Igor Iosilevskiy

Noncongruence of the nuclear liquid-gas and deconfinement phase transitions

We investigate non-congruent first-order phase transitions (PTs) relevant for heavy-ion collisions and neutron stars in Coulomb-less models. Two different phase transitions are considered: the nuclear liquid-gas PT at sub-saturation densities and the deconfinement PT at high densities and/or temperatures. For the first PT, we use the FSUgold relativistic mean-field model and for the second one the relativistic chiral SU(3) model. The chiral SU(3) model is one of the few models for the deconfinement phase transition, which contains quarks and hadrons in arbitrary proportions (i.e. a “solution”) and gives a continuous transition from pure hadronic to pure quark matter above a critical point. The study shows the universality of the applied concept of non-congruence for the two phase transitions with an upper critical point, and illustrates the different typical scales involved. In addition, we find a principle difference between the liquid-gas and the deconfinement PTs: in contrast to the ordinary Van-der-Waals-like PT, the phase coexistence line of the deconfinement PT has a negative slope in the pressure-temperature plane. Furthermore, we also find that the noncongruent features of the deconfinement PT become vanishingly small around the critical point.

Hydrogen and deuterium in shock wave experiments, ab initio simulations and chemical picture modeling

We present equation of state data of shock compressed hydrogen and deuterium. These have been calculated in the physical picture by using ab initio molecular dynamics simulations based on finite temperature density functional theory as well as in the chemical picture via the Saha-D model. The results are compared in detail with data of shock wave experiments obtained for condensed and gaseous precompressed hydrogen and deuterium targets in a wide range of shock compressions from low pressures up to megabars.

Thermodynamic Properties of Gaseous Plasmas in the Zero‐Temperature Limit

Limiting structure of thermodynamic functions of gaseous plasmas is under consideration in the limit of zero temperature and density. Remarkable tendency, which was claimed previously (Iosilevskiy and Gryaznov, 1985) is carried to extreme. Both equations of state, thermal and caloric ones obtain in this limit identical stepped structure (ionization stairs) for plasma of any single element when this limit (T -> 0, n -> 0) is carried out at fixed value of chemical potential for electrons (or atoms). The same stepped structure is valid for plasma of mixtures or compounds. This structure appears within a fixed (negative) range of chemical potential of electrons bounded below by value of major ionization potential of element and above by the value depending on sublimation energy of substance. Binding energies of all possible bound complexes (atomic, molecular, ionic and clusters) in its ground state are the only quantities that manifest itself in meaningful details of this limiting picture as location and value of every step. The sublimation energy this collection (intrinsic energy scale). All thermodynamic differential parameters (heat capacity, compressibility, etc.) obtain their remarkable betta-like structures in the zero-temperature limit (thermodynamic spectrum). All lines of these spectrum are centralized just at the elements of the intrinsic energy scale. The limiting EOS stepped structure of gaseous zero-Kelvin isotherm is generic prototype of well-known shell oscillations in EOS of gaseous plasmas at low, but finite temperature. This limiting form of plasma thermodynamics could be used as a natural basis for rigorous deduction of quasi-chemical approach (chemical picture) in frames of temperature (not density!) asymptotic expansion around this reference system.

Noncongruence of phase transitions in strongly interacting matter

First-order phase transitions (PTs) with more than one globally conserved charge, so-called noncongruent PTs, have characteristic differences compared to congruent PTs (e.g., dimensionality of phase diagrams and location of critical points and endpoints). Here we discuss the noncongruent features of the QCD PT and compare it with the nuclear liquid-gas (LG) PT, for symmetric and asymmetric matter in heavy-ion collisions and neutron stars. In addition, we have identified a principle difference between the LG and the QCD PT: they have opposite slopes in the pressure-temperature plane.

Hot third family of compact stars and the possibility of core-collapse supernova explosions

A phase transition to quark matter can lead to interesting phenomenological consequences in core-collapse supernovae, e.g., triggering an explosion in spherically symmetric models. However, until now, this explosion mechanism was only shown to be working for equations of state that are in contradiction with recent pulsar mass measurements. Here, we identify that this explosion mechanism is related to the existence of a third family of compact stars. For the equations of state investigated, the third family is only pronounced in the hot, early stages of the protocompact star and absent or negligibly small at zero temperature and thus represents a novel kind of third family. This interesting behavior is a result of unusual thermal properties induced by the phase transition, e.g., characterized by a decrease of temperature with increasing density for isentropes, and can be related to a negative slope of the phase transition line in the temperature-pressure phase diagram.

Plasma Polarization in High Gravity Astrophysical Objects

Macroscopic plasma polarization, which is created by gravitation and other mass-acting (inertial) forces in massive astrophysical objects (MAO) is under discussion. Non-ideality effect due to strong Coulomb interaction of charged particles is introduced into consideration as a new source of such polarization. Simplified situation of totally equilibrium isothermal star without relativistic effects and influence of magnetic field is considered. The study is based on variational approach combined with “local density approximation”. It leads to two local forms of thermodynamic equilibrium conditions: constancy for generalized (electro)chemical potentials and/or conditions of equilibrium for the forces acting on each charged specie. New “non-ideality potential” and “non-ideality force” appear naturally in this consideration. Hypothetical sequences of gravitational, inertial and non-ideality polarization on thermo- and hydrodynamics of MAO are under discussion (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Phase transitions in dense matter

Abstract As the density of matter increases, atomic nuclei disintegrate into nucleons and, eventually, the nucleons themselves disintegrate into quarks. The phase transitions (PTs) between these phases can vary from steep first order to smooth crossovers, depending on certain conditions. First-order PTs with more than one globally conserved charge, so-called non-congruent PTs, have characteristic differences compared to congruent PTs. In this conference proceeding we discuss the non-congruence of the quark deconfinement PT at high densities and/or temperatures relevant for heavy-ion collisions, neutron stars, proto-neutron stars, supernova explosions, and compact-star mergers.

New aspects of the QCD phase transition in proto-neutron stars and core-collapse supernovae

The QCD phase transition from hadronic to deconfined quark matter is found to be a so-called entropic phase transition, characterized, e.g., by a negative slope of the phase transition line in the pressure-temperature phase diagram. In a first part of the present proceedings it is discussed that entropic phase transitions lead to unusual thermal properties of the equation of state (EoS). For example one finds a loss of pressure (a softening) of the proto-neutron star EoS with increasing entropy. This can lead to a novel, hot third family of compact stars, which exists only in the early proto-neutron star phase. Such a hot third family can trigger explosions of core-collapse supernovae. However, so far this special explosion mechanism was found to be working only for EoSs which are not compatible with the 2 M⊙ constraint for the neutron star maximum mass. In a second part of the proceeding it is discussed which quark matter parameters could be favorable for this explosion mechanism, and have sufficiently high maximum masses at the same time.

Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

Non-congruent gas-liquid phase transition (NCPT) have been studied in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a textit{uniformly compressible} ideal electronic background /BIM(

THE SIMPLEST MODEL FOR NON-CONGRUENT FLUID{FLUID PHASE TRANSITION IN COULOMB SYSTEM

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