Complex Field Theory (CFT) proposes that dark matter (DM) and dark energy (DE) are pervasive, complex fields of charged complex masses of equally positive and negative complex charges, respectively. It proposes that e...Complex Field Theory (CFT) proposes that dark matter (DM) and dark energy (DE) are pervasive, complex fields of charged complex masses of equally positive and negative complex charges, respectively. It proposes that each material object, including living creatures, is concomitant with a fraction of the charged complex masses of DM and DE in proportion to its mass. This perception provides new insights into the physics of nature and its constituents from subatomic to cosmic scales. This complex nature of DM and DE explains our inability to see DM or harvest DE for the last several decades. The positive complex DM is responsible for preserving the integrity of galaxies and all material systems. The negative complex charged DE induces a positive repelling force with the positively charged DM and contributes to the universe’s expansion. Both fields are Lorentz invariants in all directions and entangle the whole universe. The paper uses CFT to investigate zero-point energy, particle-wave duality, relativistic mass increase, and entanglement phenomenon and unifies Coulomb’s and Newton’s laws. The paper also verifies the existence of tachyons and explains the spooky action of quantum mechanics at a distance. The paper encourages further research into how CFT might resolve several physical mysteries in physics.展开更多
Understanding the nature of dark matter remains one of the most enigmatic and unresolved issues in astrophysics.Certain theoretical models address this by introducing a novel component to account for dark matter.In th...Understanding the nature of dark matter remains one of the most enigmatic and unresolved issues in astrophysics.Certain theoretical models address this by introducing a novel component to account for dark matter.In this study,we propose a new scalar field derived from string T-duality,where its associated density represents the density of the surrounding matter field,in the spherically symmetric and static medium.Our exploration reveals that this scalar field behaves as the baryonic fluid,characterized by a positive effective state equation,ωe>0.Furthermore,a detailed investigation demonstrates that this model satisfies all energy conditions beyond the event horizon of a central black hole.Considering the light deflection and radar echo delay suggests that in this scalar field,the dark matter grows up in the halo and surrounding regions of galaxy systems.This indicates that dark matter accumulates as an effective field outside the observable regions of galaxies.展开更多
In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the...In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.展开更多
While cold dark matter is widely supported by a range of cosmological observations,it encounters several difficulties at smaller scales.These issues have prompted the investigation of various alternative dark matter c...While cold dark matter is widely supported by a range of cosmological observations,it encounters several difficulties at smaller scales.These issues have prompted the investigation of various alternative dark matter candidates,leaving the question“What is dark matter?”still open.In this work,we propose a new cosmological model that considers dark matter as a barotropic fluid with a constant equation of state parameter and interprets dark energy as the phenomenological emergent dark energy rather than a cosmological constant.We then place constraints on our new model using the Planck 2018 Cosmic Microwave Background(CMB)anisotropy measurements,Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument(DESI),the Pantheon Plus(PP)compilation of Type Ia supernovae,and the Redshift Space Distortions(RSD)data from Gold 2018.The results show statistically significant signal for positive dark matter equation of state and square of sound speed w_(dm)=c_(s,dm)^(2)(10^(7) w_(dm)=4.0_(-2.3)^(+2.5)at the 95%confidence level)for the data combination CMB+DESI+PP+RSD.However,Bayesian evidence indicates that this data combination favors theΛCDM model with very strong evidence.展开更多
Primordial black holes(PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of...Primordial black holes(PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of turbulences in the very early universe in sustaining intense and persistent fluctuations in energy or mass density,which could provide a natural mechanism for PBH formation in the primordial universe. We analyze the mass range and abundance of PBHs produced in the magnetohydrodynamic turbulence induced by the electroweak phase transition. Remarkably, we find that the mass range of the produced PBHs falls within the most viable“asteroid mass” window from the present-day observations, and within natural parameter regions their abundance can be sufficiently large. These findings suggest that PBHs produced during magnetohydrodynamic turbulence in the very early universe may comprise a dominant part of dark matter.展开更多
The axion,a leading dark matter(DM)candidate,can convert to photons in neutron star(NS)magnetospheres via the Primakoff effect,producing narrow-band radio emission that may be detected with high-sensitivity radio tele...The axion,a leading dark matter(DM)candidate,can convert to photons in neutron star(NS)magnetospheres via the Primakoff effect,producing narrow-band radio emission that may be detected with high-sensitivity radio telescopes.Previous studies searched for axion DM-induced signals from the isolated NS J0806.4-4123 using observations of the Meer KAT UHF band(544–1088 MHz),but excluded the 1051–1088 MHz subband to mitigate potential sideband contamination.To probe this unexplored parameter space,we reprocessed the 1000–1088 MHz subband data using optimized radio frequency interference(RFI)flagging and meticulous sideband calibration.The flux stability of the calibrators and the consistency with Meer KAT’s system equivalent flux density confirmed the reliability of the data within the 1000–1080 MHz range,while the 1080–1088 MHz subband was omitted due to flux anomalies.No significant signals exceeding 5σsignificance were detected within the axion mass range of 4.136–4.467μe V(1000–1080 MHz),including the previously unprobed range 4.347–4.467μe V(1051–1080 MHz).Our null detection sets new stringent constraints with Meer KAT NS data,excluding axion-photon couplings|g_(aγγ)|?8.2×10^(-12)Ge V^(-1)at the 95%confidence level for DM masses between 4.347 and 4.467μe V.展开更多
We examine the consequences of the dark matter halo presence on the alignment of angular momenta of the luminous astronomical objects like galaxies and their clusters.For that we calculate the distribution function of...We examine the consequences of the dark matter halo presence on the alignment of angular momenta of the luminous astronomical objects like galaxies and their clusters.For that we calculate the distribution function of their gravitational fields within the statistical method,generalized to the the presence of dark matter halos.The generalization deals both with direct account for halo component in the form of Navarro,Frenk and White(NFW)profile and indirect influence of dark matter on the tidal interaction between luminous objects.The NFW profile s gravitational field distribution isolates luminous objects within the halo,suppressing mutual interactions,which contradicts observational data and simulations.To address this,we propose a hypothetical short-range interaction,which can be a well of Newtonian(gravitational)nature.Namely,we derive this short-range interaction on the basis of a multipole expansion of the initial Newtonian interaction.Introducing the short-range part in the initial interaction,we arrive at modified quadrupolar intergalaxy interaction,which permits the luminous objects,which are closer than interaction range rc,to effectively interact with each other inside the dark matter halo.This permits us to show that the more clumpy the luminous objects are,the more probably their orbital moments will be aligned.Our theoretical analysis,supported by observational and simulation data(Illustris Project 2013),indicates that dark matter halos significantly alter the gravitational field distribution,affecting angular momenta alignment.We find that while angular momenta alignment increases with cluster richness in galaxy clusters,it does not in superclusters,likely due to the abundant dark matter in superclusters.Our theoretical predictions align well with both observational data and numerical simulations.展开更多
This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE...This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE THINGS in 3D catalogs.Utilizing the Markov Chain Monte Carlo(MCMC)method for model fitting and Bayesian Information Criterion for model comparison,we find that compared to CDM,both FDM and SIDM haloes generally provide better fits to the observed rotation curves.Our findings reveal that the concentration–mass relation derived from the dark matter-only simulations is not followed by concentrations or masses obtained from the rotation curve data.Our analysis highlights a positive correlation between the core sizes of FDM and SIDM haloes and the effective radius of the galaxy,attributable to gravitational couplings between baryonic and dark matter components.Moreover,our exploration of dark matter fractions at characteristic radii indicates considerable diversity in dark matter distributions across dwarf galaxies.Notably,FDM and SIDM exhibit greater diversity than CDM in this respect.展开更多
In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and...In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and the disk region by the well established exponential profile.In order to understand the distribution of dark matter in the halo region,we consider three different dark matter profiles in the framework of the standardΛCDM model namely,Navarro-Frenk-White(NFW),Hernquist and Einasto profiles.We use recent data sets of rotation curves of the Milky Way and Andromeda galaxy.The data consist of rotation velocities of the stars and gas in the galaxy as a function of the radial distance from the center.Using Bayesian statistics,we perform an overall fit including all the components,i.e.,bulge,disk and halo with the data.Our results indicate that the NFW and Hernquist profiles are in concordance with the observational data points.However,the Einasto profile poorly explains the behavior of dark matter in both the galaxies.展开更多
The Dark Matter Particle Explorer(DAMPE) mission is one of the five scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Science(CAS) appro...The Dark Matter Particle Explorer(DAMPE) mission is one of the five scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Science(CAS) approved in 2011. The main scientific objective of DAMPE is to detect electrons and photons in the range of 5 GeV–10 TeV with unprecedented energy resolution(1.5% at 100 GeV) in order to identify possible Dark Matter(DM) signatures. It will also measure the flux of nuclei up to above 500 TeV with excellent energy resolution(40% at 800 GeV), which will bring new insights to the origin and propagation high energy cosmic rays. With its excellent photon detection capability, the DAMPE mission is well placed for new discoveries in high energy-ray astronomy as well.展开更多
Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sampl...Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sample. Fitting the rotation curves, we obtain the root-mean-square (rms) velocity and density of dark matter in the core of the galaxies. We then calculate the rms velocity vhrms (1) that dark matter particles would have if expanded adiabatically from the core of the galaxies to the present mean density of dark matter in the universe. We obtain this “adiabatic invariant” vhrms (1) for 40 spiral galaxies. The distribution of vhrms (1) has a mean 0.87 km/s and a standard deviation of 0.27 km/s. This low relative dispersion is noteworthy given the wide range of the properties of these galaxies. The adiabatic invariant vhrms (1) may, therefore, have a cosmological origin. In this case, the rms velocity of non-relativistic dark matter particles in the early universe when density perturbations are still linear is vhrms (a)=vhrms (1)/a, where a is the expansion parameter. The adiabatic invariant obtains the ratio of dark matter temperature Th (a) to mass mh in the early universe.展开更多
We restudy the Lee-Weinberg time-evolution equation including the R-parity violation. We carefullyanalyze the intluence of the boundary conditions, equation of state, SUSY parameters, especially the R-parity violation...We restudy the Lee-Weinberg time-evolution equation including the R-parity violation. We carefullyanalyze the intluence of the boundary conditions, equation of state, SUSY parameters, especially the R-parity violation,and other factors on the time-evolution of the SUSY cold dark matter. Our numerical results show that without Rparity violation, only two ranges 20 ＜ mx01 ＜ 30 GeV and 75 ＜ mx01 ＜ 110 GeV can be consistent with data, if30 ＜ mx01 ＜ 75 GeV, there must be at least two kinds of heavy particles contributing to the cold dark matter. However,with the R-parity violation, the heavy neutralino can be dark matter constituent, but it must decay and the R-parityviolation parameter is constrained by the present data.展开更多
Within the context of the Littlest Higgs model with T-parity, the heavy photon （AH） is supposed to be an ideM dark matter （DM） candidate. One direct proof of validity of the model is to produce the heavy photon at...Within the context of the Littlest Higgs model with T-parity, the heavy photon （AH） is supposed to be an ideM dark matter （DM） candidate. One direct proof of validity of the model is to produce the heavy photon at collider. In this paper, we investigate the associated production of a photon with heavy photon pair at the planned international e＋ e- linear collider （ILC）, i.e., e＋e- → AHAHγ and show the distributions of the transverse momenta of the photon. The numerical results indicate that the heavy photon production rate could reach severaL fb at the low mass parameter space and the characteristic signal is a single high energetic photon and missing energy, carried by the heavy photons. All in a/l, it can be a good chance to observe the heavy photon via this process with the high yearly luminosity of the ILC.展开更多
Hypersphere World-Universe Model (WUM) envisions Matter carried from Universe into World from fourth spatial dimension by Dark Matter Particles (DMPs). Luminous Matter is byproduct of Dark Matter (DM) annihilation. WU...Hypersphere World-Universe Model (WUM) envisions Matter carried from Universe into World from fourth spatial dimension by Dark Matter Particles (DMPs). Luminous Matter is byproduct of Dark Matter (DM) annihilation. WUM introduces Dark Epoch (spanning from Beginning of World for 0.4 billion years) when only DMPs existed, and Luminous Epoch (ever since for 13.8 billion years). Big Bang discussed in standard cosmological model is, in our view, transition from Dark Epoch to Luminous Epoch due to Rotational Fission of Overspinning DM Supercluster’s Cores and annihilation of DMPs. WUM solves a number of physical problems in contemporary Cosmology and Astrophysics through DMPs and their interactions: Angular Momentum problem in birth and subsequent evolution of Galaxies and Extrasolar systems—how do they obtain it;Fermi Bubbles—two large structures in gamma-rays and X-rays above and below Galactic center;Mysterious Star KIC 8462852 with irregular dimmings;Coronal Heating problem in solar physics—temperature of Sun’s corona exceeding that of photosphere by millions of degrees;Cores of Sun and Earth rotating faster than their surfaces;Diversity of Gravitationally-Rounded Objects in Solar system and their Internal Heat;Lightning Initiation problem—electric fields observed inside thunderstorms are not sufficient to initiate sparks;Terrestrial Gamma-Ray Flashes—bursts of high energy X-rays and gamma rays emanating from Earth. Model makes predictions pertaining to Masses of DMPs, proposes New Types of their Interactions. WUM reveals Inter-Connectivity of Primary Cosmological Parameters and calculates their values, which are in good agreement with the latest results of their measurements.展开更多
A two-dimensional Brans-Dicke star model with exotic matter and dark energy is studied in this paper,the field equation and balance equation are derived at finite temperature,the analytic solutions of these equations ...A two-dimensional Brans-Dicke star model with exotic matter and dark energy is studied in this paper,the field equation and balance equation are derived at finite temperature,the analytic solutions of these equations canbe used to calculate the mass of star.In addition,we find that star's mass has a minimum when matter state parameterγ→0.展开更多
To constrain the properties of dark matter, we study spiral galaxy rotation curves measured by the THINGS collaboration. A model that describes a mixture of two self-gravitating non-relativistic ideal gases, “baryons...To constrain the properties of dark matter, we study spiral galaxy rotation curves measured by the THINGS collaboration. A model that describes a mixture of two self-gravitating non-relativistic ideal gases, “baryons” and “dark matter”, reproduces the measured rotation curves within observational uncertainties. The model has four parameters that are obtained by minimizing a x2 between the measured and calculated rotation curves. From these four parameters, we calculate derived galaxy parameters. We find that dark matter satisfies the Boltzmann distribution. The onset of Fermi-Dirac or Bose-Einstein degeneracy obtains disagreement with observations and we determine, with 99% confidence, that the mass of dark matter particles is mh> 16 eV if fermions, or mh> 45 eV if bosons. We measure the root-mean-square velocity of dark matter particles in the spiral galaxies. This observable is of cosmological origin and allows us to obtain the root-mean-square velocity of dark matter particles in the early universe when perturbations were still linear. Extrapolating to the past we obtain the expansion parameter at which dark matter particles become non-relativistic: ahNR=[4.17±0.34(STAT)±2.50(SYST)]×10−6. Knowing we then obtain the dark matter particle mass mh=69.0±4.2(stat)±31.0(syst)eV, and the ratio of dark matter-to-photon temperature Th/T=0.389±0.008(stat)±0.058(syst) after e+e−annihilation while dark matter remains ultra-relativistic. We repeat these measurements with ten galaxies with masses that span three orders of magnitude, and angular momenta that span five orders of magnitude, and obtain fairly consistent results. We conclude that dark matter was once in thermal equilibrium with the (pre?) Standard Model particles (hence the observed Boltzmann distribution) and then decoupled from the Standard Model and from self-annihilation at temperatures above mμ. These results disfavor models with freeze-out or freeze-in. We also measure the primordial amplitude of vector modes, and constrain the baryon-dark matter cross-section: . Finally, we consider sterile Majorana neutrinos as a dark matter candidate.展开更多
The GeV-TeV -γ-ray line signal is the smoking gun signature of dark matter annihilation or decay. The detection of such a signal is one of the main targets of some space-based telescopes, including Fermi-LAT and the ...The GeV-TeV -γ-ray line signal is the smoking gun signature of dark matter annihilation or decay. The detection of such a signal is one of the main targets of some space-based telescopes, including Fermi-LAT and the upcoming missions CALET, DAMPE and Gamma-400. An important feature of γ-ray line photons that originate from dark-matter-annihilation is that they are concentrated at the center of the Galaxy. So far, no reliable γ-ray line has been detected by Fermi-LAT, and the upper limits on the cross section of annihilation into ＂y-rays have been reported. We use these upper limits to estimate the ＂maximal＂ number of -y-ray line photons detectable for Fermi- LAT, DAMPE and Gamma-400, and then investigate the spatial distribution of these photons. We show that the center of the distribution will usually be offset from the Galactic center （Sgr A＊） due to the limited statistics. Such a result is almost indepen- dent of models of the dark matter distribution, and will render the reconstruction of the dark matter distribution with the γ-ray line signal very challenging for foreseeable space-based detectors.展开更多
Detailed and redundant measurements of dark matter properties have recently become available. To describe the observations we consider scalar, vector and sterile neutrino dark matter models. A model with vector dark m...Detailed and redundant measurements of dark matter properties have recently become available. To describe the observations we consider scalar, vector and sterile neutrino dark matter models. A model with vector dark matter is consistent with all current observations.展开更多
We compare the observed galaxy stellar mass distributions in the redshift range <img src="Edit_bc01f6dd-d7f9-42f9-9db0-dbd1148de50e.png" alt="" />with expectations of the cold ΛCDM and warm ...We compare the observed galaxy stellar mass distributions in the redshift range <img src="Edit_bc01f6dd-d7f9-42f9-9db0-dbd1148de50e.png" alt="" />with expectations of the cold ΛCDM and warm ΛWDM dark matter models, and obtain the warm dark matter cut-off wavenumber: <img src="Edit_ab3d491d-7145-4d59-b4b1-bea473d62333.png" alt="" />. This result is in agreement with the independent measurements with spiral galaxy rotation curves, confirms that <em>k</em><sub>fs</sub> is due to warm dark matter free-streaming, and is consistent with the scenario of dark matter with no freeze-in and no freeze-out. Detailed properties of warm dark matter can be derived from <em>k</em><sub>fs</sub>. The data disfavors the ΛCDM model.展开更多
Compton scattering with bound electrons contributes to a significant atomic effect in low-momentum transfer,yielding background structures in direct light dark matter searches as well as low-energy rare event experime...Compton scattering with bound electrons contributes to a significant atomic effect in low-momentum transfer,yielding background structures in direct light dark matter searches as well as low-energy rare event experiments.We report the measurement of Compton scattering in low-momentum transfer by implementing a 10-g germanium detector bombarded by a^(137)Cs source with a radioactivity of 8.7 mCi and a scatter photon captured by a cylindrical NaI(Tl)detector.A fully relativistic impulse approximation combined with multi-configuration Dirac–Fock wavefunctions was evaluated,and the scattering function of Geant4 software was replaced by our calculation results.Our measurements show that the Livermore model with the modified scattering function in Geant4 is in good agreement with the experimental data.It is also revealed that atomic many-body effects significantly influence Compton scattering for low-momentum transfer(sub-keV energy transfer).展开更多
文摘Complex Field Theory (CFT) proposes that dark matter (DM) and dark energy (DE) are pervasive, complex fields of charged complex masses of equally positive and negative complex charges, respectively. It proposes that each material object, including living creatures, is concomitant with a fraction of the charged complex masses of DM and DE in proportion to its mass. This perception provides new insights into the physics of nature and its constituents from subatomic to cosmic scales. This complex nature of DM and DE explains our inability to see DM or harvest DE for the last several decades. The positive complex DM is responsible for preserving the integrity of galaxies and all material systems. The negative complex charged DE induces a positive repelling force with the positively charged DM and contributes to the universe’s expansion. Both fields are Lorentz invariants in all directions and entangle the whole universe. The paper uses CFT to investigate zero-point energy, particle-wave duality, relativistic mass increase, and entanglement phenomenon and unifies Coulomb’s and Newton’s laws. The paper also verifies the existence of tachyons and explains the spooky action of quantum mechanics at a distance. The paper encourages further research into how CFT might resolve several physical mysteries in physics.
文摘Understanding the nature of dark matter remains one of the most enigmatic and unresolved issues in astrophysics.Certain theoretical models address this by introducing a novel component to account for dark matter.In this study,we propose a new scalar field derived from string T-duality,where its associated density represents the density of the surrounding matter field,in the spherically symmetric and static medium.Our exploration reveals that this scalar field behaves as the baryonic fluid,characterized by a positive effective state equation,ωe>0.Furthermore,a detailed investigation demonstrates that this model satisfies all energy conditions beyond the event horizon of a central black hole.Considering the light deflection and radar echo delay suggests that in this scalar field,the dark matter grows up in the halo and surrounding regions of galaxy systems.This indicates that dark matter accumulates as an effective field outside the observable regions of galaxies.
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(grant No.2024A1515012573)National key R&D Program of China(grant No.2020YFC2201600)+1 种基金National Natural Science Foundation of China(NSFC,grant No.12073088)National SKA Program of China(grant No.2020SKA0110402)。
文摘While cold dark matter is widely supported by a range of cosmological observations,it encounters several difficulties at smaller scales.These issues have prompted the investigation of various alternative dark matter candidates,leaving the question“What is dark matter?”still open.In this work,we propose a new cosmological model that considers dark matter as a barotropic fluid with a constant equation of state parameter and interprets dark energy as the phenomenological emergent dark energy rather than a cosmological constant.We then place constraints on our new model using the Planck 2018 Cosmic Microwave Background(CMB)anisotropy measurements,Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument(DESI),the Pantheon Plus(PP)compilation of Type Ia supernovae,and the Redshift Space Distortions(RSD)data from Gold 2018.The results show statistically significant signal for positive dark matter equation of state and square of sound speed w_(dm)=c_(s,dm)^(2)(10^(7) w_(dm)=4.0_(-2.3)^(+2.5)at the 95%confidence level)for the data combination CMB+DESI+PP+RSD.However,Bayesian evidence indicates that this data combination favors theΛCDM model with very strong evidence.
基金supported by the International Partnership Program of the Chinese Academy of Sciences (Grant No.025GJHZ2023106GC)。
文摘Primordial black holes(PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of turbulences in the very early universe in sustaining intense and persistent fluctuations in energy or mass density,which could provide a natural mechanism for PBH formation in the primordial universe. We analyze the mass range and abundance of PBHs produced in the magnetohydrodynamic turbulence induced by the electroweak phase transition. Remarkably, we find that the mass range of the produced PBHs falls within the most viable“asteroid mass” window from the present-day observations, and within natural parameter regions their abundance can be sufficiently large. These findings suggest that PBHs produced during magnetohydrodynamic turbulence in the very early universe may comprise a dominant part of dark matter.
基金supported by the National Natural Science Foundation of China(NSFC,grant No.12220101003)the Leading Innovation and Entrepreneurship Team of Zhejiang Province of China(grant No.2023R01008)the National Key R&D Program of China No.2023YFE0110500。
文摘The axion,a leading dark matter(DM)candidate,can convert to photons in neutron star(NS)magnetospheres via the Primakoff effect,producing narrow-band radio emission that may be detected with high-sensitivity radio telescopes.Previous studies searched for axion DM-induced signals from the isolated NS J0806.4-4123 using observations of the Meer KAT UHF band(544–1088 MHz),but excluded the 1051–1088 MHz subband to mitigate potential sideband contamination.To probe this unexplored parameter space,we reprocessed the 1000–1088 MHz subband data using optimized radio frequency interference(RFI)flagging and meticulous sideband calibration.The flux stability of the calibrators and the consistency with Meer KAT’s system equivalent flux density confirmed the reliability of the data within the 1000–1080 MHz range,while the 1080–1088 MHz subband was omitted due to flux anomalies.No significant signals exceeding 5σsignificance were detected within the axion mass range of 4.136–4.467μe V(1000–1080 MHz),including the previously unprobed range 4.347–4.467μe V(1051–1080 MHz).Our null detection sets new stringent constraints with Meer KAT NS data,excluding axion-photon couplings|g_(aγγ)|?8.2×10^(-12)Ge V^(-1)at the 95%confidence level for DM masses between 4.347 and 4.467μe V.
文摘We examine the consequences of the dark matter halo presence on the alignment of angular momenta of the luminous astronomical objects like galaxies and their clusters.For that we calculate the distribution function of their gravitational fields within the statistical method,generalized to the the presence of dark matter halos.The generalization deals both with direct account for halo component in the form of Navarro,Frenk and White(NFW)profile and indirect influence of dark matter on the tidal interaction between luminous objects.The NFW profile s gravitational field distribution isolates luminous objects within the halo,suppressing mutual interactions,which contradicts observational data and simulations.To address this,we propose a hypothetical short-range interaction,which can be a well of Newtonian(gravitational)nature.Namely,we derive this short-range interaction on the basis of a multipole expansion of the initial Newtonian interaction.Introducing the short-range part in the initial interaction,we arrive at modified quadrupolar intergalaxy interaction,which permits the luminous objects,which are closer than interaction range rc,to effectively interact with each other inside the dark matter halo.This permits us to show that the more clumpy the luminous objects are,the more probably their orbital moments will be aligned.Our theoretical analysis,supported by observational and simulation data(Illustris Project 2013),indicates that dark matter halos significantly alter the gravitational field distribution,affecting angular momenta alignment.We find that while angular momenta alignment increases with cluster richness in galaxy clusters,it does not in superclusters,likely due to the abundant dark matter in superclusters.Our theoretical predictions align well with both observational data and numerical simulations.
基金financially supporting this research through PPMI KK 2024 Program,contract number 616BO/IT1.C02/KU/2024。
文摘This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE THINGS in 3D catalogs.Utilizing the Markov Chain Monte Carlo(MCMC)method for model fitting and Bayesian Information Criterion for model comparison,we find that compared to CDM,both FDM and SIDM haloes generally provide better fits to the observed rotation curves.Our findings reveal that the concentration–mass relation derived from the dark matter-only simulations is not followed by concentrations or masses obtained from the rotation curve data.Our analysis highlights a positive correlation between the core sizes of FDM and SIDM haloes and the effective radius of the galaxy,attributable to gravitational couplings between baryonic and dark matter components.Moreover,our exploration of dark matter fractions at characteristic radii indicates considerable diversity in dark matter distributions across dwarf galaxies.Notably,FDM and SIDM exhibit greater diversity than CDM in this respect.
基金supported by the Startup Research Fund of the Henan Academy of Sciences under grant No.241841219。
文摘In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and the disk region by the well established exponential profile.In order to understand the distribution of dark matter in the halo region,we consider three different dark matter profiles in the framework of the standardΛCDM model namely,Navarro-Frenk-White(NFW),Hernquist and Einasto profiles.We use recent data sets of rotation curves of the Milky Way and Andromeda galaxy.The data consist of rotation velocities of the stars and gas in the galaxy as a function of the radial distance from the center.Using Bayesian statistics,we perform an overall fit including all the components,i.e.,bulge,disk and halo with the data.Our results indicate that the NFW and Hernquist profiles are in concordance with the observational data points.However,the Einasto profile poorly explains the behavior of dark matter in both the galaxies.
文摘The Dark Matter Particle Explorer(DAMPE) mission is one of the five scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Science(CAS) approved in 2011. The main scientific objective of DAMPE is to detect electrons and photons in the range of 5 GeV–10 TeV with unprecedented energy resolution(1.5% at 100 GeV) in order to identify possible Dark Matter(DM) signatures. It will also measure the flux of nuclei up to above 500 TeV with excellent energy resolution(40% at 800 GeV), which will bring new insights to the origin and propagation high energy cosmic rays. With its excellent photon detection capability, the DAMPE mission is well placed for new discoveries in high energy-ray astronomy as well.
文摘Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sample. Fitting the rotation curves, we obtain the root-mean-square (rms) velocity and density of dark matter in the core of the galaxies. We then calculate the rms velocity vhrms (1) that dark matter particles would have if expanded adiabatically from the core of the galaxies to the present mean density of dark matter in the universe. We obtain this “adiabatic invariant” vhrms (1) for 40 spiral galaxies. The distribution of vhrms (1) has a mean 0.87 km/s and a standard deviation of 0.27 km/s. This low relative dispersion is noteworthy given the wide range of the properties of these galaxies. The adiabatic invariant vhrms (1) may, therefore, have a cosmological origin. In this case, the rms velocity of non-relativistic dark matter particles in the early universe when density perturbations are still linear is vhrms (a)=vhrms (1)/a, where a is the expansion parameter. The adiabatic invariant obtains the ratio of dark matter temperature Th (a) to mass mh in the early universe.
文摘We restudy the Lee-Weinberg time-evolution equation including the R-parity violation. We carefullyanalyze the intluence of the boundary conditions, equation of state, SUSY parameters, especially the R-parity violation,and other factors on the time-evolution of the SUSY cold dark matter. Our numerical results show that without Rparity violation, only two ranges 20 ＜ mx01 ＜ 30 GeV and 75 ＜ mx01 ＜ 110 GeV can be consistent with data, if30 ＜ mx01 ＜ 75 GeV, there must be at least two kinds of heavy particles contributing to the cold dark matter. However,with the R-parity violation, the heavy neutralino can be dark matter constituent, but it must decay and the R-parityviolation parameter is constrained by the present data.
基金Supported by the National Natural Science Foundation of China under Grant No.11075045the Natural Science Foundation of Education Department of Henan Province under Grant No.2011A140005
文摘Within the context of the Littlest Higgs model with T-parity, the heavy photon （AH） is supposed to be an ideM dark matter （DM） candidate. One direct proof of validity of the model is to produce the heavy photon at collider. In this paper, we investigate the associated production of a photon with heavy photon pair at the planned international e＋ e- linear collider （ILC）, i.e., e＋e- → AHAHγ and show the distributions of the transverse momenta of the photon. The numerical results indicate that the heavy photon production rate could reach severaL fb at the low mass parameter space and the characteristic signal is a single high energetic photon and missing energy, carried by the heavy photons. All in a/l, it can be a good chance to observe the heavy photon via this process with the high yearly luminosity of the ILC.
文摘Hypersphere World-Universe Model (WUM) envisions Matter carried from Universe into World from fourth spatial dimension by Dark Matter Particles (DMPs). Luminous Matter is byproduct of Dark Matter (DM) annihilation. WUM introduces Dark Epoch (spanning from Beginning of World for 0.4 billion years) when only DMPs existed, and Luminous Epoch (ever since for 13.8 billion years). Big Bang discussed in standard cosmological model is, in our view, transition from Dark Epoch to Luminous Epoch due to Rotational Fission of Overspinning DM Supercluster’s Cores and annihilation of DMPs. WUM solves a number of physical problems in contemporary Cosmology and Astrophysics through DMPs and their interactions: Angular Momentum problem in birth and subsequent evolution of Galaxies and Extrasolar systems—how do they obtain it;Fermi Bubbles—two large structures in gamma-rays and X-rays above and below Galactic center;Mysterious Star KIC 8462852 with irregular dimmings;Coronal Heating problem in solar physics—temperature of Sun’s corona exceeding that of photosphere by millions of degrees;Cores of Sun and Earth rotating faster than their surfaces;Diversity of Gravitationally-Rounded Objects in Solar system and their Internal Heat;Lightning Initiation problem—electric fields observed inside thunderstorms are not sufficient to initiate sparks;Terrestrial Gamma-Ray Flashes—bursts of high energy X-rays and gamma rays emanating from Earth. Model makes predictions pertaining to Masses of DMPs, proposes New Types of their Interactions. WUM reveals Inter-Connectivity of Primary Cosmological Parameters and calculates their values, which are in good agreement with the latest results of their measurements.
基金Supported by the Natural Science Foundation of Sichuan Education Committee under Grant No.08ZA038
文摘A two-dimensional Brans-Dicke star model with exotic matter and dark energy is studied in this paper,the field equation and balance equation are derived at finite temperature,the analytic solutions of these equations canbe used to calculate the mass of star.In addition,we find that star's mass has a minimum when matter state parameterγ→0.
文摘To constrain the properties of dark matter, we study spiral galaxy rotation curves measured by the THINGS collaboration. A model that describes a mixture of two self-gravitating non-relativistic ideal gases, “baryons” and “dark matter”, reproduces the measured rotation curves within observational uncertainties. The model has four parameters that are obtained by minimizing a x2 between the measured and calculated rotation curves. From these four parameters, we calculate derived galaxy parameters. We find that dark matter satisfies the Boltzmann distribution. The onset of Fermi-Dirac or Bose-Einstein degeneracy obtains disagreement with observations and we determine, with 99% confidence, that the mass of dark matter particles is mh> 16 eV if fermions, or mh> 45 eV if bosons. We measure the root-mean-square velocity of dark matter particles in the spiral galaxies. This observable is of cosmological origin and allows us to obtain the root-mean-square velocity of dark matter particles in the early universe when perturbations were still linear. Extrapolating to the past we obtain the expansion parameter at which dark matter particles become non-relativistic: ahNR=[4.17±0.34(STAT)±2.50(SYST)]×10−6. Knowing we then obtain the dark matter particle mass mh=69.0±4.2(stat)±31.0(syst)eV, and the ratio of dark matter-to-photon temperature Th/T=0.389±0.008(stat)±0.058(syst) after e+e−annihilation while dark matter remains ultra-relativistic. We repeat these measurements with ten galaxies with masses that span three orders of magnitude, and angular momenta that span five orders of magnitude, and obtain fairly consistent results. We conclude that dark matter was once in thermal equilibrium with the (pre?) Standard Model particles (hence the observed Boltzmann distribution) and then decoupled from the Standard Model and from self-annihilation at temperatures above mμ. These results disfavor models with freeze-out or freeze-in. We also measure the primordial amplitude of vector modes, and constrain the baryon-dark matter cross-section: . Finally, we consider sterile Majorana neutrinos as a dark matter candidate.
基金Supported by the National Natural Science Foundation of China
文摘The GeV-TeV -γ-ray line signal is the smoking gun signature of dark matter annihilation or decay. The detection of such a signal is one of the main targets of some space-based telescopes, including Fermi-LAT and the upcoming missions CALET, DAMPE and Gamma-400. An important feature of γ-ray line photons that originate from dark-matter-annihilation is that they are concentrated at the center of the Galaxy. So far, no reliable γ-ray line has been detected by Fermi-LAT, and the upper limits on the cross section of annihilation into ＂y-rays have been reported. We use these upper limits to estimate the ＂maximal＂ number of -y-ray line photons detectable for Fermi- LAT, DAMPE and Gamma-400, and then investigate the spatial distribution of these photons. We show that the center of the distribution will usually be offset from the Galactic center （Sgr A＊） due to the limited statistics. Such a result is almost indepen- dent of models of the dark matter distribution, and will render the reconstruction of the dark matter distribution with the γ-ray line signal very challenging for foreseeable space-based detectors.
文摘Detailed and redundant measurements of dark matter properties have recently become available. To describe the observations we consider scalar, vector and sterile neutrino dark matter models. A model with vector dark matter is consistent with all current observations.
文摘We compare the observed galaxy stellar mass distributions in the redshift range <img src="Edit_bc01f6dd-d7f9-42f9-9db0-dbd1148de50e.png" alt="" />with expectations of the cold ΛCDM and warm ΛWDM dark matter models, and obtain the warm dark matter cut-off wavenumber: <img src="Edit_ab3d491d-7145-4d59-b4b1-bea473d62333.png" alt="" />. This result is in agreement with the independent measurements with spiral galaxy rotation curves, confirms that <em>k</em><sub>fs</sub> is due to warm dark matter free-streaming, and is consistent with the scenario of dark matter with no freeze-in and no freeze-out. Detailed properties of warm dark matter can be derived from <em>k</em><sub>fs</sub>. The data disfavors the ΛCDM model.
基金supported by the National Key Research and Development Program of China(No.2017YFA0402203),the National Natural Science Foundation of China(Nos.11975159 and 11975162).
文摘Compton scattering with bound electrons contributes to a significant atomic effect in low-momentum transfer,yielding background structures in direct light dark matter searches as well as low-energy rare event experiments.We report the measurement of Compton scattering in low-momentum transfer by implementing a 10-g germanium detector bombarded by a^(137)Cs source with a radioactivity of 8.7 mCi and a scatter photon captured by a cylindrical NaI(Tl)detector.A fully relativistic impulse approximation combined with multi-configuration Dirac–Fock wavefunctions was evaluated,and the scattering function of Geant4 software was replaced by our calculation results.Our measurements show that the Livermore model with the modified scattering function in Geant4 is in good agreement with the experimental data.It is also revealed that atomic many-body effects significantly influence Compton scattering for low-momentum transfer(sub-keV energy transfer).
