The Equation of State of Neutron-Rich Matter at Fourth Order of Chiral Effective Field Theory and the Radius of a Medium-Mass Neutron Star

Sammarruca, Francesca; Millerson, Randy

doi:10.3390/universe8020133

Title: The Equation of State of Neutron-Rich Matter at Fourth Order of Chiral Effective Field Theory and the Radius of a Medium-Mass Neutron Star

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Abstract

We report neutron star predictions based on our most recent equations of state. These are derived from chiral effective field theory, which allows for a systematic development of nuclear forces, order by order. We utilize high-quality two-nucleon interactions and include all three-nucleon forces up to fourth order in the chiral expansion. Our ab initio predictions are restricted to the domain of applicability of chiral effective field theory. However, stellar matter in the interior of neutron stars can be up to several times denser than normal nuclear matter at saturation, and its composition is essentially unknown. Following established practices, we extend our microscopic predictions to higher densities matching piecewise polytropes. The radius of the average-size neutron star, about 1.4 solar masses, is sensitive to the pressure at normal densities, and thus it is suitable to constrain ab initio theories of the equation of state. For this reason, we focus on the radius of medium-mass stars. We compare our results with other theoretical predictions and recent constraints.

Authors:: Sammarruca, Francesca; Millerson, Randy

Publication Date:: Sat Feb 19 00:00:00 EST 2022

Research Org.:: Univ. of Idaho, Moscow, ID (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1845915

Alternate Identifier(s):: OSTI ID: 1855740

Grant/Contract Number:: FG02-03ER41270

Resource Type:: Published Article

Journal Name:: Universe

Additional Journal Information:: Journal Name: Universe Journal Volume: 8 Journal Issue: 2; Journal ID: ISSN 2218-1997

Publisher:: MDPI AG

Country of Publication:: Switzerland

Language:: English

Subject:: 79 ASTRONOMY AND ASTROPHYSICS; neutron matter; equation of state; neutron star; symmetry energy; chiral effective field theory

Citation Formats


                    Sammarruca, Francesca, and Millerson, Randy. The Equation of State of Neutron-Rich Matter at Fourth Order of Chiral Effective Field Theory and the Radius of a Medium-Mass Neutron Star.  Switzerland: N. p., 2022. 
Web.  doi:10.3390/universe8020133.

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                    Sammarruca, Francesca, & Millerson, Randy. The Equation of State of Neutron-Rich Matter at Fourth Order of Chiral Effective Field Theory and the Radius of a Medium-Mass Neutron Star.  Switzerland.  https://doi.org/10.3390/universe8020133

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                    Sammarruca, Francesca, and Millerson, Randy. Sat .  
"The Equation of State of Neutron-Rich Matter at Fourth Order of Chiral Effective Field Theory and the Radius of a Medium-Mass Neutron Star".  Switzerland.  https://doi.org/10.3390/universe8020133.

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@article{osti_1845915,

  title        = {The Equation of State of Neutron-Rich Matter at Fourth Order of Chiral Effective Field Theory and the Radius of a Medium-Mass Neutron Star},

  author       = {Sammarruca, Francesca and Millerson, Randy},

  abstractNote = {We report neutron star predictions based on our most recent equations of state. These are derived from chiral effective field theory, which allows for a systematic development of nuclear forces, order by order. We utilize high-quality two-nucleon interactions and include all three-nucleon forces up to fourth order in the chiral expansion. Our ab initio predictions are restricted to the domain of applicability of chiral effective field theory. However, stellar matter in the interior of neutron stars can be up to several times denser than normal nuclear matter at saturation, and its composition is essentially unknown. Following established practices, we extend our microscopic predictions to higher densities matching piecewise polytropes. The radius of the average-size neutron star, about 1.4 solar masses, is sensitive to the pressure at normal densities, and thus it is suitable to constrain ab initio theories of the equation of state. For this reason, we focus on the radius of medium-mass stars. We compare our results with other theoretical predictions and recent constraints.},

  doi          = {10.3390/universe8020133},

  journal      = {Universe},

  number       = 2,

  volume       = 8,

  place        = {Switzerland},

  year         = {Sat Feb 19 00:00:00 EST 2022},

  month        = {Sat Feb 19 00:00:00 EST 2022}

}

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