期刊文献+
共找到245篇文章
< 1 2 13 >
每页显示 20 50 100
Probing the Internal Physics of Neutron Stars through the Observed Braking Indices and Magnetic Tilt Angles of Several Young Pulsars
1
作者 Fang-Yuan Hu Quan Cheng +4 位作者 Xiao-Ping Zheng Jia-Qian Wang Yu-Long Yan Jia-Yu Wang Tian-Yu Luo 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第5期221-229,共9页
The braking indices of pulsars may contain important information about the internal physics of neutron stars(NSs),such as neutron superfluidity and internal magnetic fields.As a subsequent paper of Cheng et al.,we per... The braking indices of pulsars may contain important information about the internal physics of neutron stars(NSs),such as neutron superfluidity and internal magnetic fields.As a subsequent paper of Cheng et al.,we perform the same analysis as that done in the previous paper to other young pulsars with a steady braking index,n.Combining the timing data of these pulsars with the theory of magnetic field decay,and using their measured magnetic tilt angles,we can set constraints on the number of precession cycles,ξ,which represents the interactions between superfluid neutrons and other particles in the NS interior.For the pulsars considered in this paper,the results show thatξis within the range of a few×10~3 to a few×10~6.Interestingly,for the Crab and Vela pulsars,the constraints onξobtained with our method are generally consistent with that derived from modeling of the glitch rise behaviors of the two pulsars.Furthermore,we find that the internal magnetic fields of pulsar with n<3 may be dominated by the toroidal components.Our results may not only help to understand the interactions between the superfluid neutrons and other particles in the interior of NSs but also be important for the study of continuous gravitational waves from pulsars. 展开更多
关键词 stars neutron-(stars:)pulsars general-stars magnetic field-gravitational waves
下载PDF
Free Energy of Anisotropic Strangeon Stars 被引量:1
2
作者 Shichuan Chen Yong Gao +1 位作者 Enping Zhou Renxin Xu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期50-57,共8页
Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot debate... Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot debate.Enormous energy is surely needed to understand various observations,such asγ-ray bursts,fast radio bursts and softγ-ray repeaters.In this paper,the elastic/gravitational free energy of solid strangeon stars is revisited for strangeon stars,with two anisotropic models to calculate in general relativity.It is found that huge free energy(>10^(46)erg)could be released via starquakes,given an extremely small anisotropy((p_(t)-p_(r))/p_(r)~10^(-4),with pt/pr the tangential/radial pressure),implying that pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in the solid strangeon star model. 展开更多
关键词 (stars:)pulsars general-methods numerical-(stars:)gamma-ray bursts general
下载PDF
A Fermi-LAT Study of Globular Cluster Dynamical Evolution in the Milky Way:Millisecond Pulsars as the Probe
3
作者 Li Feng Zhongqun Cheng +2 位作者 Wei Wang Zhiyuan Li Yang Chen 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期1-23,共23页
Using archival Fermi-LAT data with a time span of~12 yr,we study the population of Millisecond Pulsars(MSPs)in Globular Clusters(GlCs)and investigate their dependence on cluster dynamical evolution in the Milky Way.We... Using archival Fermi-LAT data with a time span of~12 yr,we study the population of Millisecond Pulsars(MSPs)in Globular Clusters(GlCs)and investigate their dependence on cluster dynamical evolution in the Milky Way.We show that theγ-ray luminosity(L_(γ))and emissivity(i.e.,ε_(γ)=L_(γ)/M,with M the cluster mass)are good indicators of the population and abundance of MSPs in GlCs,and they are highly dependent on the dynamical evolution history of the host clusters.Specifically speaking,the dynamically older GlCs with more compact structures are more likely to have larger L_(γ)andε_(γ),and these trends can be summarized as strong correlations with cluster stellar encounter rateΓand the specific encounter rate(Λ=Γ/M),with L_(γ)∝Γ^(0.7±0.11)andε_(γ)∝Λ^(0.73±0.13)for dynamically normal GlCs.However,as GlCs evolve into deep core collapse,these trends are found to be reversed,implying that strong encounters may have lead to the disruption of Low-Mass X-ray Binaries and ejection of MSPs from core-collapsed systems.Besides,the GlCs are found to exhibit largerε_(γ)with increasing stellar mass function slope(ε_(γ)∝10^((0.52±0.1)α)),decreasing tidal radius(ε_(γ)∝R_(t)^(-10±0.22))and distances from the Galactic Center(GC,ε_(γ)∝R_(gc)^(-1.13±0.21)).These correlations indicate that,as GlCs losing kinetic energy and spiral in toward the GC,tidal stripping and mass segregation have a preference in leading to the loss of normal stars from GlCs,while MSPs are more likely to concentrate to cluster center and be deposited into the GC.Moreover,we gaugeε_(γ)of GlCs is~10-1000 times larger than the Galactic bulge,the latter is thought to reside thousands of unresolved MSPs and may be responsible for the GC 7-ray excess,which supports that GlCs are generous contributors to the population of MSPs in the GC. 展开更多
关键词 (Galaxy:)globular clusters general-(stars:)pulsars general-Galaxy kinematics and dynamics-Galaxy center-Galaxy bulge-gamma-rays stars-gamma-rays diffuse background-gamma-rays galaxies
下载PDF
Rotating Massive Strangeon Stars and X-Ray Plateau of Short GRBs
4
作者 Xi-Yan Yang Xiao-Yu Lai +1 位作者 Wei-Wei Tan Ren-Xin Xu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第3期47-57,共11页
Strangeon stars,which are proposed to describe the nature of pulsar-like compact stars,have passed various observational tests.The maximum mass of a non-rotating strangeon star could be high,which implies that the rem... Strangeon stars,which are proposed to describe the nature of pulsar-like compact stars,have passed various observational tests.The maximum mass of a non-rotating strangeon star could be high,which implies that the remnants of binary strangeon star mergers could even be long-lived massive strangeon stars.We study rigidly rotating strangeon stars in the slowly rotating approximation,using the Lennard-Jones model for the equation of state.Rotation can significantly increase the maximum mass of strangeon stars with unchanged baryon numbers,enlarging the mass-range of long-lived strangeon stars.During spin-down after merger,the decrease of radius of the remnant will lead to the release of gravitational energy.Taking into account the efficiency of converting the gravitational energy luminosity to the observed X-ray luminosity,we find that the gravitational energy could provide an alternative energy source for the plateau emission of X-ray afterglow.The fitting results of X-ray plateau emission of some short gamma-ray bursts suggest that the magnetic dipole field strength of the remnants can be much smaller than that of expected when the plateau emission is powered only by spin-down luminosity of magnetars. 展开更多
关键词 dense matter-(stars) pulsars general-(stars) gamma-ray burst GENERAL
下载PDF
Characteristics of Emission Non-nulling Pulsars Through Simulation
5
作者 Rai Yuen 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第4期91-102,共12页
We investigate the population and several properties of radio pulsars whose emission does not null(non-nulling)through simulation of a large pulsar sample.Emission from a pulsar is identified as non-nulling if(i)the e... We investigate the population and several properties of radio pulsars whose emission does not null(non-nulling)through simulation of a large pulsar sample.Emission from a pulsar is identified as non-nulling if(i)the emission does not cease across the whole pulse profile,and(ii)the emission is detectable.For(i),we adopt a model for switching in the plasma charge density,and emission persists if the charge density is non-zero.For(ii),we assume that detectable emission originates from source points where it is emitted tangentially to the magnetic field-line and parallel to the line-of-sight.We find that pulsars exhibiting non-nulling emission possess obliquity angles with an average of 42°.5,and almost half the samples maintain a duty cycle between 0.05 and 0.2.Furthermore,the pulsar population is not fixed but dependent on the obliquity angle,with the population peaking at 20°.In addition,three evolutionary phases are identified in the pulsar population as the obliquity angle evolves,with the majority of samples having an obliquity angle between 20°and 65°.Our results also suggest that emission from a pulsar may evolve between nulling and non-nulling during its lifetime. 展开更多
关键词 radiation mechanisms:non THERMAL stars:neutron (stars:)pulsars:general
下载PDF
Variable Stars in the 50BiN Open Cluster Survey.Ⅲ.NGC 884
6
作者 Lin-Hong Wang Qian-Heng Nie +5 位作者 Kun Wang Xiao-Dian Chen Chun-Guang Zhang Li-Cai Deng Xiao-Bin Zhang Tian-Lu Chen 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期36-45,共10页
Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal ... Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869. 展开更多
关键词 stars variables general-(Galaxy:)open clusters and associations individual(… …)-(stars:)binaries GENERAL
下载PDF
The Origin of Glitches in Pulsars—Phase Oscillation between Anisotropic Superfluid and Normal State of Neutrons in Neutron Stars
7
作者 Qiu-He Peng Zhi-Quan Luo Chih-Kang Chou 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2006年第3期297-304,共8页
Considering neutron star heating by magnetic dipole radiation from ^3PF2 superfluid neutron vortices inside the star, we propose a neutron phase oscillation model between the normal neutron Fermi fluid and the ^3PF2 s... Considering neutron star heating by magnetic dipole radiation from ^3PF2 superfluid neutron vortices inside the star, we propose a neutron phase oscillation model between the normal neutron Fermi fluid and the ^3PF2 superfluid neutron vortices at the transition temperature of Ttrans = (2 - 3)× 10^8 K. With this model we can qualitatively explain most of the observations on pulsar glitches up to date. 展开更多
关键词 stars neutron - pulsars general
下载PDF
FAST Pulsar Database.I.Polarization Profiles of 682 Pulsars 被引量:1
8
作者 P.F.Wang J.L.Han +6 位作者 J.Xu C.Wang Y.Yan W.C.Jing W.Q.Su D.J.Zhou T.Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第10期71-175,共105页
Pulsar polarization profiles form a very basic database for understanding the emission processes in a pulsar magnetosphere.After careful polarization calibration of the 19-beam L-band receiver and verification of beam... Pulsar polarization profiles form a very basic database for understanding the emission processes in a pulsar magnetosphere.After careful polarization calibration of the 19-beam L-band receiver and verification of beamoffset observation results,we obtain polarization profiles of 682 pulsars from observations by the Five-hundredmeter Aperture Spherical radio Telescope(FAST)duringthe Galactic Plane Pulsar Snapshot survey and other normal FAST projects.Among them,polarization profiles of about 460 pulsars are observed for the first time.The profiles exhibit diverse features.Some pulsars have a polarization position angle curve with a good S-shaped swing,some with orthogonal modes;some have components with highly linearly polarized components or strong circularly polarized components;some have a very wide profile,coming from an aligned rotator,and some have an interpulse from a perpendicular rotator;some wide profiles are caused by interstellar scattering.We derive geometric parameters for 190 pulsars from the S-shaped position angle curves or with orthogonal modes.We find that the linear and circular polarization or the widths of pulse profiles have various frequency dependencies.Pulsars with a large fraction of linear polarization are more likely to have a large Edot. 展开更多
关键词 POLARIZATION (stars:)pulsars:general astronomical databases:miscellaneous
下载PDF
The Analyses of Globular Cluster Pulsars and Their Detection Efficiency
9
作者 De-Jiang Yin Li-Yun Zhang +3 位作者 Bao-Da Li Ming-Hui Li Lei Qian Zhichen Pan 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第5期142-147,共6页
Up to 2022 November,267 pulsars had been discovered in 36 globular clusters(GCs).In this paper,we present our studies on the distribution of GC pulsar parameters and the detection efficiency.The power law relation bet... Up to 2022 November,267 pulsars had been discovered in 36 globular clusters(GCs).In this paper,we present our studies on the distribution of GC pulsar parameters and the detection efficiency.The power law relation between average dispersion measure(■)and dispersion measure difference(ΔDM)of known pulsars in GCs is lgΔDM∝1.52lg■.The sensitivity could be the key to finding more pulsars.As a result,several years after the construction of a large radio telescope facility,the number of known GC pulsars will likely be increased accordingly.We suggest that currently GCs in the southern hemisphere could have higher possibilities for finding new pulsars. 展开更多
关键词 (stars:)pulsars general-(Galaxy:)globular clusters general-stars STATISTICS
下载PDF
Searching For Wide Binary Stars with Non-coeval Components in the Southern Sky
10
作者 Alexey Kniazev Oleg Malkov 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第5期230-235,共6页
We have completed our observational program to search for wide binary systems with non-coeval components in the southern sky and report our results here.The final set of four systems was spectroscopically investigated... We have completed our observational program to search for wide binary systems with non-coeval components in the southern sky and report our results here.The final set of four systems was spectroscopically investigated in this paper.No binary systems with components of different ages were found among them.Taking into account our previous studies,we estimate the fraction of such binaries(i.e.,binaries formed,presumably,by capture)to be not higher than 0.06%.The study will be continued on the northern sky. 展开更多
关键词 (stars:)binaries general-(stars:)binaries visual-stars formation
下载PDF
Revise Thermal Winds of Remnant Neutron Stars in Gamma-Ray Bursts
11
作者 Shuang Du Tingting Lin +1 位作者 Shujin Hou Renxin Xu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第9期142-147,共6页
It seems that the wealth of information revealed by the multi-messenger observations of the binary neutron star(NS)merger event,GW170817/GRB 170817A/kilonova AT2017gfo,places irreconcilable constraints to models of th... It seems that the wealth of information revealed by the multi-messenger observations of the binary neutron star(NS)merger event,GW170817/GRB 170817A/kilonova AT2017gfo,places irreconcilable constraints to models of the prompt emission of this gamma-ray burst(GRB).The observed time delay between the merger of the two NSs and the trigger of the GRB and the thermal tail of the prompt emission can hardly be reproduced by these models simultaneously.We argue that the merger remnant should be an NS(last for,at least,a large fraction of 1 s),and that the difficulty can be alleviated by the delayed formation of the accretion disk due to the absorption of high-energy neutrinos emitted by the NS and the delayed emergence of effective viscosity in the disk.Further,we extend the consideration of the effect of the energy deposition of neutrinos emitted from the NS.If the NS is the central object of a GRB with a distance and duration similar to that of GRB 170817A,thermal emission of the thermal bubble inflated by the NS after the termination of accretion may be detectable.If our scenario is verified,it would be of interest to investigate the cooling of nascent NSs. 展开更多
关键词 (stars )gamma-ray burst general-(stars )gamma-ray burst individual(.. ...)-stars NEUTRON
下载PDF
The Variability and Radial Velocity of Planetary Nebula Central Stars
12
作者 A.Ali A.Mindil 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第4期66-71,共6页
The extremely accurate estimates of stellar variability and radial velocity in the Gaia Data Release 3(Gaia DR3)have enabled us to examine the close binarity and radial velocity(RV)of central stars(CSs)of planetary ne... The extremely accurate estimates of stellar variability and radial velocity in the Gaia Data Release 3(Gaia DR3)have enabled us to examine the close binarity and radial velocity(RV)of central stars(CSs)of planetary nebulae(PNe).This study is twofold:(1)searching for new close binary CS candidates to better understand how binarity affects the formation and evolution of PNe;and(2)extending the sample size of known RVs of PNe in order to understand their kinematics and the dynamics of the Milky Way.As a target sample,we used all true,possible,and likely PNe available in the literature.Then,we looked for their matched Gaia DR3 sources that provide measurements of variability and RV.As a result,we detected the first large collection of trustworthy photometric variability of 26 symbiotic stars and 82 CSs.In this CS group,there are 24 sources already classified as true close binary CSs in the literature.Hence,we discovered 58 new close binary CS candidates.This close binary(CB)sample represents more than half of what is currently available in the literature.In addition,we identified the radial velocities for 51 PNe.To our knowledge,24 of these were measured for the first time.The RV measurements predicted by Gaia,based on the Doppler shift of the CS absorption lines,and those derived from nebular emission lines,show satisfactory agreement except for a few extremely high-velocity PNe. 展开更多
关键词 (ISM:)planetary nebulae general-stars variables general-(stars:)binaries eclipsing-(stars:)binaries symbiotic-techniques radial velocities
下载PDF
Single-pulse Emission Variation of Two Pulsars Discovered by FAST
13
作者 Ziping Guo Zhigang Wen +14 位作者 Jianping Yuan Feifei Kou Qingdong Wu Na Wang Weiwei Zhu Di Li Mengyao Xue Pei Wang Chenchen Miao De Zhao Yue Hu Wenming Yan Jiarui Niu Rukiye Rejep Zhipeng Huang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第7期96-109,共14页
We investigate the single-pulse emission variations of two pulsars,PSRs J0211+4235 and J0553+4111,observed with the Five-hundred-meter Aperture Spherical radio Telescope at the 1.25 GHz central frequency.The observati... We investigate the single-pulse emission variations of two pulsars,PSRs J0211+4235 and J0553+4111,observed with the Five-hundred-meter Aperture Spherical radio Telescope at the 1.25 GHz central frequency.The observation sessions span from 2020 December to 2021 July,with 21 and 22 observations for them respectively.The integrated pulse profile of PSR J0211+4235 shows that there is a weak pulse component following the main component,and PSR J0553+4111 displays a bimodal profile with a bridge component in the middle.PSR J0211+4235 presents significant nulling phenomenon with nulling duration lasting from 2 to 115 pulses and burst duration lasting from 2 to 113 pulses.The NF of each observation is determined to be 45%-55%.No emission greater than threeσis found in the mean integrated profile of all nulling pulses.In most cases,the pulse energy changes abruptly during the transition from null to burst,while in the transition from burst to null there are two trends:abrupt and gradual.We find that the nulling phenomenon of PSR J0211+4235 is periodic by the Fourier transform of the null and burst state.In addition,the single-pulse modulation characteristics of these two pulsars are investigated,and the distributions of modulation index,LRFS and 2DFS are analyzed with PSRSALSA.The left peak of PSR J0553+4111 has intensity modulation.Finally,the polarization properties of these two pulsars are obtained through polarization calibration,and their characteristics are analyzed.The possible physical mechanisms of these phenomena are discussed. 展开更多
关键词 (stars:)pulsars:general (stars:)pulsars:individual(PSR J0211+4235 PSR J0553+4111) stars:neutron
下载PDF
Searching for Pulsars with Phase Characteristics
14
作者 Bo Peng Qian-Chen Hu +4 位作者 Qiang Li Lei Qian Xiao-Bo Dong Shi-Lin Peng Ze-Lin Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第1期91-99,共9页
We present a method by using the phase characteristics of radio observation data for pulsar search and candidate identification.The phase characteristics are relations between the pulsar signal and the phase correctio... We present a method by using the phase characteristics of radio observation data for pulsar search and candidate identification.The phase characteristics are relations between the pulsar signal and the phase correction in the frequency-domain,and we regard it as a new search diagnostic characteristic.Based on the phase characteristics,a search method is presented:calculating dispersion measure(DM)—frequency data to select candidate frequencies,and then confirming of candidates by using the broadband characteristics of pulsar signals.Based on this method,we performed a search test on short observation data of M15 and M71,which were observed by Five-hundredmeter Aperture Spherical radio Telescope,and some of the Galactic Plane Pulsar Snapshot survey data.Results show that it can get similar search results to PRESTO(Pulsa R Exploration and Search TOolkit)while having a faster processing speed. 展开更多
关键词 methods-data analysis-(stars:)pulsars general-stars NEUTRON
下载PDF
Resonant cyclotron scattering in pulsar magnetospheres and its application to isolated neutron stars 被引量:1
15
作者 Hao Tong Ren-Xin Xu +1 位作者 Qiu-He Peng Li-Ming Song 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2010年第6期553-568,共16页
Resonant cyclotron scattering (RCS) in pulsar magnetospheres is considered. The photon diffusion equation (Kompaneets equation) for RCS is derived. The photon system is modeled three dimensionally. Numerical calcu... Resonant cyclotron scattering (RCS) in pulsar magnetospheres is considered. The photon diffusion equation (Kompaneets equation) for RCS is derived. The photon system is modeled three dimensionally. Numerical calculations show that there exist not only up scattering but also down scattering of RCS, depending on the parameter space. RCS's possible applications to spectral energy distributions of magnetar candidates and radio quiet isolated neutron stars (INSs) are pointed out. The optical/UV excess of INSs may be caused by the down scattering of RCS. The calculations for RX J1856.5-3754 and RX J0720.4-3125 are presented and compared with their observational data. In our model, the INSs are proposed to be normal neutron stars, although the quark star hypothesis is still possible. The low pulsation amplitude of INSs is a natural consequence in the RCS model. 展开更多
关键词 radiation mechanism nonthermal -- scattering -- stars neutron -- pulsars general -- pulsars individual (RX J1856.5-3754 RX J0720.4-3125)
下载PDF
Constraining the Orbital Inclination and Companion Properties of Three Black Widow Pulsars Detected by FAST
16
作者 杜泽昕 俞云伟 +3 位作者 A-Ming Chen 王双强 周霞 郑小平 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第12期275-282,共8页
Black widows(BWs)are millisecond pulsars ablating their companion stars.The out-flowing material from the companion can block the radio emission of the pulsar,resulting in eclipses.In this paper,we construct a model f... Black widows(BWs)are millisecond pulsars ablating their companion stars.The out-flowing material from the companion can block the radio emission of the pulsar,resulting in eclipses.In this paper,we construct a model for the radio eclipse by calculating the geometry of the bow shock between the winds of the pulsar and companion,where the shock shapes the eclipsing medium but had not been described in detail in previous works.The model is further used to explain the variations of the flux density and dispersion measure of three BW pulsars(i.e.,PSR B1957+20,J2055+3829,and J2051-0827)detected by the Five-hundred-meter Aperture Spherical radio Telescope.Consequently,we constrained the parameters of the three BW systems such as the inclination angles and true anomalies of the observer as well as the mass-loss rates and wind velocity of the companion stars.With the help of these constraints,it is expected that magnetic fields of companion stars and even masses of pulsars could further be determined as some extra observation can be achieved in the future. 展开更多
关键词 (stars:)pulsars individual(PSR B1957+20 PSR J2055+3829 PSR J2051-0827)-(stars:)binaries eclipsing-stars winds-outflows
下载PDF
The EOSs and the Blatant Discrepancy in Modelling Massive Neutron Stars: Origin and a Possible Solution Method
17
作者 Ahmad A. Hujeirat Mauritz M. Wicker 《Journal of Modern Physics》 2023年第11期1458-1463,共6页
Exploring the state of ultra-cold supranuclear dense matter that makes up the cores of massive neutron stars is one of the greatest unresolved problems in modern physics. In this letter, we show that when the interior... Exploring the state of ultra-cold supranuclear dense matter that makes up the cores of massive neutron stars is one of the greatest unresolved problems in modern physics. In this letter, we show that when the interiors of pulsars are made of compressible and dissipative normal matter, the commonly used solution procedures combined with the known EOSs yield widely scattered solutions and poorly determined radii. A remarkable agreement emerges, however, if pulsars harbour cores that are made of incompressible entropy-free superfluids (SuSu-matter) embedded in flat spacetimes. Such supranuclear dense matter should condensate to form false vacua as predicated by non-perterbative QCD vacuum. The solutions here are found to be physically consistent and mathematically elegant, irrespective of the object’s mass. Based thereon, we conclude that the true masses of massive NSs may differ significantly from those revealed by direct observation. 展开更多
关键词 General Relativity pulsars Neutron stars EOSs QCD INCOMPRESSIBILITY SUPERFLUIDITY Super-Conductivity
下载PDF
Evidence for False Vacuum States inside the Cores of Massive Pulsars and the Ramification on the Measurements of Their True Masses
18
作者 Ahmad A. Hujeirat Mauritz M. Wicker 《Journal of Modern Physics》 2023年第11期1409-1425,共17页
Based on the theory and observations of glitching pulsars, we show that the ultra-cold supranuclear dense matter inside the cores of massive pulsars should condensate in vacua, as predicated by non-perturbative QCD. T... Based on the theory and observations of glitching pulsars, we show that the ultra-cold supranuclear dense matter inside the cores of massive pulsars should condensate in vacua, as predicated by non-perturbative QCD. The trapped matter here forms false vacuums embedded in flat spacetimes and completely disconnected from the outside world. Although the vacuum expectation value here vanishes, the masses and sizes of these incompressible superfluid cores are set to grow with cosmic times, in accord with the Onsager-Feynman superfluidity analysis. We apply our scenario to several well-studied pulsars, namely the Crab, Vela, PSR J0740+6620 and find that the trapped mass-contents in their cores read {0.15,0.55,0.64}, implying that their true masses are {1.55,2.35,2.72} , respectively. Based thereon, we conclude that: 1) The true masses of massive pulsars and neutron stars are much higher than detected by direct observations and, therefore, are unbounded from above, 2) The remnant of the merger event in GW170817 should be a massive NS harbouring a core with 1.66  . 展开更多
关键词 Numerical Relativity pulsars MAGNETARS Neutrons stars Black Holes Quantum Vacuum QCD Condensed Matter INCOMPRESSIBILITY SUPERFLUIDITY Super-Conductivity
下载PDF
Research on Pulsar Time Steered Atomic Time Algorithm Based on DPLL
19
作者 Ze-Hao Zheng Yang Liu +4 位作者 Dan Shen Fan Feng Jiu-Long Liu Yue-Xin Ma Xiang-Wei Zhu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第3期237-248,共12页
In today’s society,there is a wide demand for high-precision and high-stability time service in the fields of electric power,communication,transportation and finance.At present,the time standard in various countries ... In today’s society,there is a wide demand for high-precision and high-stability time service in the fields of electric power,communication,transportation and finance.At present,the time standard in various countries is mainly based on atomic clocks,but the frequency drift of atomic clocks will affect the long-term stability performance.Compared with atomic clocks,millisecond pulsars have better long-term stability and can complement with the excellent short-term stability of atomic clocks.In order to improve the long-term stability of the atomic timescale,and then improve the timing accuracy,this paper proposes an algorithm for steering the atomic clock ensemble(ACE)by ensemble pulsar time(EPT)based on digital phase locked loop(DPLL).First,the ACE and EPT are generated by the ALGOS algorithm,then the ACE is steered by EPT based on DPLL to calibrate the long-term frequency drift of the atomic clock,so that the generated steered atomic time follows both the short-term stability characteristics of ACE and the long-term stability characteristics of EPT,and finally,the steered atomic time is used to calibrate the local cesium clock.The experimental results show that the long-term stability of atomic time after steering is improved by 2 orders of magnitude compared with that before steering,and the daily drift of a local cesium clock after calibration is less than 9.47 ns in 3 yr,3 orders of magnitude higher than that before calibration on accuracy. 展开更多
关键词 (stars) pulsars general-time-methods data analysis-instabilities
下载PDF
UWLPIPE:Ultra-wide Bandwidth Low-frequency Pulsar Data Processing Pipeline
20
作者 Ya-Zhou Zhang Hai-Long Zhang +7 位作者 Jie Wang Jian Li Xin-Chen Ye Shuang-Qiang Wang Xu Du Han Wu Ting Zhang Shao-Cong Guo 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第7期145-157,共13页
For real-time processing of ultra-wide bandwidth low-frequency pulsar baseband data,we designed and implemented an ultra-wide bandwidth low-frequency pulsar data processing pipeline(UWLPIPE)based on the shared ringbuf... For real-time processing of ultra-wide bandwidth low-frequency pulsar baseband data,we designed and implemented an ultra-wide bandwidth low-frequency pulsar data processing pipeline(UWLPIPE)based on the shared ringbuffer and GPU parallel technology.UWLPIPE runs on the GPU cluster and can simultaneously receive multiple 128 MHz dual-polarization VDIF data packets preprocessed by the front-end FPGA.After aligning the dual-polarization data,multiple 128M subband data are packaged into PSRDADA baseband data or multi-channel coherent dispersion filterbank data,and multiple subband filterbank data can be spliced into wideband data after time alignment.We used the Nanshan 26 m radio telescope with the L-band receiver at964~1732 MHz to observe multiple pulsars.Finally,we processed the data using DSPSR software,and the results showed that each subband could correctly fold out the pulse profile,and the wideband pulse profile accumulated by multiple subbands could be correctly aligned. 展开更多
关键词 (stars)pulsars general-methods data analysis-techniques MISCELLANEOUS
下载PDF
上一页 1 2 13 下一页 到第
使用帮助 返回顶部