Strangeness in astrophysics and cosmology

Boeckel, Tillmann; Hempel, Matthias; Sagert, Irina; Pagliara, Giuseppe; Sa'd, Basil A.; Schaffner-Bielich, J.

doi:10.1088/0954-3899/37/9/094005

Cited by 4 publications

(5 citation statements)

References 45 publications

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“…This gives rise to the existence of a mixed phase of quark and hadronic matter between the pure phases. A more general study of phase transitions in the presence of global and local conservation laws was discussed recently in [8]. Finite size effects in the mixed phase, such as surface tension, and Coulomb effects can lead to the appearance of structures, such as spheres, rods or planes of quark and hadronic matter, similar to what is found to happen in the hadronic liquid-gas phase transition [14,24].…”

Section: The Quark Matter Descriptionmentioning

confidence: 94%

Signals of the QCD phase transition in core collapse supernovae—microphysical input and implications on the supernova dynamics

Fischer¹,

Sagert²,

Hempel³

et al. 2010

Class. Quantum Grav.

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In contrast to heavy ion collisions, matter in astrophysical systems such as neutron stars, compact star mergers and supernova environments can be highly isospin asymmetric. We focus on core collapse supernova matter where temperatures reach tens of MeV. Both conditions, the high temperatures and isospin asymmetry, can favour an early phase transition to quark matter already close to nuclear saturation density. We examine the QCD phase transition during the early postbounce phase of core collapse supernovae. We discuss the microphysical input, i.e. the modelling of the phase transition to strange quark matter, and the consequences on the dynamical evolution as well as the observable neutrino signal from the phase transition. The equation of state for strange quark matter is based on the MIT bag model. The phase transition is constructed applying the Gibbs criterion which results in an extended coexistence region in the phase diagram between the hadronic and the quark phases, i.e. the mixed phase. The supernovae are simulated via general relativistic radiation hydrodynamics based on three-flavour Boltzmann neutrino transport in spherical symmetry. The dynamical evolution of the phase transition to quark matter is determined by an adiabatic collapse due to the softening of the equation of state in the mixed phase. The equation of state for the pure quark phase stiffens again which causes the collapse to halt and a shock wave forms at the boundary between the mixed and the pure hadronic phases. This shock accelerates and launches an explosion, which releases a burst of neutrinos dominated by electron anti-neutrinos due to the lifted degeneracy of the shock-heated hadronic material.

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Section: The Quark Matter Descriptionmentioning

confidence: 94%

Signals of the QCD phase transition in core collapse supernovae—microphysical input and implications on the supernova dynamics

Fischer¹,

Sagert²,

Hempel³

et al. 2010

Class. Quantum Grav.

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“…Correspondingly, the scale parameter grows by a factor 10 s/6 = 10 2/3 . As can be seen from equation (15), the modes which enter the horizon during this time cover an interval corresponding to a factor 10 s/3 = 10 4/3 . In Figure 11, this interval roughly lies between 10 −7 Hz and 3 • 10 −4 Hz, where the spectrum shows the expected behavior.…”

Section: F Towards a Field Theoretical Implementationmentioning

confidence: 99%

“…We will be concerned with the effect of such an inflation on the relic GW spectrum. We only mention that also structure formation is influenced, primordial magnetic fields can be produced, and new GWs can be generated through bubble collisions and turbulences, [10,15]. Thus, the scenario describes a fluid with high baryon asymmetry (see Figure 2) which is cooled down and reaches a quasi stable state still having a considerable amount of potential energy compared to the ground state.…”

Section: An Inflationary Qcd Phase Transitionmentioning

confidence: 99%

Imprints of the QCD phase transition on the spectrum of gravitational waves

2011

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We have investigated effects of the QCD phase transition on the relic GW spectrum applying several equations of state for the strongly interacting matter: Besides the bag model, which describes a first order transition, we use recent data from lattice calculations featuring a crossover. Finally, we include a short period of inflation during the transition which allows for a first order phase transition at finite baryon density. Our results show that the QCD transition imprints a step into the spectrum of GWs. Within the first two scenarios, entropy conservation leads to a step-size determined by the relativistic degrees of freedom before and after the transition. The inflation of the third scenario much stronger attenuates the high-frequency modes: An inflationary model being consistent with observation entails suppression of the spectral energy density by a factor of 10 −12 .Theories of inflation predict the existence of a background spectrum of gravitational waves (GWs) which has been created in the very early universe together with scalar perturbations of the energy density. Since then the GWs propagate freely through spacetime still retaining information about the conditions under which they originated. This is because their cross section is very small: Particles with larger cross section, such as neutrinos or photons, decouple much later and therefore carry no information about the universe at such early times and high energies. This advantage of GWs renders their direct detection impossible until today. However, observations of the binary pulsar B1913+16 (Hulse-Taylor pulsar) provide strong evidence for energy loss through emission of gravitational radiation [1].In this article we demonstrate that in spite of being decoupled, relic GWs can show imprints of subsequent cosmic events, e.g. phase transitions. We present the shape of the relic GW spectrum after different scenarios of the QCD phase transition. Before the transition, at about 200 MeV, the universe is filled with a fluid containing relativistic quarks (up, down and strange), gluons, leptons and photons. After the transition, quarks are confined into hadrons of which the pions are the only degrees of freedom which are still relativistic. From this reduction of degrees of freedom and the assumption of entropy conservation, the impact of the phase transition on the spectrum of GWs can be derived. Numerical calculations show that the shape of the spectrum after confinement and chiral symmetry breaking does not strongly depend on the order of the phase transition.However, there are scenarios for the cosmological QCD phase transition where entropy conservation is considerably violated and the gross features of the spectrum are not fixed by the estimates mentioned above. We will discuss a model which includes a short period with dominating vacuum energy density causing inflation. The melting of this energy is associated with a large entropy release. Within this model, the energy density in highfrequency GWs is much more diluted than within the scenarios ...

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“…Improvement of the model is obtained by the inclusion of corrections to first order in the QCD coupling constant in the α c < 1 (perturbative) regime (see [4] and references therein). Until now, SQM properties in dense nuclear matter and compact stars interiors have mostly been considered in the framework of the MIT Bag Model [4,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Applications of the Nambu-Jona-Lasinio [21,22] quantum field theoretical approach have also been done to describe quark matter properties in compact stars interiors [10,11,[23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

SQM studied in the Field Correlator Method

Pereira

2013

Nuclear Physics A

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By using the recent nonperturbative equation of state of the quark gluon plasma derived in the formalism of the Field Correlator Method, we investigate the bulk properties of the strange quark matter in beta-equilibrium and with charge neutrality at T=p=0. The results show that the stability of strange quark matter with respect to $^{56}Fe$ is strongly dependent on the model parameters, namely, the gluon condensate $G_2$ and the q$\bar{\rm q}$ interaction potential $V_1$. A remarkable result is that the width of the stability window decreases as $V_1$ increases, being maximum at $V_1=0$ and nearly zero at $V_1=0.5$ GeV. For $V_1$ in the range $0\leq V_1\leq0.5$ GeV, all values of $G_2$ are lower than $0.006-0.007\;{\rm GeV}^4$ obtained from comparison with lattice results at $T_c\;(\mu=0)\sim170$ MeV. These results do not favor the possibilities for the existence of (either nonnegative or negative) absolutely stable strange quark matter

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Strangeness in astrophysics and cosmology

Cited by 4 publications

References 45 publications

Signals of the QCD phase transition in core collapse supernovae—microphysical input and implications on the supernova dynamics

Signals of the QCD phase transition in core collapse supernovae—microphysical input and implications on the supernova dynamics

Imprints of the QCD phase transition on the spectrum of gravitational waves

SQM studied in the Field Correlator Method

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