Signatures for quark matter from multi-messenger observations

Alford, Mark; Han, Sophia; Schwenzer, Kai

doi:10.1088/1361-6471/ab337a

Cited by 74 publications

(59 citation statements)

References 151 publications

(241 reference statements)

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“…Therefore, we investigate how this issue impacts on GW observations. The question is complementary to the existing studies of hybrid stars in the context of GW170817 (Jie Li et al 2019;Montaña et al 2019;Essick et al 2019;Alford et al 2019;Han & Steiner 2019;Bauswein et al 2019;Paschalidis et al 2018;Sieniawska et al 2019), which assume perfect-fluid systems. Natural motivations for our study are that a discontinuous quark-hadronic density profile might non-negligibly change the tidal deformability of solid/elastic hybrid stars and a nonzero shear modulus right from the bottom of the hadronic phase might be seen as a simplistic model for an elastic mixed phase.…”

Section: Introductionmentioning

confidence: 89%

“…Hybrid NSs are compact systems presenting both quark and hadronic phases. They might be possible in nature due to the existence of phase transitions in quantum chromodynamics (QCD, see Alford et al 2008;Paschalidis et al 2018;Bauswein et al 2018;Alford et al 2019). However, the order of this phase transition is unknown in the parameter range relevant for NSs (low temperatures and large chemical potentials) (Alford et al 2008).…”

Section: Introductionmentioning

confidence: 99%

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Tidal Deformations of Hybrid Stars with Sharp Phase Transitions and Elastic Crusts

Pereira

Bejger

Andersson

et al. 2020

ApJ

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Gravitational wave astronomy is expected to provide independent constraints on neutron star properties, such as their equation of state. This is possible with the measurements of binary components' tidal deformability, which alter the point-particle gravitational waveforms of neutron-star binaries. Here we provide a first study of the tidal deformability effects due to the elasticity/solidity of the crust (hadronic phase) in a hybrid neutron star, as well as the influence of a quark-hadronic phase density jump on tidal deformations. We employ the framework of nonradial perturbations with zero frequency and study hadronic phases presenting elastic aspects when perturbed (with the shear modulus approximately 1% of the pressure). We find that the relative tidal deformation change in a hybrid star with a perfect-fluid quark phase and a hadronic phase presenting an elastic part is never larger than about 2 − 4% (with respect to a perfect-fluid counterpart). These maximum changes occur when the elastic region of a hybrid star is larger than approximately 60% of the star's radius, which may happen when its quark phase is small and the density jump is large enough, or even when a hybrid star has an elastic mixed phase. For other cases, tidal deformation changes due to an elastic crust are negligible (10 −5 − 10 −1 %), therefore unlikely to be measured even with third generation detectors. Thus, only when the size of the elastic hadronic region of a hybrid star is over half of its radius, the effects of elasticity could have a noticeable impact on tidal deformations.

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Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Tidal Deformations of Hybrid Stars with Sharp Phase Transitions and Elastic Crusts

Pereira

Bejger

Andersson

et al. 2020

ApJ

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“…Understanding the nature and constrain the Equation of State (EOS) of dense neutronrich nuclear matter is a major science goal [1][2][3][4] shared by many other astrophysical observations (see, e.g., the analyses and reviews in [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]) and terrestrial nuclear experiments (see, e.g., [22][23][24][25][26][27][28][29][30][31][32][33]). However, realizing this goal is very challenging for many scientific and technical reasons.…”

Section: Introductionmentioning

confidence: 99%

Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817

Cai²,

Wang

et al. 2021

Universe

146

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The density dependence of nuclear symmetry energy is among the most uncertain parts of the Equation of State (EOS) of dense neutron-rich nuclear matter. It is currently poorly known especially at suprasaturation densities partially because of our poor knowledge about isovector nuclear interactions at short distances. Because of its broad impacts on many interesting issues, pinning down the density dependence of nuclear symmetry energy has been a longstanding and shared goal of both astrophysics and nuclear physics. New observational data of neutron stars including their masses, radii, and tidal deformations since GW170817 have helped improve our knowledge about nuclear symmetry energy, especially at high densities. Based on various model analyses of these new data by many people in the nuclear astrophysics community, while our brief review might be incomplete and biased unintentionally, we learned in particular the following: (1) The slope parameter L of nuclear symmetry energy at saturation density ρ0 of nuclear matter from 24 new analyses of neutron star observables was about L≈57.7±19 MeV at a 68% confidence level, consistent with its fiducial value from surveys of over 50 earlier analyses of both terrestrial and astrophysical data within error bars. (2) The curvature Ksym of nuclear symmetry energy at ρ0 from 16 new analyses of neutron star observables was about Ksym≈−107±88 MeV at a 68% confidence level, in very good agreement with the systematics of earlier analyses. (3) The magnitude of nuclear symmetry energy at 2ρ0, i.e., Esym(2ρ0)≈51±13 MeV at a 68% confidence level, was extracted from nine new analyses of neutron star observables, consistent with the results from earlier analyses of heavy-ion reactions and the latest predictions of the state-of-the-art nuclear many-body theories. (4) While the available data from canonical neutron stars did not provide tight constraints on nuclear symmetry energy at densities above about 2ρ0, the lower radius boundary R2.01=12.2 km from NICER’s very recent observation of PSR J0740+6620 of mass 2.08±0.07M⊙ and radius R=12.2–16.3 km at a 68% confidence level set a tight lower limit for nuclear symmetry energy at densities above 2ρ0. (5) Bayesian inferences of nuclear symmetry energy using models encapsulating a first-order hadron–quark phase transition from observables of canonical neutron stars indicated that the phase transition shifted appreciably both L and Ksym to higher values, but with larger uncertainties compared to analyses assuming no such phase transition. (6) The high-density behavior of nuclear symmetry energy significantly affected the minimum frequency necessary to rotationally support GW190814’s secondary component of mass (2.50–2.67) M⊙ as the fastest and most massive pulsar discovered so far. Overall, thanks to the hard work of many people in the astrophysics and nuclear physics community, new data of neutron star observations since the discovery of GW170817 have significantly enriched our knowledge about the symmetry energy of dense neutron-rich nuclear matter.

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“…On the opposite extreme, if the transition happens at densities lower than the central NS densities, all detected NSs are hadron-quark hybrids and the underlying EoS is degenerate with a softer hadronic EoS. In that 1 It is worth mentioning that dynamical NS properties such as NS cooling and spin-down [45][46][47], global oscillation modes [48,49], and the GW evolution of merger products [50,51] that are sensitive to transport properties would potentially provide more distinct signatures of possible phase transition in NSs [52]. However, some of these signals are more challenging to observe than BNS inspirals, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Studying strong phase transitions in neutron stars with gravitational waves

2020

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The composition of neutron stars at the extreme densities reached in their cores is currently unknown. Besides nuclear matter of normal neutrons and protons, the cores of neutron stars might harbor exotic matter such as deconfined quarks. In this paper we study strong hadron-quark phase transitions in the context of gravitational wave observations of inspiraling neutron stars. We consider upcoming detections of neutron star coalescences and model the neutron star equations of state with phase transitions through the Constant-Speed-of-Sound parametrization. We use the fact that neutron star binaries with one or more hadron-quark hybrid stars can exhibit qualitatively different tidal properties than binaries with hadronic stars of the same mass, and hierarchically model the masses and tidal properties of simulated populations of binary neutron star inspiral signals. We explore the parameter space of phase transitions and discuss under which conditions future observations of binary neutron star inspirals can identify this effect and constrain its properties, in particular the threshold density at which the transition happens and the strength of the transition. We find that if the detected population of binary neutron stars contains both hadronic and hybrid stars, the onset mass and strength of a sufficiently strong phase transition can be constrained with 50-100 detections. If the detected neutron stars are exclusively hadronic or hybrid, then it is possible to place lower or upper limits on the transition density and strength.

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Signatures for quark matter from multi-messenger observations

Cited by 74 publications

References 151 publications

Tidal Deformations of Hybrid Stars with Sharp Phase Transitions and Elastic Crusts

Tidal Deformations of Hybrid Stars with Sharp Phase Transitions and Elastic Crusts

Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817

Studying strong phase transitions in neutron stars with gravitational waves

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