Kind Of Dark Matter Research Articles

Constraining dark photon parameters based on the very high energy observations of blazars

Dark photon is a new gauge boson beyond the Standard Model as a kind of dark matter (DM) candidate. Dark photon dark matter (DPDM) interacts with electromagnetic fields via kinetic mixing, implicating an approach to give a constraint with extragalactic very high energy (VHE) sources. In this work, we attempt to constrain the kinetic mixing from the photon-dark photon scattering process in the host galaxy of blazar, the intergalactic medium and the Milky Way. The VHE photons from a blazar would pass through a dense DM spike around the supermassive black hole where the absorption from DPDM is dramatically enhanced. The kinetic mixing is constrained to be ϵ∼10-7\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon \\sim 10^{-7}$$\\end{document} at a 95%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} confidence level with mD∼0.03-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$m_\ extrm{D}\\sim 0.03 {-} 1$$\\end{document} eV mass range from the observations of Markarian (Mrk) 421 and Mrk 501.

Galaxy Rotation Curve Fitting Using Machine Learning Tools

Galaxy rotation curve (RC) fitting is an important technique which allows the placement of constraints on different kinds of dark matter (DM) halo models. In the case of non-phenomenological DM profiles with no analytic expressions, the art of finding RC best-fits including the full baryonic + DM free parameters can be difficult and time-consuming. In the present work, we use a gradient descent method used in the backpropagation process of training a neural network, to fit the so-called Grand Rotation Curve of the Milky Way (MW) ranging from ∼1 pc all the way to ∼105 pc. We model the mass distribution of our Galaxy including a bulge (inner + main), a disk, and a fermionic dark matter (DM) halo known as the Ruffini-Argüelles-Rueda (RAR) model. This is a semi-analytical model built from first-principle physics such as (quantum) statistical mechanics and thermodynamics, whose more general density profile has a dense core–diluted halo morphology with no analytic expression. As shown recently and further verified here, the dark and compact fermion-core can work as an alternative to the central black hole in SgrA* when including data at milliparsec scales from the S-cluster stars. Thus, we show the ability of this state-of-the-art machine learning tool in providing the best-fit parameters to the overall MW RC in the 10−2–105 pc range, in a few hours of CPU time.

Discovery prospects for heavy dark matter in KAGRA

We discuss the discovery prospects for kg-scale dark matter with a Yukawa-like long-range interaction in Kamioka Gravitational Wave Detector (KAGRA). We consider the interaction range to be in the order of kilometers, thus the dark matter may interact with multiple KAGRA mirrors simultaneously. The induced signal strain is in many cases dominated by frequencies below about 130 Hz. Due to the geometry of the detector there is some strong directional sensitivity. It turns out that KAGRA would be able to constrain such kind of dark matter within a few years of operation. With our set of assumptions we expect that KAGRA could detect a few events per year for 10 kg dark matter, with a Yukawa interaction with a range of 10 km and an effective coupling constant around $10^6$.

Distinguishing two dark matter component particles at e+e− colliders

We investigate ways of identifying two kinds of dark matter (DM) component particles at high-energy colliders. The strategy is to notice and distinguish double-peaks(humps) in the missing energy/transverse energy distribution. The relative advantage of looking for missing energy is pointed out, in view of the fact that the longitudinal component of the momentum imbalance becomes an added input. It thus turns out that an electron-positron collider is better suited for discovering a two-component DM scenario, so long as both of the components are kinematically accessible. This and a number of associated conclusions are established, using for illustration a scenario including a scalar and a spin-1/2 particle. We also formulate a set of measurable quantities which quantify the distinguishability of the two humps, defined in terms of double-Gaussian fits to the missing energy distribution. The efficacy of these variables in various regions of the parameter space is discussed, using the aforesaid model as illustration.

Polytropic spheres modelling dark matter haloes of dwarf galaxies

Context. Dwarf galaxies and their dark matter (DM) haloes have velocity curves of a different character than those in large galaxies. These velocity curves are modelled by a simple pseudo-isothermal model containing only two parameters, which do not give us insight into the physics of the DM halo. Aims. We seek to obtain some insight into the physical conditions in DM haloes of dwarf galaxies by using a simple physically based model of DM haloes. Methods. To treat the diversity of the dwarf galaxy velocity profiles in a unifying framework, we applied polytropic spheres characterised by the polytropic index n and the relativistic parameter σ as a model of dwarf-galaxy DM haloes and matched the velocity of circular geodesics of the polytropes to the velocity curves observed in the dwarf galaxies from the LITTLE THINGS ensemble. Results. We introduce three classes of the LITTLE THINGS dwarf galaxies in relation to the polytrope models due to the different character of the velocity profile. The first class corresponds to polytropes that have n < 1 with linearly increasing velocity along the whole profile, the second class has 1 < n < 2 and the velocity profile becomes flat in the external region, the third class has n > 2, and the velocity profile reaches a maximum and demonstrates a decline in the external region. The σ parameter has to be strongly non-relativistic (σ < 10−8) for all dwarf galaxy models; this parameter varies for the models of each class, but these variations have negligible influence on the character of the velocity profile. Conclusions. Our results indicate a possibility that at least two different kinds of DM are behind the composition of DM haloes. The matches of the observational velocity curves are of the same quality as those obtained by the pseudo-isothermal, core-like models of dwarf galaxy DM haloes.

The Breakthrough Listen Search for Intelligent Life: Public Data, Formats, Reduction, and Archiving

Breakthrough Listen is the most comprehensive and sensitive search for extraterrestrial intelligence (SETI) to date, employing a collection of international observational facilities including both radio and optical telescopes. During the first three years of the Listen program, thousands of targets have been observed with the Green Bank Telescope (GBT), Parkes Telescope and Automated Planet Finder. At GBT and Parkes, observations have been performed ranging from 700 MHz to 26 GHz, with raw data volumes averaging over 1 PB day−1. A pseudo-real time software spectroscopy suite is used to produce multi-resolution spectrograms amounting to approximately 400 GB h−1 GHz−1 beam−1. For certain targets, raw baseband voltage data is also preserved. Observations with the Automated Planet Finder produce both two-dimensional and one-dimensional high-resolution (R ∼ 105) echelle spectral data. Although the primary purpose of Listen data acquisition is for SETI, a range of secondary science has also been performed with these data, including studies of fast radio bursts. Other current and potential research topics include spectral line studies, searches for certain kinds of dark matter, probes of interstellar scattering, pulsar searches, radio transient searches and investigations of stellar activity. Listen data are also being used in the development of algorithms, including machine-learning approaches to modulation scheme classification and outlier detection, that have wide applicability not just for astronomical research but for a broad range of science and engineering. In this paper, we describe the hardware and software pipeline used for collection, reduction, archival, and public dissemination of Listen data. We describe the data formats and tools, and present Breakthrough Listen Data Release 1.0 (BLDR 1.0), a defined set of publicly available raw and reduced data totaling 1 PB.

Cosmological models with the energy density of random fluctuations and the Hubble-constant problem

First the fluctuation energy is derived from the adiabatic random fluctuations due to the second-order perturbation theory, and the evolutionary relation for it is expressed in the form of rho_f = rho_f (rho), where rho and rho_f are the densities of ordinary dust and the fluctuation energy, respectively. The pressureless matter as a constituent of the universe at the later stage is assumed to consist of ordinary dust and the fluctuation energy. Next, cosmological models including the fluctuation energy as a kind of dark matter are derived using the above relation, and it is found that the Hubble parameter and the other model parameters in the derived models can be consistent with the recent observational values. Moreover, the perturbations of rho and rho_f are studied.

Can a millicharged dark matter particle emit an observable γ-ray line?

If a gamma-ray line is observed in the near future, it will be important to determine what kind of dark matter (DM) particle could be at its origin. We investigate the possibility that the gamma-ray line would be induced by a slow DM particle decay associated to the fact that the DM particle would not be absolutely neutral. A "millicharge" for the DM particle can be induced in various ways, in particular from a kinetic mixing interaction or through the Stueckelberg mechanism. We show that such a scenario could lead in specific cases to an observable gamma-ray line. This possibility can be considered in a systematic model-independent way, by writing down the corresponding effective theory. This allows for a multi-channel analysis, giving in particular upper bounds on the intensity of the associated gamma-ray line from cosmic rays emission. Our analysis includes the possibility that in the two-body decay the photon is accompanied with a neutrino. We show that, given the stringent constraints which hold on the millicharge of the neutrinos, this is not an option, except if the DM particle mass lies in the very light KeV-MeV range, allowing for a possibility of explanation of the recently claimed, yet to be confirmed, ~3.5KeV X-ray line.

Structure formation with scalar field dark matter: the field approach

We study the formation of structure in the Universe assuming that dark matter can be described by a scalar field Φ̃ with a potential V(Φ) = −\U0001d52a2Φ̃2/2+λΦ̃4/4. We derive the evolution equations of the scalar field in the linear regime of perturbations. We investigate the symmetry breaking and possibly a phase transition of this scalar field in the early Universe. At low temperatures, the scalar perturbations have an oscillating growing mode and therefore, this kind of dark matter could lead to the formation of gravitational structures. In order to study the nonlinear regime, we use the spherical collapse model and show that, in the quadratic potential limit, this kind of dark matter can form virialized structures. The main difference with the traditional Cold Dark Matter paradigm is that the formation of structure in the scalar field model can occur at earlier times. Thus, if the dark matter behaves as a scalar field, large galaxies are expected to be formed already at high redshifts.

A brief Review of the Scalar Field Dark Matter model

In the last time the cold dark matter (CDM) model has suggested more and more that it is not able to describe all the properties of nearby galaxies that can be observed in great detail as well as that it has some problems in the mechanism by which matter is more rapidly gathered into large-scale structure such as galaxies and clusters of galaxies. In this work we revisit an alternative model, the scalar field dark matter (SFDM) model, which proposes that the galactic haloes form by condensation of a scalar field (SF) very early in the Universe, i.e., in this model the haloes of galaxies are astronomical Bose-Einstein Condensate drops of SF. On the other hand, large-scale structures like clusters or superclusters of galaxies form similar to the ACDM model, by hierarchy, thus all the predictions of the ACDM model at cosmological scales are reproduced by SFDM. This model predicts that all galaxy haloes must be very similar and exist for higher redshifts than in the ACDM model. In the first part of this review we revisit the cosmological evolution of SFDM model with a scalar potential m2Φ2/2 + λΦ4/4 with two different frameworks: the field and fluid approach. We derive the evolution equations of the SF in the linear regime of perturbations as well. The scalar fluctuations have an oscillating growing mode and therefore, this kind of dark matter could lead to the early formation of gravitational structures in the Universe. We also revisit how BEC dark matter haloes exhibit a natural cut of the mass power spectrum. In the second part, we study the core central density profiles of BEC dark matter haloes and fit high-resolution rotation curves, we show a sample of some low surface brightness galaxies. The mean value of the logarithmic inner density slopes is α = −0.27 ± 0.18. Using a model independent new definition of the core in the BEC density profile, we show that the recent observation of the constant dark matter central surface density can be reproduced. We conclude that in light of the difficulties that the ΛCDM model is currently facing the SFDM model can be a worthy alternative to keep exploring further.

Bi-quaternion form of electromagnetism theory

Appling bi-quaternion,we have generalized the classical electromagnetism theory in the presence of electric charge only to a new electromagnetic-symmetry theory in the presence of both electric and magnetic charges.In the bi-quaternion formulation,the Hamiltonian action and corresponding Lagrangians of a system with both electric and magnetic charges are presented.Then form the action principle the field equations and the equations of motion of particle with electric-magnetic charge in electromagnetic field are derived.By analysis of these equations,it is shown that the new theory is consistent with the usual electromagnetism theory in the case of existing electric charge only,and that the new theory is not only the generalized classical theory,but it is also different from other electromagne-tism theories considering both electric and magnetic charges in principle.The important conclusions form the bi-quaternion theory are obtained,that the field produced by electric(or magnetic) charge does not act on the magnetic(or electric) charge,especially,there is no mutual action between the particle with electric charge and the particle with magnetic charge(monopole).Finally,we discuss three physics problems based on the new bi-quaternion electromagnetism theory:(i) A new explanation of the negative results of the experiments to search monopole is presented,in which the negative results cannot conclude no monopole exists,but may indicate the theory of the experiments need revise.(ii) A hypothesis that the monopole-like matter may be a kind of dark matter is given.(iii) The phenomena of fractional electric charges explain as existing particles with different kinds of electric-magnetic charges.

Dearth of dark matter or massive dark halo? Mass-shape-anisotropy degeneracies revealed by nmagic dynamical models of the elliptical galaxy NGC 3379

Recent results from the Planetary Nebula Spectrograph (PNS) survey have revealed a rapidly falling velocity dispersion profile in the nearby elliptical galaxy NGC 3379, casting doubts on whether this intermediate-luminosity galaxy has the kind of dark matter (DM) halo expected in � cold dark matter (� CDM) cosmology. We present a detailed dynamical study of this galaxy, combining ground based long-slit spectroscopy, integral-field data from the Spectrographic Areal Unit for Research on Optical Nebulae (SAURON) instrument and PNS data reaching to more than seven effective radii. We construct dynamical models with the flexible χ 2 -made-to-measure (χ 2 M2M) particle method implemented in the NMAGIC code. We fit spherical, axisymmetric and some triaxial models to the photometric and combined kinematic data in a sequence of gravitational potentials whose circular velocity curves at large radii vary between a near-Keplerian decline and the nearly flat shapes generated by massive haloes. We find that models with a range of halo masses, anisotropies, shapes and inclinations are good representations of the data. In particular, the data are consistent both with nearisotropic systems dominated by the stellar mass and with models in moderately massive haloes with strongly radially anisotropic outer parts (β 0.8 at 7Re). Formal likelihood limits would exclude (at 1σ ) the model with stars only, as well as halo models with vcirc(7Re) 250 km s −1 . All valid models fitting all the data are dynamically stable over gigayears, including the most anisotropic ones. Overall the kinematic data for NGC 3379 out to 7Re are consistent with a range of mass distributions in this galaxy. NGC 3379 may well have a DM halo as predicted by recent merger ¯

The transparency of the Universe limited by Lyα clouds

AbstractThe brightnesses of supernovae are commonly understood to indicate that cosmological expansion is accelerating due to dark energy. However the entire discussion presumes a perfectly transparent universe because no effects of reddening associated with the interstellar extinction law are seen. We note that with two kinds of dark matter (baryonic and nonbaryonic) strongly dominating the known mass of the universe, it is seriously premature to assume that these dark matter components have not reduced the transmission of the universe for cosmological sources.We show that the long‐known Lyα clouds, if nucleated by the population of baryonic dark matter primordial planetoids indicated by quasar microlensing, would act as spherical lenses and achromatically fade cosmologically distant sources. We attempt to estimate the amount of this cosmological fading, but ultimately the calculation is limited by lack of a satisfactory model for the tenuous outer parts of a primordial planetoid. We also consider the effects of such cosmological fading on the light of quasars. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Observational Physics of Mirror World

Mirror (shadow) particles are required to restore symmetry between left- and right-handed coordinate systems. If mirror world exists, it has been born at the same time as the ordinary world and has the same evolution (in the case of the shadow world - broken mirror symmetry, the evolution and structure of the shadow world does not correspond with the observed world). Mirror world is a kind of dark matter. According to Bahcall (1984) local dark matter has a density approximately equal to the density of observed (ordinary) matter.

Dark matter detectors

A fundamental question of astrophysics and cosmology is the nature of dark matter. Astrophysical observations show clearly the existence of some kind of dark matter, though they cannot yet reveal its nature. Dark matter can consist of baryonic particles, or of other (known or unknown) elementary particles. Baryonic dark matter probably exists in the form of dust, gas, or small stars. Other elementary particles constituting the dark matter can possibly be measured in terrestrial experiments. Possibilities for dark matter particles are neutrinos, axions, and weakly interacting massive particles (WIMPs). While a direct detection of relic neutrinos seems at the moment impossible, there are experiments looking for baryonic dark matter in the form of Massive Compact Halo Objects, and for particle dark matter in the form of axions and WIMPS.

Inhomogeneous big-bang model, revived, and evolution of the light elements in cosmic rays

Abstract Inhomogeneous big-bang model for primordial nucleosynthesis allows higher universal mass density parameter of baryons than the standard homogeneous model does, which is marginally consistent with recent astronomical suggestion that some kind of dark matter is made of baryons. Observation of the enhanced heavy elements in metal weak dwarfs is proposed to test the inhomogeneous model. The studies of radioactive nuclear reactions help predict the theoretical abundances more precisely.

A hydrodynamic approach to cosmology: The mixed dark matter cosmological scenario

We compute the evolution of spatially flat, mixed cold and hot dark matter (``MDM) models containing both baryonic matter and two kinds of dark matter. The mean final Zeldovich-Sunyaev $y$ parameter is estimated to be $\bar y=(5.4\pm 2.7)\times 10^{-7}$, with a rms fluctuation of approximately $\bar{\delta y}=(6.0\pm 3.0)\times 10^{-7}$ on arc minute scales. The rate of galaxy formation peaks at an even later epoch ($z\sim 0.3$) than in the standard ($\Omega=1$, $\sigma_8=0.67$) CDM model ($z\sim 0.5$) and, at a redshift of z=4 is nearly a factor of a hundred lower than for the CDM model with the same value of $\sigma_8$. The model yields a cluster mass function which is about a factor of 4 higher than observed but a cluster-cluster correlation length lower by a factor of 2 than what is observed but both are closer to observations than in the COBE normalized CDM model. The one dimensional pairwise velocity dispersion is $605\pm 8$km/s at $1h^{-1}$ separation, lower than that of the CDM model normalized to COBE, but still significantly higher than observations (Davis \& Peebles 1983). A plausible velocity bias $b_v=0.8\pm 0.1$ on this scale will reduce but not remove the discrepancy. Overall, the model is similar both on large and intermediate scales to the standard CDM model normalized to the same value of $\sigma_8$, but the problem with regard to late formation of galaxies is more severe in this model than in that CDM model. Adding hot dark matter significantly improves the ability of COBE normalized CDM scenario to fit existing observations, but the model is in fact not as good as the CDM model with the same $\sigma_8$ and is still probably unsatisfactory with regard to several critical tests.

On the possibility of Bose-star formation

The relaxation time of a gravitationally bounded cloud of bosons is estimated for the case of a large phase-space density of particles. The axionic mass and self-coupling relaxation time are compatible to the age of the Universe if the escape velocity and the mass in the core region satisfy the relation M < 10 8v e 5 2 φ 10 − 1 4 M ⊙ . In the central part of such a cloud an axionic cosmic matter with luminosity ∼ 10 −2v r 5 2 φ 10 − 1 4 M ⊙/ yr will form. An upper bound on the self-coupling is obtained provided the mass distribution in galaxies is dominated by this kind of dark matter.

Must the disk and halo dark matter be different?

view Abstract Citations (29) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Must the Disk and Halo Dark Matter Be Different? Lake, George Abstract There are two dark matter problems in the Galaxy. In addition to the dark halo known to exist in other galaxies, half of the mass of the disk is unaccounted for. The local density of dark matter in the galactic disk is 10-20 times that of the dark halo. I argue that these need not be two different kinds of dark matter. If the dark halo was initially composed of lumps resembling present-day dwarf galaxies, these lumps behaved like "sinking satellites" and some fraction of them settled into the disk. The required amount of matter took 2-3 Gyr to be dragged into the disk by the action of dynamical friction. Roughly 70%-80% of the local material would be in direct orbits, having velocities very close to the local circular velocity and hence a velocity difference with respect to the Earth of approximately the velocity dispersion of the old disk. However, roughly 20%-30% of such matter would be in retrograde orbits having a relative velocity of nearly 500 km s^-1^. If the disk and halo matter are made of the same material, the disk dark matter will dominate the signal in proposed dark matter detection schemes. Publication: The Astronomical Journal Pub Date: November 1989 DOI: 10.1086/115238 Bibcode: 1989AJ.....98.1554L Keywords: Dark Matter; Disk Galaxies; Galactic Mass; Halos; Milky Way Galaxy; Black Holes (Astronomy); Dwarf Galaxies; Hubble Constant; Astrophysics; GALAXIES: THE GALAXY full text sources ADS |