We will introduce the construction and design of a new simultaneous three-channel multicolor CCD photometer.This photometer has been mounted on the 1.2 m telescope at Jilin Astronomical Observatory,and is applied to s...We will introduce the construction and design of a new simultaneous three-channel multicolor CCD photometer.This photometer has been mounted on the 1.2 m telescope at Jilin Astronomical Observatory,and is applied to study space debris,gamma-ray burst afterglows,asteroids and other rapidly variable objects.As one of the ground follow-up telescopes of the Chinese-French Space-based multi-band astronomical Variable Objects Monitor(SVOM)mission,it appears very essential to evaluate the performance of the photometry system of this photometer,which can achieve simultaneous imaging within a field of view of 21’.5×21’.5,21’.5×21’.5 and21’.3×21’.3 in the Sloan Digital Sky Survey(SDSS)g’,r’,i’bands,respectively.Photometric calibrations were carried out by using plenty of SDSS standard stars,and the relationship between the photometric system and the Johnson-Bessel filter system was also studied.The results of the performance evaluation from observing open cluster M67 are presented.展开更多
Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct t...Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.展开更多
The range of the U bosonic coupling constants in neutron star matter is a very interesting but still unsolved problem which has multifaceted influences in nuclear physics,particle physics,astrophysics and cosmology.Th...The range of the U bosonic coupling constants in neutron star matter is a very interesting but still unsolved problem which has multifaceted influences in nuclear physics,particle physics,astrophysics and cosmology.The combination of the theoretical numerical simulation and the recent observations provides a very good opportunity to solve this problem.In the present work,the range of the U bosonic coupling constants is inferred based on the three relations of the mass–radius,mass-frequency and mass-tidal deformability in neutron stars containing hyperons using the GM1,TM1 and NL3 parameter sets under the two flavor symmetries of SU(6)and SU(3)in the framework of the relativistic mean field theory.Combined with observations from PSRs J1614-2230,J0348+0432,J2215-5135,J0952-0607,J0740+6620,J0030-0451,J1748-2446ad,XTE J1739-285,GW170817 and GW190814 events,our numerical results show that the U bosonic coupling constants may tend to be within the range from 0 to 20 GeV^(-2)in neutron star containing hyperons.Moreover,the numerical results of the three relations obtained by the SU(3)symmetry are better in accordance with observation data than those obtained by the SU(6)symmetry.The results will help us to improve the strict constraints of the equation of state for neutron stars containing hyperons.展开更多
Ground-based optical observation has unique advantages in space target observation.However,due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes,the space debris in the image ...Ground-based optical observation has unique advantages in space target observation.However,due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes,the space debris in the image is weak and easily drowned in noise.In order to solve the above problems,we use digital image processing technology to extract faint space debris.We propose a high detection rate space debris automatic extraction algorithm,aiming to automatically detect space debris.We first establish a new space target description model.Our algorithm is mainly divided into two stages.The purpose of the first stage is to reduce the influence of a large number of stars.We perform wavelet transform and guided filtering for three consecutive frames,and the reconstructed wavelet that takes the median value can achieve the effect of eliminating stars.In the second stage,we adopt the method of robust principal component analysis and attribute the problem of target detection to the problem of separating the target and background of a single frame of image.After a large number of experimental results analysis,it is proved that the algorithm can effectively detect faint debris in the monitoring system of small aperture telescope,and has high precision and low computational complexity.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
The nucleonic ~1S_0 superfluidity is investigated by solving the gap equation for the Reid soft-core potential as the nucleon-nucleon interaction in neutron star(NS) matter which is considered to be made up of p, e, ...The nucleonic ~1S_0 superfluidity is investigated by solving the gap equation for the Reid soft-core potential as the nucleon-nucleon interaction in neutron star(NS) matter which is considered to be made up of p, e, μ and condensed antikaon matter. We mainly study the influence of the soft pion-induced potential on the nucleonic^1S_0 pairing gaps in the above NS matter. It is found that the intensities of the nucleonic ~1S_0 pairing gaps including the soft pion-induced potential are smaller than those calculated in the case of not including the soft pion-induced potential. Furthermore, the nucleonic ~1S_0 pairing gaps with the soft pion-induced potential fall into decline with the deepening of the optical potential of antikaons in the above NS matter, whereas they increase with the parameter η for the fixed optical potential of antikaons. Due to the appearance of the soft pion-induced potential, the maximum values of nucleonic ~1S_0 pairing gaps at parameter η = 0.20,0.55 are suppressed by1.7%-6.8% with respect to the case without soft pion-induced potential in the above NS matter.展开更多
In this work, we experimentally demonstrate an image information transfer between two channels by using slow light based on electromagnetically induced transparency（EIT） in a solid. The probe optical image is slowed...In this work, we experimentally demonstrate an image information transfer between two channels by using slow light based on electromagnetically induced transparency（EIT） in a solid. The probe optical image is slowed due to steep dispersion induced by EIT. By applying an additional control field to an EIT-driven medium, the slowed image is transferred into two information channels. Image intensities between two information channels can be controlled by adjusting the intensities of the control fields. The similarity of output images is further analyzed. This image information transfer allows for manipulating images in a controlled fashion, and will be important in further information processing.展开更多
A neatly controllable photonic band gap formed in a four-level tripod system in the solid material,Pr^(3+)-doped yttrium orthosilicate(Pr:YSO)is investigated.Driven by two standing waves,the sample is just like a phot...A neatly controllable photonic band gap formed in a four-level tripod system in the solid material,Pr^(3+)-doped yttrium orthosilicate(Pr:YSO)is investigated.Driven by two standing waves,the sample is just like a photonic crystal to the weak probe.Based on the numerical simulation and the analytic result we present a clear and full-scale view on the induced band gap in the inhomogeneously broadened tripod system.展开更多
The ^1 S0 nucleonic superfluids are investigated within the relativistic meanfield model and Bardeen-Cooper-Schrieffer theory in hyperonic neutron stars. The ^1 S0 pairing gaps of neutrons and protons are calculated b...The ^1 S0 nucleonic superfluids are investigated within the relativistic meanfield model and Bardeen-Cooper-Schrieffer theory in hyperonic neutron stars. The ^1 S0 pairing gaps of neutrons and protons are calculated based on the Reid soft-core interaction as the nucleon-nucleon interaction. In particular, we have studied the influence of degrees of freedom for hyperons on the ^1 S0 nucleonic pairing gap in neutron star matter. It is found that the appearance of hyperons has little impact on the baryonic density range and the size of the ^1S0 neutronic pairing gap; the ^1S0 protonic pairing gap also decreases slightly in this region where ρB = 0.0-0.393 fm^-3. However, if baryonic density becomes greater than 0.393 fm^-3, the ^1S0 protonic pairing gap obviously increases. In addition, the possible range for a protonic superfluid is obviously enlarged due to the presence of hyperons. In our results, the hyperons change the 1 So protonic pairing gap, which must change the cooling properties of neutron stars.展开更多
The GW170817 binary neutron star merger event in 2017 has raised great interest in the theoretical research f neutron stars. The structure and cooling properties of dark-matter-admixed neutron stars are studied here u...The GW170817 binary neutron star merger event in 2017 has raised great interest in the theoretical research f neutron stars. The structure and cooling properties of dark-matter-admixed neutron stars are studied here using relativistic mean field theory and cooling theories. The non-self-annihilating dark matter(DM) component is assumed to be ideal fermions, among which the weak interaction is considered. The results show that pulsars J1614-2230, J0348+0432 and EXO 0748-676 may all contain DM with the particle mass of 0.2–0.4 GeV. However,it is found that the effect of DM on neutron star cooling is complicated. Light DM particles favor the fast cooling of neutron stars, and the case is converse for middle massive DM. However, high massive DM particles, around1.0 GeV, make the low mass(around solar mass) neutron star still undergo direct Urca process of nucleons at the core, which leads the DM-admixed stars cool much more quickly than the normal neutron star, and cannot support the direct Urca process with a mass lower than 1.1 times solar mass. Thus, we may conjecture that if small(around solar mass) and super cold(at least surface temperature 5–10 times lower than that of the usual observed data) pulsars are observed, then the star may contain fermionic DM with weak self-interaction.展开更多
In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degre...In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.展开更多
Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calc...Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a (∧∧) pair. The parameter set we use is in line with the recent experimental data △B_(∧∧) ~ 1.01 ± 0.20_+0.18-0.11 MeV.It is found that with σ^(*) and φ mesons the pairing energy gap △F of ∧ hyperons and the corresponding SF critical temperature T_(C∧) are suppressed.In addition the NS mass range of ∧ hyperon SF is enlarged obviously.展开更多
We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interact...We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.展开更多
We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model f...We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model for CFL quark matter.In our calculation results,we find that with the increase of the CFL energy gap there exists a transition behavior,which goes from the hadron star range through the transition range into the CFL quark star range.The observation data of PRS J1614-2230 are in the hadron star range(withΔ<40MeV).We also find that with hyperons the equation of state(EOS)for the hybrid star matter with the CFL quark matter core has a small change,which can be disregarded.展开更多
This note introduces the performance and observation summary of the SLR system at Changcun Observatory, the Chinese Academy of Sciences. The performance of the SLR system has been greatly improved since August 1997. T...This note introduces the performance and observation summary of the SLR system at Changcun Observatory, the Chinese Academy of Sciences. The performance of the SLR system has been greatly improved since August 1997. The single shot precision is improved from 5-7 cm to 1-2 cm and the normal point precision reaches 4-7 mm. The long-term stability is better than 1 cm. The amount of observation has been increased from 1000 to over 3000 passes. The whole performance of Changcun SLR system has reached the advanced level among the worldwide SLR stations.展开更多
Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the s...Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the surface gravitational redshift and the Keplerian frequency for the traditional neutron star and the hyperon star matter within the relativistic mean field theory,using the GM1 and TM1 parameter sets by considering the two flavor symmetries of SU(6)and SU(3)combined with the observations of PSR J1614-2230,PSR J0348+0432,PSR J0030+0451,RX J0720.4-3125,and 1E 1207.4-5209.It is found that the existence of dark energy leads to the softened equations of the state of the traditional neutron star and the hyperon star.The radius of a fixed-mass traditional neutron star(or hyperon star)with dark energy becomes smaller,which leads to increased compactness.The existence of dark energy can also enhance the surface gravitational redshift and the Keplerian frequency of traditional neutron stars and hyperon stars.The growth of the Keplerian frequency may cause the spin rate to speed up,which may provide a possible way to understand and explain the pulsar glitch phenomenon.Specifically,we infer that the mass and the surface gravitational redshift of PSR J1748-2446ad without dark energy for the GM1(TM1)parameter set are 1.141 M_(☉)(1.309 M_(☉))and 0.095(0.105),respectively.The corresponding values for the GM1(TM1)parameter set are 0.901 M_(☉)(1.072M_(☉))and 0.079(0.091)if PSR J1748-2446ad contains dark energy withα=0.05.PSR J1748-2446ad may be a low-mass pulsar with a lower surface gravitational redshift under our selected models.展开更多
Observatories typically deploy all-sky cameras for monitoring cloud cover and weather conditions.However,many of these cameras lack scientific-grade sensors,r.esulting in limited photometric precision,which makes calc...Observatories typically deploy all-sky cameras for monitoring cloud cover and weather conditions.However,many of these cameras lack scientific-grade sensors,r.esulting in limited photometric precision,which makes calculating the sky area visibility distribution via extinction measurement challenging.To address this issue,we propose the Photometry-Free Sky Area Visibility Estimation(PFSAVE)method.This method uses the standard magnitude of the faintest star observed within a given sky area to estimate visibility.By employing a pertransformation refitting optimization strategy,we achieve a high-precision coordinate transformation model with an accuracy of 0.42 pixels.Using the results of HEALPix segmentation is also introduced to achieve high spatial resolution.Comprehensive analysis based on real allsky images demonstrates that our method exhibits higher accuracy than the extinction-based method.Our method supports both manual and robotic dynamic scheduling,especially under partially cloudy conditions.展开更多
In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser （EDFL） by using gold nanostars （GNSs） as a saturable absorber （SA） for the first time, to the best of our know...In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser （EDFL） by using gold nanostars （GNSs） as a saturable absorber （SA） for the first time, to the best of our knowledge. In comparison with other gold nanomorphologies, GNSs have multiple localized surface plasmon resonances, which means that they can be used to construct wideband ultrafast pulse lasers. By inserting the GNS SA into an EDFL cavity pumped by a 980 nm laser diode, a stable passively Q-switched laser at 1564.5 nm was achieved for a threshold pump power of 40 mW. By gradually increasing the pump power from 40 to 120 mW, the pulse duration decreases from 12.8 to 5.3 its and the repetition rate increases from 10 to 17 kHz. Our results indicate that the GNSs are a promising SA for constructing pulse lasers.展开更多
We propose and demonstrate a widely tunable passively Q-switched Ho^(3+)∕Pr^(3+)-codoped ZrF_4-BaF_2-LaF_3-AlF_3-NaF fiber laser operating in the 2.8 μm mid-infrared(MIR) waveband based on a single-walled carbon nan...We propose and demonstrate a widely tunable passively Q-switched Ho^(3+)∕Pr^(3+)-codoped ZrF_4-BaF_2-LaF_3-AlF_3-NaF fiber laser operating in the 2.8 μm mid-infrared(MIR) waveband based on a single-walled carbon nanotube(SWCNT) saturable absorber(SA). The SWCNTs have diameters ranging from 1.4 to 1.7 nm. The modulation depth and saturation intensity of the SWCNT SA measured at 2850 nm are 16.5% and 1.66 MW∕cm^2, respectively. Stable Q-switched pulses with the shortest pulse duration of 1.46 μs and the maximum pulse energy of 0.43 μJ are achieved at a launched pump power of 445.6 mW. The combined use of a broadband SWCNT SA and a plane ruled grating ensures a broad continuously tuning range of 55.0 nm from 2837.6 to 2892.6 nm.The output powers, emission spectra, repetition rates, and pulse durations at different tuning wavelengths are also characterized and analyzed. Our results indicate that SWCNTs can be excellent broadband SAs in the 3 μm MIR region. To the author's knowledge, this is the first demonstration of a widely tunable carbon-nanotubeenabled passively Q-switched fiber laser operating in the 2.8 μm MIR waveband.展开更多
It is a common practice to evaluate probability density function or matter spatial density function from statistical samples. Kernel density estimation is a frequently used method, but to select an optimal bandwidth o...It is a common practice to evaluate probability density function or matter spatial density function from statistical samples. Kernel density estimation is a frequently used method, but to select an optimal bandwidth of kernel estimation, which is completely based on data samples, is a long-term issue that has not been well settled so far. There exist analytic formulae of optimal kernel bandwidth, but they cannot be applied directly to data samples,since they depend on the unknown underlying density functions from which the samples are drawn. In this work, we devise an approach to pick out the totally data-based optimal bandwidth. First, we derive correction formulae for the analytic formulae of optimal bandwidth to compute the roughness of the sample's density function. Then substitute the correction formulae into the analytic formulae for optimal bandwidth, and through iteration we obtain the sample's optimal bandwidth. Compared with analytic formulae, our approach gives very good results, with relative differences from the analytic formulae being only 2%～3% for sample size larger than 10~4. This approach can also be generalized easily to cases of variable kernel estimations.展开更多
基金Supported by the National Natural Science Foundation of China。
文摘We will introduce the construction and design of a new simultaneous three-channel multicolor CCD photometer.This photometer has been mounted on the 1.2 m telescope at Jilin Astronomical Observatory,and is applied to study space debris,gamma-ray burst afterglows,asteroids and other rapidly variable objects.As one of the ground follow-up telescopes of the Chinese-French Space-based multi-band astronomical Variable Objects Monitor(SVOM)mission,it appears very essential to evaluate the performance of the photometry system of this photometer,which can achieve simultaneous imaging within a field of view of 21’.5×21’.5,21’.5×21’.5 and21’.3×21’.3 in the Sloan Digital Sky Survey(SDSS)g’,r’,i’bands,respectively.Photometric calibrations were carried out by using plenty of SDSS standard stars,and the relationship between the photometric system and the Johnson-Bessel filter system was also studied.The results of the performance evaluation from observing open cluster M67 are presented.
基金supported by the National Key Research and Development Program of China(2021YFA0715101)partly supported by a National LLR station project+2 种基金the National Natural Science Foundation of China(NSFC,Grant Nos.11973064 and 42101413)Jilin Province Mid-youth science and technology innovation and entrepreneurship outstanding talent project(20220508147RC)the Changchun City and Chinese Academy of Sciences Science and Technology Cooperation High-tech Industrialization Special Fund Project(21SH05)。
文摘Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.
文摘The range of the U bosonic coupling constants in neutron star matter is a very interesting but still unsolved problem which has multifaceted influences in nuclear physics,particle physics,astrophysics and cosmology.The combination of the theoretical numerical simulation and the recent observations provides a very good opportunity to solve this problem.In the present work,the range of the U bosonic coupling constants is inferred based on the three relations of the mass–radius,mass-frequency and mass-tidal deformability in neutron stars containing hyperons using the GM1,TM1 and NL3 parameter sets under the two flavor symmetries of SU(6)and SU(3)in the framework of the relativistic mean field theory.Combined with observations from PSRs J1614-2230,J0348+0432,J2215-5135,J0952-0607,J0740+6620,J0030-0451,J1748-2446ad,XTE J1739-285,GW170817 and GW190814 events,our numerical results show that the U bosonic coupling constants may tend to be within the range from 0 to 20 GeV^(-2)in neutron star containing hyperons.Moreover,the numerical results of the three relations obtained by the SU(3)symmetry are better in accordance with observation data than those obtained by the SU(6)symmetry.The results will help us to improve the strict constraints of the equation of state for neutron stars containing hyperons.
基金supported in part by the National Natural Science Foundation of China(NSFC)(U2031129 and 12003052)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2018079)。
文摘Ground-based optical observation has unique advantages in space target observation.However,due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes,the space debris in the image is weak and easily drowned in noise.In order to solve the above problems,we use digital image processing technology to extract faint space debris.We propose a high detection rate space debris automatic extraction algorithm,aiming to automatically detect space debris.We first establish a new space target description model.Our algorithm is mainly divided into two stages.The purpose of the first stage is to reduce the influence of a large number of stars.We perform wavelet transform and guided filtering for three consecutive frames,and the reconstructed wavelet that takes the median value can achieve the effect of eliminating stars.In the second stage,we adopt the method of robust principal component analysis and attribute the problem of target detection to the problem of separating the target and background of a single frame of image.After a large number of experimental results analysis,it is proved that the algorithm can effectively detect faint debris in the monitoring system of small aperture telescope,and has high precision and low computational complexity.
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 the Open Foundation of Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processingthe Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2016056+1 种基金the Development Project of Science and Technology of Jilin Province under Grant No 20180520077JHthe National Natural Science Foundation of China under Grant Nos 11805022 and 11803057
文摘The nucleonic ~1S_0 superfluidity is investigated by solving the gap equation for the Reid soft-core potential as the nucleon-nucleon interaction in neutron star(NS) matter which is considered to be made up of p, e, μ and condensed antikaon matter. We mainly study the influence of the soft pion-induced potential on the nucleonic^1S_0 pairing gaps in the above NS matter. It is found that the intensities of the nucleonic ~1S_0 pairing gaps including the soft pion-induced potential are smaller than those calculated in the case of not including the soft pion-induced potential. Furthermore, the nucleonic ~1S_0 pairing gaps with the soft pion-induced potential fall into decline with the deepening of the optical potential of antikaons in the above NS matter, whereas they increase with the parameter η for the fixed optical potential of antikaons. Due to the appearance of the soft pion-induced potential, the maximum values of nucleonic ~1S_0 pairing gaps at parameter η = 0.20,0.55 are suppressed by1.7%-6.8% with respect to the case without soft pion-induced potential in the above NS matter.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB921603)the National Natural Science Foundation of China(Grant Nos.11374126,11347137,11204103,11404336,and 11204029)the Fund for Fostering Talents in Basic Science of the National Natural Science Foundation of China(Grant No.J1103202)
文摘In this work, we experimentally demonstrate an image information transfer between two channels by using slow light based on electromagnetically induced transparency（EIT） in a solid. The probe optical image is slowed due to steep dispersion induced by EIT. By applying an additional control field to an EIT-driven medium, the slowed image is transferred into two information channels. Image intensities between two information channels can be controlled by adjusting the intensities of the control fields. The similarity of output images is further analyzed. This image information transfer allows for manipulating images in a controlled fashion, and will be important in further information processing.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10774059,10904084the National Basic Research Program of China under Grant No 2006CB921103.
文摘A neatly controllable photonic band gap formed in a four-level tripod system in the solid material,Pr^(3+)-doped yttrium orthosilicate(Pr:YSO)is investigated.Driven by two standing waves,the sample is just like a photonic crystal to the weak probe.Based on the numerical simulation and the analytic result we present a clear and full-scale view on the induced band gap in the inhomogeneously broadened tripod system.
基金Supported by the National Natural Science Foundation of China
文摘The ^1 S0 nucleonic superfluids are investigated within the relativistic meanfield model and Bardeen-Cooper-Schrieffer theory in hyperonic neutron stars. The ^1 S0 pairing gaps of neutrons and protons are calculated based on the Reid soft-core interaction as the nucleon-nucleon interaction. In particular, we have studied the influence of degrees of freedom for hyperons on the ^1 S0 nucleonic pairing gap in neutron star matter. It is found that the appearance of hyperons has little impact on the baryonic density range and the size of the ^1S0 neutronic pairing gap; the ^1S0 protonic pairing gap also decreases slightly in this region where ρB = 0.0-0.393 fm^-3. However, if baryonic density becomes greater than 0.393 fm^-3, the ^1S0 protonic pairing gap obviously increases. In addition, the possible range for a protonic superfluid is obviously enlarged due to the presence of hyperons. In our results, the hyperons change the 1 So protonic pairing gap, which must change the cooling properties of neutron stars.
基金the National Natural Science Foundation of China under Grant Nos 11805022,11265009,11175077 and 11271055the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2016056
文摘The GW170817 binary neutron star merger event in 2017 has raised great interest in the theoretical research f neutron stars. The structure and cooling properties of dark-matter-admixed neutron stars are studied here using relativistic mean field theory and cooling theories. The non-self-annihilating dark matter(DM) component is assumed to be ideal fermions, among which the weak interaction is considered. The results show that pulsars J1614-2230, J0348+0432 and EXO 0748-676 may all contain DM with the particle mass of 0.2–0.4 GeV. However,it is found that the effect of DM on neutron star cooling is complicated. Light DM particles favor the fast cooling of neutron stars, and the case is converse for middle massive DM. However, high massive DM particles, around1.0 GeV, make the low mass(around solar mass) neutron star still undergo direct Urca process of nucleons at the core, which leads the DM-admixed stars cool much more quickly than the normal neutron star, and cannot support the direct Urca process with a mass lower than 1.1 times solar mass. Thus, we may conjecture that if small(around solar mass) and super cold(at least surface temperature 5–10 times lower than that of the usual observed data) pulsars are observed, then the star may contain fermionic DM with weak self-interaction.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11075063,11073033,11247312 and 11103047.
文摘In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10675024 and 11075063the National Fundamental Fund Project in Subsidy Funds of Personnel Training J0730311.
文摘Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a (∧∧) pair. The parameter set we use is in line with the recent experimental data △B_(∧∧) ~ 1.01 ± 0.20_+0.18-0.11 MeV.It is found that with σ^(*) and φ mesons the pairing energy gap △F of ∧ hyperons and the corresponding SF critical temperature T_(C∧) are suppressed.In addition the NS mass range of ∧ hyperon SF is enlarged obviously.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11075063,11073033,11247312 and 11103047.
文摘We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10675024,11075063 and 11265009the National Found for Fostering Talents of Basic Science under Grant No J1103202.
文摘We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model for CFL quark matter.In our calculation results,we find that with the increase of the CFL energy gap there exists a transition behavior,which goes from the hadron star range through the transition range into the CFL quark star range.The observation data of PRS J1614-2230 are in the hadron star range(withΔ<40MeV).We also find that with hyperons the equation of state(EOS)for the hybrid star matter with the CFL quark matter core has a small change,which can be disregarded.
基金This work was supported by the National Key Scientific Project "Crustal Movement Observation Network of China" the Knowledge Innovation Program of the Chinese Academy of Sciences.
文摘This note introduces the performance and observation summary of the SLR system at Changcun Observatory, the Chinese Academy of Sciences. The performance of the SLR system has been greatly improved since August 1997. The single shot precision is improved from 5-7 cm to 1-2 cm and the normal point precision reaches 4-7 mm. The long-term stability is better than 1 cm. The amount of observation has been increased from 1000 to over 3000 passes. The whole performance of Changcun SLR system has reached the advanced level among the worldwide SLR stations.
基金partially funded by the Horizontal Scientific Research Project of the National Astronomical Observatories of CAS(Grant No.E0900501)and the Theoretical Fundamental Research Special Project of the Changchun Observatory,National Astronomical Observatories,CAS(Grant No.Y990000205)。
文摘Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the surface gravitational redshift and the Keplerian frequency for the traditional neutron star and the hyperon star matter within the relativistic mean field theory,using the GM1 and TM1 parameter sets by considering the two flavor symmetries of SU(6)and SU(3)combined with the observations of PSR J1614-2230,PSR J0348+0432,PSR J0030+0451,RX J0720.4-3125,and 1E 1207.4-5209.It is found that the existence of dark energy leads to the softened equations of the state of the traditional neutron star and the hyperon star.The radius of a fixed-mass traditional neutron star(or hyperon star)with dark energy becomes smaller,which leads to increased compactness.The existence of dark energy can also enhance the surface gravitational redshift and the Keplerian frequency of traditional neutron stars and hyperon stars.The growth of the Keplerian frequency may cause the spin rate to speed up,which may provide a possible way to understand and explain the pulsar glitch phenomenon.Specifically,we infer that the mass and the surface gravitational redshift of PSR J1748-2446ad without dark energy for the GM1(TM1)parameter set are 1.141 M_(☉)(1.309 M_(☉))and 0.095(0.105),respectively.The corresponding values for the GM1(TM1)parameter set are 0.901 M_(☉)(1.072M_(☉))and 0.079(0.091)if PSR J1748-2446ad contains dark energy withα=0.05.PSR J1748-2446ad may be a low-mass pulsar with a lower surface gravitational redshift under our selected models.
基金supported by Natural Science Foundation of Jilin Province(20210101468JC)Chinese Academy of Sciences and Local Government Cooperation Project(2023SYHZ0027,23SH04)National Natural Science Foundation of China(12273063&12203078)。
文摘Observatories typically deploy all-sky cameras for monitoring cloud cover and weather conditions.However,many of these cameras lack scientific-grade sensors,r.esulting in limited photometric precision,which makes calculating the sky area visibility distribution via extinction measurement challenging.To address this issue,we propose the Photometry-Free Sky Area Visibility Estimation(PFSAVE)method.This method uses the standard magnitude of the faintest star observed within a given sky area to estimate visibility.By employing a pertransformation refitting optimization strategy,we achieve a high-precision coordinate transformation model with an accuracy of 0.42 pixels.Using the results of HEALPix segmentation is also introduced to achieve high spatial resolution.Comprehensive analysis based on real allsky images demonstrates that our method exhibits higher accuracy than the extinction-based method.Our method supports both manual and robotic dynamic scheduling,especially under partially cloudy conditions.
基金National Natural Science Foundation of China(NSFC)(11474132,61378004,61527823,61605058,61605219)Natural Science Foundation of Jilin Province(20160520085JH)+3 种基金Key Technology Research and Development Project of Jilin Province(20180201120GX)Major Science and Technology Tendering Project of Jilin Province(20170203012GX)Joint Foundation from Equipment Pre-research and Ministry of Education(6141A02022413)Outstanding Young Talent Fund Project of Jilin Province(20180520188JH)
文摘In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser （EDFL） by using gold nanostars （GNSs） as a saturable absorber （SA） for the first time, to the best of our knowledge. In comparison with other gold nanomorphologies, GNSs have multiple localized surface plasmon resonances, which means that they can be used to construct wideband ultrafast pulse lasers. By inserting the GNS SA into an EDFL cavity pumped by a 980 nm laser diode, a stable passively Q-switched laser at 1564.5 nm was achieved for a threshold pump power of 40 mW. By gradually increasing the pump power from 40 to 120 mW, the pulse duration decreases from 12.8 to 5.3 its and the repetition rate increases from 10 to 17 kHz. Our results indicate that the GNSs are a promising SA for constructing pulse lasers.
基金National Natural Science Foundation of China(NSFC)(61875033,61505024,61435003,61421002,61705147,61605219,61775031)Chengdu Science and Technology Huimin Project(2016-HM01-00265-SF,2016-HM01-00269-SF)Fundamental Research Funds for the Central Universities(YJ201723)
文摘We propose and demonstrate a widely tunable passively Q-switched Ho^(3+)∕Pr^(3+)-codoped ZrF_4-BaF_2-LaF_3-AlF_3-NaF fiber laser operating in the 2.8 μm mid-infrared(MIR) waveband based on a single-walled carbon nanotube(SWCNT) saturable absorber(SA). The SWCNTs have diameters ranging from 1.4 to 1.7 nm. The modulation depth and saturation intensity of the SWCNT SA measured at 2850 nm are 16.5% and 1.66 MW∕cm^2, respectively. Stable Q-switched pulses with the shortest pulse duration of 1.46 μs and the maximum pulse energy of 0.43 μJ are achieved at a launched pump power of 445.6 mW. The combined use of a broadband SWCNT SA and a plane ruled grating ensures a broad continuously tuning range of 55.0 nm from 2837.6 to 2892.6 nm.The output powers, emission spectra, repetition rates, and pulse durations at different tuning wavelengths are also characterized and analyzed. Our results indicate that SWCNTs can be excellent broadband SAs in the 3 μm MIR region. To the author's knowledge, this is the first demonstration of a widely tunable carbon-nanotubeenabled passively Q-switched fiber laser operating in the 2.8 μm MIR waveband.
基金Supported by the National Science Foundation of China under Grant No.11273013by the Natural Science Foundation of Jilin Province under Grant No.20180101228JC
文摘It is a common practice to evaluate probability density function or matter spatial density function from statistical samples. Kernel density estimation is a frequently used method, but to select an optimal bandwidth of kernel estimation, which is completely based on data samples, is a long-term issue that has not been well settled so far. There exist analytic formulae of optimal kernel bandwidth, but they cannot be applied directly to data samples,since they depend on the unknown underlying density functions from which the samples are drawn. In this work, we devise an approach to pick out the totally data-based optimal bandwidth. First, we derive correction formulae for the analytic formulae of optimal bandwidth to compute the roughness of the sample's density function. Then substitute the correction formulae into the analytic formulae for optimal bandwidth, and through iteration we obtain the sample's optimal bandwidth. Compared with analytic formulae, our approach gives very good results, with relative differences from the analytic formulae being only 2%～3% for sample size larger than 10~4. This approach can also be generalized easily to cases of variable kernel estimations.
