With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic...With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic mean field theory （RMFT） including σ＊ and φ mesons, in comparison with the results calculated with the strong YY interaction and with no （σ＊ ,φ ） mesons included. In neutron star matter, the weak YY interaction supplies the additional repulsive interaction between hyperons while the strong YY interaction supplies the attractive one. With the weak YY interaction, the effective masses of hyperons are larger than those with the strong YY interaction while smaller than those with no （σ＊ ,φ） mesons included. The threshold star masses for the DURCA processes involving nucleons and A are not sensitive to the strength of the YY interaction. The weak YY interaction leads to larger threshold masses for the DURCA process involving [1]1 and [1]0 than the other two cases. The process involving [1]0 can take place in the neutron star only when the weak YY interaction is used. The weak YY interaction is able to bring in the agreement with the observation of the neutron star with larger mass and faster cooling than the strong YY interaction.展开更多
In the framework of the relativistic mean field theory （RMFT）, the relativistic energy losses of the direct Urea processes with hyperons （Y-DURCA ） for reactions A → p ＋ e ＋ υe and ≡^-→ A＋e＋υe are studied...In the framework of the relativistic mean field theory （RMFT）, the relativistic energy losses of the direct Urea processes with hyperons （Y-DURCA ） for reactions A → p ＋ e ＋ υe and ≡^-→ A＋e＋υe are studied in neutron stars. We calculate the energy gap of A hyperons and investigate the effects of the ^1S0 superfluidity （SF） of A hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data △ BAA ～ 1.01 ±0.20-0.11^＋0.18 MeV. The results indicate that the ^1S0 SF of A hyperons exists in most density ranges of happening the two reactions. The theoretical cooling curves are in agreement with observation data.展开更多
The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor...The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.展开更多
We have recently shown that, as a compact star containing mixed-phase matter slows down, the compression can cause deconfinement phase transition, and thus enhance the chemical deviations and raise the chemical heatin...We have recently shown that, as a compact star containing mixed-phase matter slows down, the compression can cause deconfinement phase transition, and thus enhance the chemical deviations and raise the chemical heating eiYiciency. In a previous study, only the direct Urca processes in nucleon and quark matter were considered. In this work, we extend the previous analysis to the case where the much slower modified Urca processes operate in nucleon matter. We find a fast promotion in the surface effective temperature of hybrid stars, and that the cooling process is dominated by both the nucleon and quark channels.展开更多
This study investigates the relativistic neutrino emissivity of the nucleonic and hyperonic direct Urca processes in the degenerate baryon matter of neutron stars, within the framework of relativistic mean field theor...This study investigates the relativistic neutrino emissivity of the nucleonic and hyperonic direct Urca processes in the degenerate baryon matter of neutron stars, within the framework of relativistic mean field theory. In particular, we study the influence of the isovector scalar interaction on the nucleonic and hyperonic direct Urca processes by exchanging δ mesons. The results indicate that δ mesons lead to obvious enhancement of the total neutrino emissivity, which must result in a more rapid cooling rate of neutron star matter.展开更多
In the framework of the relativistic mean field theory, the effects of the δ meson on the direct Urca （DURCA） processes are investigated. In a neutron star, the DURCA processes involving nucleons, A and - can ta...In the framework of the relativistic mean field theory, the effects of the δ meson on the direct Urca （DURCA） processes are investigated. In a neutron star, the DURCA processes involving nucleons, A and - can take place while the process involving the 0 can not. With the inclusion of the δ meson, the threshold densities for the DURCA processes become lower. With the δ included, the threshold neutron star mass for the DURCA process among nucleons and electrons becomes smaller while the threshold masses for the processes involving hyperons become larger. When the δ meson is included, the total neutrino emissivity remarkably increases in the density range of 0.32-0.41 fm-3. The total neutrino luminosity increases with the neutron star mass first and then decreases. The neutrino luminosity gets larger with the inclusion of the δ meson. The cooling of the EXO0748-676 is sensitive to the isovector scalar interaction.展开更多
Based on covariant density functional theory, we study the effects of rotation on the nucleon direct URCA（N-DURCA） process for traditional and hyperonic neutron stars. The calculated results indicate that, for a fix...Based on covariant density functional theory, we study the effects of rotation on the nucleon direct URCA（N-DURCA） process for traditional and hyperonic neutron stars. The calculated results indicate that, for a fixed mass sequence of rotational traditional neutron stars, the neutrino emissivity of the star is nearly invariant with increasing frequency, while it always increases for rotational hyperonic neutron stars. Thus, rotation has different effects on the N-DURCA process for these two kinds of neutron stars.展开更多
In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The ca...In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.展开更多
The Uranium exploration history of the Central African Republic(CAR)extends on two periods separated by the independence in 1960,of the ex-Ubangi-Chari,a colony of French Equatorial Africa.The uranium research is cont...The Uranium exploration history of the Central African Republic(CAR)extends on two periods separated by the independence in 1960,of the ex-Ubangi-Chari,a colony of French Equatorial Africa.The uranium research is contemporary of the French Atomic Energy Commission(CEA)implementation in this country in 1947 and done by the CEA.There began the first period.The second period started after the 1960 year.Before the independence,the exploration works were realized in two stages from 1947 to 1957 and from 1958 to 1961.The first stage regarded the recognizing of uranium occurrences in the magmatic and pegmatitic formations.For this,three missions were organized in the east of the CAR.The first mission took place from March to July 1947.The second mission was realized from April to June 1949,and the third mission from November to April 1956.The second stage had concerned the uranium research in sedimentary basins by the prospecting Mba?ki Series(January 1958-January 1960)and Fouroumbala Series(August 1959-June 1961).These series offered the chance to CEA to discover the Bakouma uranium deposits.After this discovery in 1965,the falls of prices of the uranium provoked altered stoppings and resumptions of works with the following societies:the Company of uranium ores of Bakouma(URBA)1969;Centralafrican uranium(URCA)in 1975 but dissolved in 1981;in 1989-1991,the Japanese Nuclear Power Corporation(PNC)for a deposit re-examination;URAMIN Centrafrique in 2004-2005 and AREVA Resources Centrafrique in 2007.The last-mentioned had stopped works since 2012.展开更多
基金Supported by the Natural Science Fundamental Research Project of Jiangsu Colleges and Universities under Grant No.10KJB140002
文摘With a weak hyperon-hyperon （YY） interaction deduced from the new experimental data of AA potential, this paper has performed a calculation of the direct Urca （DURCA） processes in the framework of the relativistic mean field theory （RMFT） including σ＊ and φ mesons, in comparison with the results calculated with the strong YY interaction and with no （σ＊ ,φ ） mesons included. In neutron star matter, the weak YY interaction supplies the additional repulsive interaction between hyperons while the strong YY interaction supplies the attractive one. With the weak YY interaction, the effective masses of hyperons are larger than those with the strong YY interaction while smaller than those with no （σ＊ ,φ） mesons included. The threshold star masses for the DURCA processes involving nucleons and A are not sensitive to the strength of the YY interaction. The weak YY interaction leads to larger threshold masses for the DURCA process involving [1]1 and [1]0 than the other two cases. The process involving [1]0 can take place in the neutron star only when the weak YY interaction is used. The weak YY interaction is able to bring in the agreement with the observation of the neutron star with larger mass and faster cooling than the strong YY interaction.
基金Supported by National Natural Science Foundation of China under Grant Nos. 10675024, 11075063the National Fundamental Fund project Subsidy Funds of Personnel Training J0730311
文摘In the framework of the relativistic mean field theory （RMFT）, the relativistic energy losses of the direct Urea processes with hyperons （Y-DURCA ） for reactions A → p ＋ e ＋ υe and ≡^-→ A＋e＋υe are studied in neutron stars. We calculate the energy gap of A hyperons and investigate the effects of the ^1S0 superfluidity （SF） of A hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data △ BAA ～ 1.01 ±0.20-0.11^＋0.18 MeV. The results indicate that the ^1S0 SF of A hyperons exists in most density ranges of happening the two reactions. The theoretical cooling curves are in agreement with observation data.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11447165,11373047 and 11265009the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2016056
文摘The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.
基金Supported by National Natural Science Foundation of China (1179008, 11003005)
文摘We have recently shown that, as a compact star containing mixed-phase matter slows down, the compression can cause deconfinement phase transition, and thus enhance the chemical deviations and raise the chemical heating eiYiciency. In a previous study, only the direct Urca processes in nucleon and quark matter were considered. In this work, we extend the previous analysis to the case where the much slower modified Urca processes operate in nucleon matter. We find a fast promotion in the surface effective temperature of hybrid stars, and that the cooling process is dominated by both the nucleon and quark channels.
基金Supported by Natural Science Foundation of China(11447165,11373047,11303063)
文摘This study investigates the relativistic neutrino emissivity of the nucleonic and hyperonic direct Urca processes in the degenerate baryon matter of neutron stars, within the framework of relativistic mean field theory. In particular, we study the influence of the isovector scalar interaction on the nucleonic and hyperonic direct Urca processes by exchanging δ mesons. The results indicate that δ mesons lead to obvious enhancement of the total neutrino emissivity, which must result in a more rapid cooling rate of neutron star matter.
基金Supported by National Natural Science Foundation of China (10675024,11075063)Natural Science Fundamental Research Project of Jiangsu Colleges and Universities (10KJB140002)
文摘In the framework of the relativistic mean field theory, the effects of the δ meson on the direct Urca （DURCA） processes are investigated. In a neutron star, the DURCA processes involving nucleons, A and - can take place while the process involving the 0 can not. With the inclusion of the δ meson, the threshold densities for the DURCA processes become lower. With the δ included, the threshold neutron star mass for the DURCA process among nucleons and electrons becomes smaller while the threshold masses for the processes involving hyperons become larger. When the δ meson is included, the total neutrino emissivity remarkably increases in the density range of 0.32-0.41 fm-3. The total neutrino luminosity increases with the neutron star mass first and then decreases. The neutrino luminosity gets larger with the inclusion of the δ meson. The cooling of the EXO0748-676 is sensitive to the isovector scalar interaction.
基金Supported by National Natural Science Foundation of China(11545011,11405096)the Shandong Natural Science Foundation(ZR2014AQ012)+1 种基金the Young Scholars Program of Shandong University,Weihai(2015WHWLJH01)the Fundamental Research Funds for the Central Universities(lzujbky-2016-30)
文摘Based on covariant density functional theory, we study the effects of rotation on the nucleon direct URCA（N-DURCA） process for traditional and hyperonic neutron stars. The calculated results indicate that, for a fixed mass sequence of rotational traditional neutron stars, the neutrino emissivity of the star is nearly invariant with increasing frequency, while it always increases for rotational hyperonic neutron stars. Thus, rotation has different effects on the N-DURCA process for these two kinds of neutron stars.
基金supported by National Natural Science Foundation of China (Nos.10675024,11075063)National Fundamental Fund Project of Subsidy Funds of Personnel Training of China (J0730311)
文摘In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.
文摘The Uranium exploration history of the Central African Republic(CAR)extends on two periods separated by the independence in 1960,of the ex-Ubangi-Chari,a colony of French Equatorial Africa.The uranium research is contemporary of the French Atomic Energy Commission(CEA)implementation in this country in 1947 and done by the CEA.There began the first period.The second period started after the 1960 year.Before the independence,the exploration works were realized in two stages from 1947 to 1957 and from 1958 to 1961.The first stage regarded the recognizing of uranium occurrences in the magmatic and pegmatitic formations.For this,three missions were organized in the east of the CAR.The first mission took place from March to July 1947.The second mission was realized from April to June 1949,and the third mission from November to April 1956.The second stage had concerned the uranium research in sedimentary basins by the prospecting Mba?ki Series(January 1958-January 1960)and Fouroumbala Series(August 1959-June 1961).These series offered the chance to CEA to discover the Bakouma uranium deposits.After this discovery in 1965,the falls of prices of the uranium provoked altered stoppings and resumptions of works with the following societies:the Company of uranium ores of Bakouma(URBA)1969;Centralafrican uranium(URCA)in 1975 but dissolved in 1981;in 1989-1991,the Japanese Nuclear Power Corporation(PNC)for a deposit re-examination;URAMIN Centrafrique in 2004-2005 and AREVA Resources Centrafrique in 2007.The last-mentioned had stopped works since 2012.
