NICER View of PSR J0030+0451: Implications for the Dense Matter Equation of State (2019, methodology): “Bogdanov et al. (2016) and Özel et al. (2016) used a piecewisepolytropic EoS model, inferring both EoS parameters and the associated mass–radius bands.”