Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs

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Hauptverfasser: Rutherford, Nathan, Mendes, Melissa, Svensson, Isak, Schwenk, Achim, Watts, Anna L., Hebeler, Kai, Keller, Jonas, Prescod-Weinstein, Chanda, Choudhury, Devarshi, Raaijmakers, Geert, Salmi, Tuomo, Timmerman, Patrick, Vinciguerra, Serena, Guillot, Sebastien, Lattimer, James M.
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Veröffentlicht: 2024
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author Rutherford, Nathan
Mendes, Melissa
Svensson, Isak
Schwenk, Achim
Watts, Anna L.
Hebeler, Kai
Keller, Jonas
Prescod-Weinstein, Chanda
Choudhury, Devarshi
Raaijmakers, Geert
Salmi, Tuomo
Timmerman, Patrick
Vinciguerra, Serena
Guillot, Sebastien
Lattimer, James M.
author_facet Rutherford, Nathan
Mendes, Melissa
Svensson, Isak
Schwenk, Achim
Watts, Anna L.
Hebeler, Kai
Keller, Jonas
Prescod-Weinstein, Chanda
Choudhury, Devarshi
Raaijmakers, Geert
Salmi, Tuomo
Timmerman, Patrick
Vinciguerra, Serena
Guillot, Sebastien
Lattimer, James M.
contents Pulse profile modeling of X-ray data from NICER is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory ($χ$EFT), and masses and tidal deformabilities inferred from gravitational wave detections of binary neutron star mergers, this has lead to a steady improvement in our understanding of the dense matter equation of state (EOS). Here we consider the impact of several new results: the radius measurement for the 1.42$\,M_\odot$ pulsar PSR J0437$-$4715 presented by Choudhury et al. (2024), updates to the masses and radii of PSR J0740$+$6620 and PSR J0030$+$0451, and new $χ$EFT results for neutron star matter up to 1.5 times nuclear saturation density. Using two different high-density EOS extensions -- a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS) -- we find the radius of a 1.4$\,M_\odot$ (2.0$\,M_\odot$) neutron star to be constrained to the 95% credible ranges $12.28^{+0.50}_{-0.76}\,$km ($12.33^{+0.70}_{-1.34}\,$km) for the PP model and $12.01^{+0.56}_{-0.75}\,$km ($11.55^{+0.94}_{-1.09}\,$km) for the CS model. The maximum neutron star mass is predicted to be $2.15^{+0.14}_{-0.16}\,$$M_\odot$ and $2.08^{+0.28}_{-0.16}\,$$M_\odot$ for the PP and CS model, respectively. We explore the sensitivity of our results to different orders and different densities up to which $χ$EFT is used, and show how the astrophysical observations provide constraints for the pressure at intermediate densities. Moreover, we investigate the difference $R_{2.0} - R_{1.4}$ of the radius of 2$\,M_\odot$ and 1.4$\,M_\odot$ neutron stars within our EOS inference.
format Preprint
id arxiv_https___arxiv_org_abs_2407_06790
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs
Rutherford, Nathan
Mendes, Melissa
Svensson, Isak
Schwenk, Achim
Watts, Anna L.
Hebeler, Kai
Keller, Jonas
Prescod-Weinstein, Chanda
Choudhury, Devarshi
Raaijmakers, Geert
Salmi, Tuomo
Timmerman, Patrick
Vinciguerra, Serena
Guillot, Sebastien
Lattimer, James M.
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Nuclear Experiment
Nuclear Theory
Pulse profile modeling of X-ray data from NICER is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory ($χ$EFT), and masses and tidal deformabilities inferred from gravitational wave detections of binary neutron star mergers, this has lead to a steady improvement in our understanding of the dense matter equation of state (EOS). Here we consider the impact of several new results: the radius measurement for the 1.42$\,M_\odot$ pulsar PSR J0437$-$4715 presented by Choudhury et al. (2024), updates to the masses and radii of PSR J0740$+$6620 and PSR J0030$+$0451, and new $χ$EFT results for neutron star matter up to 1.5 times nuclear saturation density. Using two different high-density EOS extensions -- a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS) -- we find the radius of a 1.4$\,M_\odot$ (2.0$\,M_\odot$) neutron star to be constrained to the 95% credible ranges $12.28^{+0.50}_{-0.76}\,$km ($12.33^{+0.70}_{-1.34}\,$km) for the PP model and $12.01^{+0.56}_{-0.75}\,$km ($11.55^{+0.94}_{-1.09}\,$km) for the CS model. The maximum neutron star mass is predicted to be $2.15^{+0.14}_{-0.16}\,$$M_\odot$ and $2.08^{+0.28}_{-0.16}\,$$M_\odot$ for the PP and CS model, respectively. We explore the sensitivity of our results to different orders and different densities up to which $χ$EFT is used, and show how the astrophysical observations provide constraints for the pressure at intermediate densities. Moreover, we investigate the difference $R_{2.0} - R_{1.4}$ of the radius of 2$\,M_\odot$ and 1.4$\,M_\odot$ neutron stars within our EOS inference.
title Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Nuclear Experiment
Nuclear Theory
url https://arxiv.org/abs/2407.06790