Regardless of the formation mechanism, an exotic object, the double degenerate star （DDS）, is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from th...Regardless of the formation mechanism, an exotic object, the double degenerate star （DDS）, is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from the simple white dwarfs （WDs）, there is additional gravitational force provided by the unknown fermion component inside DDSs, which may strongly affect the structure and the stability of such kind of objects. Many possible and strange observational phenomena connecting with them are concisely discussed. Similar to the normal WD, this object can also experience thermonuclear explosion as type Ia supernova explosion when DDS＇s mass exceeds the maximum mass that can be supported by electron degeneracy pressure. However, since the totM mass of baryonic matter can be much lower than that of WD at Chandrasekhar mass limit, the peak luminosity should be much dimmer than what we expect before, which may throw a slight shadow on the standard candle of SN Ia in the research of cosmology.展开更多
Density waves in 3D spiral galaxies are studied.In order to eliminate the forbidden region near the corotation in the grand-design galaxies,we assume that the perturbation satisfies the stable condition Q(r)>1 over...Density waves in 3D spiral galaxies are studied.In order to eliminate the forbidden region near the corotation in the grand-design galaxies,we assume that the perturbation satisfies the stable condition Q(r)>1 over all the disk except that at the corotation.Then,a new method is put forward here to determine some basic parameters of spiral galaxies.We apply it to our Galaxy,and the results are in good agreement with the previous results.展开更多
By solving Poisson's equation for logarithmic density disturbance in three-dimensional (3D) spiral galaxies, the disturbed potential can be given on the disk. Combining it with the corresponding dispersion relatio...By solving Poisson's equation for logarithmic density disturbance in three-dimensional (3D) spiral galaxies, the disturbed potential can be given on the disk. Combining it with the corresponding dispersion relation, the local gravitational stability of our galaxy is discussed here. We have generalized the Toomre's stability criterion to the more realistic 3D galaxy models. The generalized Toomre's parameter Q near the sun is 2.08 or 2.20 for two or four armed spiral galaxy models, respectively.展开更多
Due to the intrinsic properties of neutrinos, the gravitational lens effect for a neutrino should be more colorful and meaningful than the normal lens effect of a photon. Other than the experiments operated at terrest...Due to the intrinsic properties of neutrinos, the gravitational lens effect for a neutrino should be more colorful and meaningful than the normal lens effect of a photon. Other than the experiments operated at terrestrial laboratory, in principle, we can propose a completely new astrophysical method to determine not only the nature of the gravity of lens objects but also the mixing parameters of neutrinos by analyzing neutrino trajectories near the central objects. However, the angular, energy and time resolution of the neutrino telescopes are still comparatively poor, so we just concentrate on the two classical tests of general relativity, i.e. the angular deflection and the time delay of the neutrino by a lens object as a preparative work in this paper. In addition, some simple properties of neutrino lensing are investigated.展开更多
Growing observations reveal that soft gamma-ray repeaters and anomalous x-ray pulsars are magnetars. Their magnetic fields may achieve 10^14 - 10^15G. We explore the origin of the superstrong magnetic field by conside...Growing observations reveal that soft gamma-ray repeaters and anomalous x-ray pulsars are magnetars. Their magnetic fields may achieve 10^14 - 10^15G. We explore the origin of the superstrong magnetic field by considering the magnetization of the ^3P2 superfluid neutrons inside neutron stars （NSs）. By solving the Tolman-Oppenheimer-Volkov equations together with the equation of state adopted by Elgaroy it et al. [Phys. Rev. Lett. 77 （1996） 1428] in the calculation of the neutron pairing gap, we specifically calculate the NS internal structure, the permissible region for ^3P2 superfluid neutrons inside the NS, and the total magnetic moment contributed by the orderly arranged neutron vortexes. The result shows that the induced magnetic field may cover a wide range, which is consistent with the magnetic field predicted by the standard magnetic dipole radiation for pulsar spindown.展开更多
The equation of state(EOS)of cold and dense strongly interacting matter is crucial for better research of compact stars,i.e.,neutron stars and quark stars.We generalize our improved quasi-particle model from finite te...The equation of state(EOS)of cold and dense strongly interacting matter is crucial for better research of compact stars,i.e.,neutron stars and quark stars.We generalize our improved quasi-particle model from finite temperature and zero chemical potential[Phys.Lett.B 711(2012)65]to the case of zero temperature and finite chemical potential to obtain an EOS of our improved quasi-particle model and then apply this EOS to study the structure of a quark star.The results are consistent with the most recent astronomical observational data.展开更多
This letter is emphasized on the discussion of the group velocity of disturbed galactic density waves(GDW),which is one of the two most insurmountable problems in the density waves theory.In our calculation,we find th...This letter is emphasized on the discussion of the group velocity of disturbed galactic density waves(GDW),which is one of the two most insurmountable problems in the density waves theory.In our calculation,we find that the galactic thickness has an important effect on the GDW.The dynamic time scale of GDW in our three-dimensional model can be prominently prolonged,from 36%to 60%contrasting to that of two-dimensional galactic model.However,it is still less than the lifetime of our Galaxy,which means that it is necessary to seek some other physical mechanisms to excite and sustain the GDW.展开更多
A new method is presented to determine the thickness of spiral galaxies.Based on the rigorous solution of the Poisson equation for logarithmic density disturbance in three-dimensional spiral galaxies,we have derived a...A new method is presented to determine the thickness of spiral galaxies.Based on the rigorous solution of the Poisson equation for logarithmic density disturbance in three-dimensional spiral galaxies,we have derived an accurate dispersion relation for the stellar and gaseous disk with a finite thickness.From this relation,a new method is put forward here for determining the thickness of galaxies.We apply this way to M31 and get the thickness of about 0.7kpc,which is in good agreement with the previous results.展开更多
We suggest that the fusion reaction ^16O＋^14N may be a new way to produce ^26Al in interstellar medium. Adopting different mixing modes, we investigate the impact on the production of ^26Al in explosive oxygen burnin...We suggest that the fusion reaction ^16O＋^14N may be a new way to produce ^26Al in interstellar medium. Adopting different mixing modes, we investigate the impact on the production of ^26Al in explosive oxygen burning and find that the result is extremely sensitive to mixing mechanisms. In some cases, we obtain an encouraging result, for example, the greatest final abundance of ^26Al reaches 7.779×10^-6, which means that the explosive oxygen burning may be a new origin of ^26 Al.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 10221001. LUO Xin-lian would like thank the hospitality of the Center for Gravitational Wave Astronomy at UTB, where some of the work was performed. The authors wish to thank an anonymous referee for his valuable suggestions.
文摘Regardless of the formation mechanism, an exotic object, the double degenerate star （DDS）, is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from the simple white dwarfs （WDs）, there is additional gravitational force provided by the unknown fermion component inside DDSs, which may strongly affect the structure and the stability of such kind of objects. Many possible and strange observational phenomena connecting with them are concisely discussed. Similar to the normal WD, this object can also experience thermonuclear explosion as type Ia supernova explosion when DDS＇s mass exceeds the maximum mass that can be supported by electron degeneracy pressure. However, since the totM mass of baryonic matter can be much lower than that of WD at Chandrasekhar mass limit, the peak luminosity should be much dimmer than what we expect before, which may throw a slight shadow on the standard candle of SN Ia in the research of cosmology.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19873005the Director Foundation of National Education Ministry(9528424)the National Climbing Project on Fundamental Researches.
文摘Density waves in 3D spiral galaxies are studied.In order to eliminate the forbidden region near the corotation in the grand-design galaxies,we assume that the perturbation satisfies the stable condition Q(r)>1 over all the disk except that at the corotation.Then,a new method is put forward here to determine some basic parameters of spiral galaxies.We apply it to our Galaxy,and the results are in good agreement with the previous results.
基金the National Natural Science Foundation of China under Grant No.19873005the Director Foundation of the National Education Ministry(9528424)the National Climbing Project on Fundamental Researches.
文摘By solving Poisson's equation for logarithmic density disturbance in three-dimensional (3D) spiral galaxies, the disturbed potential can be given on the disk. Combining it with the corresponding dispersion relation, the local gravitational stability of our galaxy is discussed here. We have generalized the Toomre's stability criterion to the more realistic 3D galaxy models. The generalized Toomre's parameter Q near the sun is 2.08 or 2.20 for two or four armed spiral galaxy models, respectively.
基金Supported by the National Natural Science Foundation of China under Grants No 10221001.
文摘Due to the intrinsic properties of neutrinos, the gravitational lens effect for a neutrino should be more colorful and meaningful than the normal lens effect of a photon. Other than the experiments operated at terrestrial laboratory, in principle, we can propose a completely new astrophysical method to determine not only the nature of the gravity of lens objects but also the mixing parameters of neutrinos by analyzing neutrino trajectories near the central objects. However, the angular, energy and time resolution of the neutrino telescopes are still comparatively poor, so we just concentrate on the two classical tests of general relativity, i.e. the angular deflection and the time delay of the neutrino by a lens object as a preparative work in this paper. In addition, some simple properties of neutrino lensing are investigated.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos 10775069 and 10935001, and the Research Fund for the Doctoral Program of Higher Education under Grant No 200802840009.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10173005, 10273006 and 19935030, and the Doctoral Programme of the Ministry of Education of China.
文摘Growing observations reveal that soft gamma-ray repeaters and anomalous x-ray pulsars are magnetars. Their magnetic fields may achieve 10^14 - 10^15G. We explore the origin of the superstrong magnetic field by considering the magnetization of the ^3P2 superfluid neutrons inside neutron stars （NSs）. By solving the Tolman-Oppenheimer-Volkov equations together with the equation of state adopted by Elgaroy it et al. [Phys. Rev. Lett. 77 （1996） 1428] in the calculation of the neutron pairing gap, we specifically calculate the NS internal structure, the permissible region for ^3P2 superfluid neutrons inside the NS, and the total magnetic moment contributed by the orderly arranged neutron vortexes. The result shows that the induced magnetic field may cover a wide range, which is consistent with the magnetic field predicted by the standard magnetic dipole radiation for pulsar spindown.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos 10775069,10935001,11075075the Research Fund for the Doctoral Program of Higher Education under Grant No 200802840009.
文摘The equation of state(EOS)of cold and dense strongly interacting matter is crucial for better research of compact stars,i.e.,neutron stars and quark stars.We generalize our improved quasi-particle model from finite temperature and zero chemical potential[Phys.Lett.B 711(2012)65]to the case of zero temperature and finite chemical potential to obtain an EOS of our improved quasi-particle model and then apply this EOS to study the structure of a quark star.The results are consistent with the most recent astronomical observational data.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19873005the Director Foundation of National Education Ministry(9528424)the National Climbing Project on Fundamental Researches.
文摘This letter is emphasized on the discussion of the group velocity of disturbed galactic density waves(GDW),which is one of the two most insurmountable problems in the density waves theory.In our calculation,we find that the galactic thickness has an important effect on the GDW.The dynamic time scale of GDW in our three-dimensional model can be prominently prolonged,from 36%to 60%contrasting to that of two-dimensional galactic model.However,it is still less than the lifetime of our Galaxy,which means that it is necessary to seek some other physical mechanisms to excite and sustain the GDW.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19873005the Director Foundation of National Education Ministry(9528424)the National Climbing Project on Fundamental Researches.
文摘A new method is presented to determine the thickness of spiral galaxies.Based on the rigorous solution of the Poisson equation for logarithmic density disturbance in three-dimensional spiral galaxies,we have derived an accurate dispersion relation for the stellar and gaseous disk with a finite thickness.From this relation,a new method is put forward here for determining the thickness of galaxies.We apply this way to M31 and get the thickness of about 0.7kpc,which is in good agreement with the previous results.
文摘We suggest that the fusion reaction ^16O＋^14N may be a new way to produce ^26Al in interstellar medium. Adopting different mixing modes, we investigate the impact on the production of ^26Al in explosive oxygen burning and find that the result is extremely sensitive to mixing mechanisms. In some cases, we obtain an encouraging result, for example, the greatest final abundance of ^26Al reaches 7.779×10^-6, which means that the explosive oxygen burning may be a new origin of ^26 Al.
