Building a realistic neutron star from holography

Kovensky, Nicolas; Poole, Aaron; Schmitt, Andreas

doi:10.1103/physrevd.105.034022

Cited by 34 publications

(21 citation statements)

References 82 publications

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“…The reason for this contradiction turns out [46] to be the classification of nuclear matter: our setup predicts exceptionally low values of the adiabatic index γ = d log p/d log for dense nuclear matter which are below the limit value of 1.75 used in [74] so that our dense nuclear matter would be classified as quark matter in their setup. Interestingly, such low values of γ were also found recently for nuclear matter in the Witten-Sakai-Sugimoto model [28]. Apart from this small detail, we remark that our band in Fig.…”

Section: Discussionsupporting

confidence: 88%

“…It is therefore significantly increased from the bound of 230 from [46] which assumed no input from radius measurements. Interestingly, the same number, 230, was also found recently in the Witten-Sakai-Sugimoto model in [28]. Furthermore, we note that the latent heat ∆ associated with the first order transition to the quark matter phase are in excess of 740 MeV/fm 3 for all hybrid EoSs, which together with the fact that core pressures needed to support the existence of quark matter within NSs are in the unstable branch of solutions for the TOV equations, means that the hybrid EoSs do not support the existence of quark matter cores within quiescent NSs.…”

Section: Resultssupporting

confidence: 77%

“…Holographic methods have been especially useful in providing insight in the high-temperature, low-density regime of quark gluon plasma produced in heavyion collisions [23][24][25]. With the improved understanding of finite-density states in holography, the models have also recently found application in NSs [26][27][28]. Top-down models, such as the D3-D7 model [29][30][31] and the Witten-Sakai-Sugimoto model [32][33][34][35][36][37][38], which are rigorously based in string theory, are great in providing insights into the behavior of strongly coupled systems and the nature of the holographic duality.…”

Section: Introductionmentioning

confidence: 99%

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Holographic QCD in the NICER era

Jokela,

Järvinen,

Remes

2021

Preprint

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We analyze families of hybrid equations of state of cold QCD matter, which combine input from gauge/gravity duality and from various ab initio methods for nuclear matter at low density, and predict that all neutron stars are fully hadronic without quark matter cores. We focus on constraints from recent measurements by the NICER telescope on the radius and mass of the millisecond pulsar PSR J0740+6620. These results are found to be consistent with our approach: they set only mild constraints on the hybrid equations of state, and favor the most natural models which are relatively stiff at low density. Adding an upper bound on the maximal mass of neutron stars, as suggested by the analysis of the GW170817 neutron star merger event, tightens the constraints considerably. We discuss updated predictions on observables such as the transition density and latent heat of the nuclear to quark matter transition as well as the masses, radii, and tidal deformabilities of neutron stars.

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Section: Discussionsupporting

confidence: 88%

Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Holographic QCD in the NICER era

Jokela,

Järvinen,

Remes

2021

Preprint

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“…There exist arguments that suggest a universal bound c 2 s < 1/3 (see, e.g., [8,9]), thus favouring scenario i) and ii). However, a number of counter examples to this bound are known in QCD at large isospin density [10], two-color QCD [11], quarkyonic matter [12][13][14][15], models for high-density QCD [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] and models based on the gauge/gravity duality [31][32][33][34][35][36][37]. All of these example favour scenario iii).…”

mentioning

confidence: 99%

On the Sound Speed in Neutron Stars

Altiparmak¹,

Ecker²,

Rezzolla³

2022

Preprint

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Determining the sound speed cs in compact stars is an important open question with numerous implications on the behaviour of matter at large densities and hence on gravitational-wave emission from neutron stars. To this scope, we construct more than 10 7 equations of state (EOSs) with continuous sound speed and build more than 10 8 nonrotating stellar models consistent not only with nuclear theory and perturbative QCD, but also with astronomical observations. In this way, we find that EOSs with sub-conformal sound speeds, i.e., with c 2 s < 1/3 within the stars, are possible in principle but very unlikely in practice, being only 0.03% of our sample. Hence, it is natural to expect that c 2 s > 1/3 somewhere in the stellar interior. Using our large sample, we obtain estimates at 95% credibility of neutron-star radii for representative stars with 1.4 and 2.0 solar masses, R1.4 = 12.42 +0.52 −0.99 km, R2.0 = 12.12 +1.11 −1.23 km, and for the binary tidal deformability of the GW170817 event, Λ1.186 = 485 +225 −211 . Interestingly, our lower-bounds on the radii are in very good agreement with the prediction derived from very different arguments, namely, the threshold mass. Finally, we provide simple analytic expressions to determine the minimum and maximum values of Λ as a function of the chirp mass.

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“…Beyond the shaded region at least one of the constraints is violated. As a consequence, for this particular value of the 't Hooft coupling, we obtain 2.11 M M max 2.40 M and new bounds for Λ 1.4 , R 1.4 , Λ 2.1 , R 2.1 , for instance 288 Λ 1.4 580.tion and see that indeed all known astrophysical constraints can be satisfied (in contrast to the simple pointlike approximation of baryons within the same holographic model[22,30]).…”

mentioning

confidence: 52%

Predictions for neutron stars from holographic nuclear matter

Kovensky¹,

Poole²,

Schmitt³

2021

Preprint

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We discuss masses, radii, and tidal deformabilities of neutron stars constructed from the holographic Witten-Sakai-Sugimoto model. Using the same model for crust and core of the star, we combine our theoretical results with the latest astrophysical data, thus deriving more stringent constraints than given by the data alone. For instance, our calculation predicts -independent of the model parameters -an upper limit for the maximal mass of the star of about 2.46 solar masses and a lower limit of the (dimensionless) tidal deformability of a 1.4-solar-mass star of about 277.

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Building a realistic neutron star from holography

Cited by 34 publications

References 82 publications

Holographic QCD in the NICER era

Holographic QCD in the NICER era

On the Sound Speed in Neutron Stars

Predictions for neutron stars from holographic nuclear matter

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