Critical examination of constraints on the equation of state of dense matter obtained from GW170817

Tews, Ingo; Margueron, J.; Reddy, Sanjay

doi:10.1103/physrevc.98.045804

Cited by 360 publications

(362 citation statements)

References 47 publications

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“…Similarly, including better constraints on the theoretical uncertainty at low densities by matching to chiral effective field theory with theoretical uncertainties from truncating series expansions [25][26][27][28] should further constrain our priors. We note, though, that GW170817 produces posterior processes that already tend to follow the prior relatively closely below ρ nuc (see Figure 5).…”

Section: Discussionmentioning

confidence: 99%

Nonparametric inference of neutron star composition, equation of state, and maximum mass with GW170817

2020

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The detection of GW170817 in gravitational waves provides unprecedented constraints on the equation of state (EOS) of the ultra-dense matter within the cores of neutron stars (NSs). We extend the nonparametric analysis first introduced in Landry & Essick (2019), and confirm that GW170817 favors soft EOSs. We infer macroscopic observables for a canonical 1.4 M NS, including the tidal deformability Λ1.4 = 211 +312 −137 (491 +216 −181 ) and radius R1.4 = 10.86 +2.04 −1.42 (12.51 +1.00 −0.88 ) km, as well as the maximum mass for nonrotating NSs, Mmax = 2.064 +0.260 −0.134 (2.017 +0.238 −0.087 ) M , with nonparametric priors loosely (tightly) constrained to resemble candidate EOSs from the literature. Furthermore, we find weak evidence that GW170817 involved at least one NS based on gravitational-wave data alone (B NS BBH = 3.3 ± 1.4), consistent with the observation of electromagnetic counterparts. We also investigate GW170817's implications for the maximum spin frequency of millisecond pulsars, and find that the fastest known pulsar is spinning at more than 50% of its breakup frequency at 90% confidence. We additionally find modest evidence in favor of quark matter within NSs, and GW170817 favors the presence of at least one disconnected hybrid star branch in the mass-radius relation over a single stable branch by a factor of 2. Assuming there are multiple stable branches, we find a suggestive posterior preference for a sharp softening around nuclear density followed by stiffening around twice nuclear density, consistent with a strong first-order phase transition. While the statistical evidence in favor of new physics within NS cores remains tenuous with GW170817 alone, these tantalizing hints reemphasize the promise of gravitational waves for constraining the supranuclear EOS.

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Section: Discussionmentioning

confidence: 99%

Nonparametric inference of neutron star composition, equation of state, and maximum mass with GW170817

2020

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“…The sampling of configuration space in VMC and GFMC simulations gives access to many important properties of light nuclei such as spectra, form factors, transitions, low-energy scattering, and response functions. Auxiliary Field Diffusion Monte Carlo (AFDMC) [10,98] uses Monte Carlo techniques to additionally sample the spin-isospin degrees of freedom, enabling studies of, for example, nuclei up to A = 16 [99,100] and neutron matter [90,91,101,102,103] that is so critical to determining the structure of neutron stars. QMC simulations have surely proved to be very valuable in attacking many nuclear-structure problems over the last three decades but require local chiral interactions as input.…”

Section: Chiral Effective Field Theorymentioning

confidence: 99%

“…These calculations have been successfully used to study the EOS of neutron stars, and it has been found that the resulting equations of state are consistent with astrophysical observations of pulsar masses. The EOS have also been used to study gravitational waves from neutron-star mergers [102,113,114].…”

Section: Infinite Mattermentioning

confidence: 99%

Local Nucleon-Nucleon and Three-Nucleon Interactions Within Chiral Effective Field Theory

Piarulli¹,

Tews

2020

Front. Phys.

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To obtain an understanding of the structure and reactions of nuclear systems from first principles has been a long-standing goal of nuclear physics. In this respect, few-and many-body systems provide a unique laboratory for studying nuclear interactions. During the past decades, the development of accurate representations of the nuclear force has undergone substantial progress. Particular emphasis has been devoted to chiral effective field theory (EFT), a low-energy effective representation of quantum chromodynamics (QCD). Within chiral EFT, many studies have been carried out dealing with the construction of both the nucleon-nucleon (NN ) and three-nucleon (3N ) interactions. The aim of the present article is to give a detailed overview of the chiral interaction models that are local in configuration space, and show recent results for nuclear systems obtained by employing these local chiral forces. Keywords: nuclear interactions, chiral effective field theory, local interactions, three-body forces, ab-initio calculations arXiv:2002.00032v1 [nucl-th] 31 Jan 2020 Piarulli et al. Local chiral interactionsIn fact, chiral symmetry is broken twofold. First, it is broken spontaneously, leading to the formation of Goldstone bosons, that can be identified with the pions. Second, chiral symmetry is also explicitly broken by the finite quark masses, which leads to the pion being pseudo-Goldstone bosons with finite but small mass. In contrast, isospin symmetry remains a good symmetry, because the ratio (m d − m u )/Λ QCD is very small, where m u 2.4 MeV and m d 4.8 MeV.These symmetries only allow certain operator structures for nuclear interactions. Galilean invariance, for instance, implies that nuclear interactions depend only on relative momenta between two nucleons, p = p i − p j , while symmetry under parity transformations implies that nuclear interactions cannot be Frontiers

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“…One possibility is a deconfinement phase transition from bound hadronic states to liberated quark states. The effect of a strong first-order phase transition on tidal deformabilities of the neutron star in the context of GW170817 event has been explored by a number of * jiajieli@itp.uni-frankfurt.de † sedrakian@fias.uni-frankfurt.de ‡ alford@physics.wustl.edu groups [5][6][7][8][9][10][11][12][13][14][15] showing that the hadron-quark phase transition at low enough density, ρ 2-3ρ 0 , where ρ 0 is the nuclear saturation density, relaxes the tension between the inferred tidal deformabilities and those predicted by purely hadronic models without a phase transition. Of particular interest in this context is the emergence of twin stars, where purely nucleonic and hybrid stars have the same masses, but different radii [6].…”

Section: Introductionmentioning

confidence: 99%

Relativistic hybrid stars with sequential first-order phase transitions and heavy-baryon envelopes

Sedrakian

Alford

2020

Phys. Rev. D

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We compute the mass, radius and tidal deformability of stars containing phase transitions from hadronic to quark phase(s). These quantities are computed for three types of hadronic envelopes: purely nuclear, hyperonic, and ∆-resonance-hyperon admixed matter. We consider either a single first-order phase transition to a quark phase with a maximally stiff equation of state (EoS) or two sequential first-order phase transitions mimicking a transition from hadronic (H) to a quark matter phase followed by a second phase transition to another quark phase. Such a construct emulates the results of the computations of the EoS which include 2SC and CFL color superconducting phases at low and high density. We explore the parameter space which produces low mass twin and triplet configurations where equal mass stars have substantially different radii and tidal deformabilities. We demonstrate that while for purely hadronic stiff EoS the obtained maximum mass is inconsistent with the upper limit on this quantity placed by GW170817, the inclusion of the hyperonic and ∆-resonance degrees of freedom, as well as the deconfinement phase transition at sufficiently low density, produce configuration of stars consistent with this limit. The obtained hybrid star configurations are in the mass range relevant for the interpretation of the GW170817 event. We compare our results for the tidal deformability with the limits inferred from GW170817 showing that the onset of non-nucleonic phases, such as ∆-resonance-hyperon admixed phase or/and the quark phase(s) is favored by this data if the nuclear EoS is stiff. Also, we show that low-mass twins and especially triplets proliferate the number of combinations of possible types of star that can undergo a merger event, the maximal number being six in the case of triplets. The prospects for uncovering the first-order phase transition(s) to and in quark matter via measurements of tidal deformabilities in merger events are discussed.

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Critical examination of constraints on the equation of state of dense matter obtained from GW170817

Cited by 360 publications

References 47 publications

Nonparametric inference of neutron star composition, equation of state, and maximum mass with GW170817

Nonparametric inference of neutron star composition, equation of state, and maximum mass with GW170817

Local Nucleon-Nucleon and Three-Nucleon Interactions Within Chiral Effective Field Theory

Relativistic hybrid stars with sequential first-order phase transitions and heavy-baryon envelopes

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