Výsledky vyhľadávania
Názov Viscosity of neutron star matter and r-modes in rotating pulsars Aut.údaje E. E. Kolomeitsev, D. N. Voskresensky Autor Kolomeitsev Evgeni E. 1970- (80%) UMBFP06 - Katedra fyziky
Spoluautori Voskresensky Dmitri (20%)
Zdroj.dok. Physical Review C : Nuclear Physics. Vol. 91, no. 2 (2015), pp. [1-35]. - Maryland : American Physical Society, 2015 Kľúč.slová neutrónové hviezdy neutron stars r-modes shear viscosity bulk viscosity superconductivity superfluidity Jazyk dok. angličtina Krajina Spojené štáty Systematika 539.1 Anotácia We study viscosity of the neutron star matter and $r$-mode instability in rotating neutron stars. Contributions to the shear and bulk viscosities from various processes are calculated accounting for in-medium modifications of the nucleon-nucleon interaction. A softening of the pion mode at densities larger than the nuclear saturation density $n_0$ and a possibility of the pion condensation at densities above $3/,n_0$ are included. The neutron-neutron and proton-proton pairings are incorporated, where necessary. In the shear viscosity we include the lepton contribution calculated taking into account the Landau damping in the photon exchange, the nucleon contribution described by the medium-modified one pion exchange, and some other terms, such as the novel phonon contribution in the 1S$_0$ superfluid neutron phase, and the neutrino term in the neutrino opacity region. The nucleon shear viscosity depends on the density rather moderately and proves to be much less than the lepton term. On the contrary, among the terms contributing to the bulk viscosity, induced by the delay of the relaxation of lepton concentrations in the star matter perturbed by the $r$-modes, the term from the two-nucleon medium modified Urca reactions possesses strongest density dependence (rising by several orders of magnitude for massive stars) because of the pion softening. Also, contributions to the bulk viscosity arising from other reactions induced by charged weak currents, e.g., in the Urca processes on a pion condensate and in direct Urca processes, are included. The radiative bulk viscosity induced by charged and neutral weak currents in the region of the neutrino transparency of the star is also calculated accounting for in-medium effects. We exploit the equation of state, which is similar to the Akmal-Pandharipande-Ravenhall equation of state up to $4/,n_0$, but is stiffer at higher densities, producing the maximum neutron star mass compatible with observations. The direct Urca processes do not appear up to $5/,n_0$ (corresponding to the star mass $M/simeq 1.9 M_{/odot}$). Computed with account of in-medium effects, the frequency boundary of the $r$-mode stability for the stars with the mass $/gsim 1.8 M_{/odot}$ proves to be above the frequencies of all rotating young pulsars. However, none of the conventional contributions to the viscosity are able to explain the stability of rapid rotation of old recycled pulsars in X-ray binaries. To solve this problem we propose a novel efficient mechanism associated with the appearance of condensates of low-lying modes of bosonic excitations with finite momentum and/or with an enhancement of the inhomogeneous pion/kaon condensates in some parts of the star, if the angular velocity exceeds a critical value Kategória publikačnej činnosti ADC Číslo archívnej kópie 32975 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika 
nerozpoznaný
Názov Spin excitonic and diffusive modes in superfluid Fermi liquids Aut.údaje E. E. Kolomeitsev, D. N. Voskresensky Autor Kolomeitsev Evgeni E. 1970- (50%) UMBFP06 - Katedra fyziky
Spoluautori Voskresensky Dmitri (50%)
Zdroj.dok. Physical Review C. Vol. 84, no. 6 (2011), pp. [068801-1-068801-4]. - Maryland : American Physical Society, 2011 Kľúč.slová neutron stars superconductivity Form.deskr. články - journal articles Jazyk dok. angličtina Krajina Spojené štáty Anotácia The role of the particle-particle p-wave spin interaction in Fermi liquids with an s-wave pairing is studied. Depending on the sign of the interaction, there arises either a new exciton collective mode below the pair-breaking threshold or a diffusive excitation mode above the threshold. The Landau parameters that control the interaction strength are evaluated for various systems: dilute fermion gases, a degenerate electron liquid, metals, atomic nuclei, and neutron matter. The interaction removes also the square-root singularity in the phase space of pairbreaking processes. How these effects influence the neutrino emissivity in neutron Cooper-pair recombinations in neutron stars is shown. URL Link na plný text Kategória publikačnej činnosti ADC Číslo archívnej kópie 3342 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika 
článok
Názov Weak ferromagnetism in the cuprates Súbež.n. Slabý feromagnetizmus v kuprátoch Aut.údaje Jaroslav Chovan, Nikos Papanicolaou Autor Chovan Jaroslav 1972- (50%) UMBFP06 - Katedra fyziky
Spoluautori Papanicolaou Nikos (50%)
Akcia Symposium on Wave Propagation and Electronic Structure in Disordered Systems held in honor of E N Economous 60th Birthday . sympózium , Iraklio , 15.-17.06.2000 Zdroj.dok. Physica B : condensed matter. Vol. 296, no. 1-3 (2001), pp. 163-166. - Amsterdam : Elsevier B.V., 2001 Kľúč.slová kupráty slabý feromagnetizmus supravodivosť cuprates weak ferromagnetism superconductivity Jazyk dok. angličtina Krajina Holandsko Systematika 53 Kategória publikačnej činnosti ADC Číslo archívnej kópie 26256 Katal.org. BB301 - Univerzitná knižnica Univerzity Mateja Bela v Banskej Bystrici Báza dát xpca - PUBLIKAČNÁ ČINNOSŤ Odkazy PERIODIKÁ-Súborný záznam periodika článok