Interacting warm dark matter

There are not necessarily dark matter and dark energy in the solar system, and dark energy cannot distribute uniformly in the whole space. Based on Dirac negative energy, Einstein mass-energy relation and principle of equivalence, we proposed the negative matter as the simplest model of unified dark matter and dark energy. All theories are known, only mass includes positive and negative. Because there is repulsion between positive matter and negative matter, so which is invisible dark matter, and repulsion as dark energy. It may explain many phenomena of dark matter and dark energy. We derive that the rotational velocity of galaxy is approximate constant, and an evolutional ratio between total matter and usual matter from 1 to present 11.82 or 7.88. We calculate the accelerated expansion at 9.760 billion years. Further, the mechanism of inflation is origin of positive-negative matters created from nothing, whose expansion is exponential due to strong interactions at small microscopic scales. We propose specifically some possible ways on observe dark matter in the Milky Way. Many observatories should be able to observe these results. Final, we research some basic problems in cosmology: Possible mechanism of missing antimatter, the origins of mass and charge, etc. The negative matter as a candidate of unified dark matter and dark energy is not only the simplest, and is calculable, observable and testable, and may be changed and developed.

Cosmological constraints of interacting phantom dark energy models

We investigate models of interacting dark matter and dark energy for the\nuniverse in a spatially flat Friedmann-Robertson-Walker (FRW) space-time. We\nfind the "source equation" for the total energy density and determine the\nenergy density of each dark component. We introduce an effective one-fluid\ndescription to evidence that interacting and unified models are related with\neach other, analyze the effective model and obtain the attractor solutions. We\nstudy linear and nonlinear interactions, the former comprises a linear\ncombination of the dark matter and dark energy densities, their first\nderivatives, the total energy density, its first and second derivatives and a\nfunction of the scale factor. The latter is a possible generalization of the\nlinear interaction consisting of an aggregate of the above linear combination\nand a significant nonlinear term built with a rational function of the dark\nmatter and dark energy densities homogeneous of degree one. We solve the\nevolution equations of the dark components for both interactions and examine\nexhaustively several examples. There exist cases where the effective one-fluid\ndescription produces different alternatives to the $\\La$CDM model and cases\nwhere the problem of coincidence is alleviated. In addition, we find that some\nnonlinear interactions yield an effective one-fluid model with a Chaplygin gas\nequation of state, whereas others generate cosmological models with de Sitter\nand power-law expansions. We show that a generic nonlinear interaction induces\nan effective equation of state which depends on the scale factor in the same\nway that the variable modified Chaplygin gas model, giving rise to the "relaxed\nChaplygin gas model".\n

In this paper, we investigate a new phenomenological parametrization for unified dark matter and dark energy based on the polynomial expansion of the barotropic equation of state parameter $w$. Our parametrization provides a well-behaving evolution of $w$ for both small and big redshifts as well as in the far future. The dark fluid described by our parametrization behaves for big redshifts like dark matter (DM). Therefore, one can parametrize dark energy and dark matter using a single dark fluid, like in the case of the Chaplygin gas. Within this parametrization, we consider two models: one with a dark energy (DE) barotropic parameter fixed to be $\ensuremath{-}1$ and the second one, where $w\ensuremath{\ne}\ensuremath{-}1$ is chosen to match the best fit to the data. We study the main cosmological properties of these models at the expansion and perturbation levels. Based on the Markov chain Monte Carlo method with the currently available cosmic observational data sets, we constrain these models to determine the cosmological parameters at the level of the background and clustering of matter. We consider the interaction between dark matter and dark energy which directly affects the evolution of matter and its clustering. Our model appears to be perfectly consistent with the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model, while providing unification of DE and DM.

In this paper, after reconstructing the redshift evolution of the Hubble function by adopting Gaussian process techniques, we estimate the best-fit parameters for some flat Friedmann cosmological models based on a modified Chaplygin gas interacting with dark matter. In fact, the expansion history of the Universe will be investigated because passively evolving galaxies constitute cosmic chronometers. An estimate for the present-day values of the deceleration parameter, adiabatic speed of sound within the dark energy fluid, effective dark energy, and dark matter equation of state parameters is provided. By this, we mean that the interaction term between the two dark fluids, which breaks the Bianchi symmetries, will be interpreted as an effective contribution to the dark matter pressure similarly to the framework of the “Generalized Dark Matter”. We investigate whether the estimates of the Hubble constant and of the present-day abundance of dark matter are sensitive to the dark matter–dark energy coupling. We will also show that the cosmic chronometers data favor a cold dark matter, and that our findings are in agreement with the Le Châtelier–Braun principle according to which dark energy should decay into dark matter.

The EDGES experiment has observed an excess trough ($-500^{+200}_{-500}$ mK) in the brightness temperature $T_{21}$ of the 21cm absorption line of neutral Hydrogen atom (HI) from the era of cosmic dawn ($z \simeq 17.2$). We consider possible interaction of Dark Matter and Dark Energy fluid along with the cooling off of the baryon matter by its collision with Dark Matter to explain the observed excess trough of $T_{21}$. We make use of three different Dark Matter-Dark Energy (DM-DE) interaction models to taste the viability of those models in explaining the EDGES results. The evolution of Hubble parameter is modified by DM-DE interactions and this is also addressed in this work. This in turn influences the optical depth of HI 21cm as well as the baryon temperature and thus effects the $T_{21}$ brightness temperature. In addition we also find that the DM-DE interaction enables us to explore Dark Matter with varied mass regimes and their viabilities in terms of satisfying the EDGES result.

We study quintessence cosmology with an effective Λ-term in Lyra manifold. We consider three different models by choosing variable Λ depending on time, the Hubble parameter and the energy density of dark matter and dark energy. Dark energy is assumed as quintessence which interacts with the dark matter. Using numerical analysis we investigate the behavior of cosmological parameters in three different models and compare our results with observational data. State-finder diagnostic is also performed for all models.

We employ the Planck 2013 CMB temperature anisotropy and lensing data, and baryon acoustic oscillation (BAO) data to constrain a phenomenological wCDM model, where dark matter and dark energy interact. We assume time-dependent equation of state parameter for dark energy, and treat dark matter and dark energy as fluids whose energy-exchange rate is proportional to the dark-matter density. The CMB data alone leave a strong degeneracy between the interaction rate and the physical CDM density parameter today, ωc, allowing a large interaction rate |Γ| ∼ H0. However, as has been known for a while, the BAO data break this degeneracy. Moreover, we exploit the CMB lensing potential likelihood, which probes the matter perturbations at redshift z ∼ 2 and is very sensitive to the growth of structure, and hence one of the tools for discerning between the ΛCDM model and its alternatives. However, we find that in the non-phantom models (wde>−1), the constraints remain unchanged by the inclusion of the lensing data and consistent with zero interaction, −0.14 < Γ/H0 < 0.02 at 95% CL. On the contrary, in the phantom models (wde<−1), energy transfer from dark energy to dark matter is moderately favoured over the non-interacting model; 0−0.57 < Γ/H0 < −0.1 at 95% CL with CMB+BAO, while addition of the lensing data shifts this to −0.46 < Γ/H0 < −0.01.

In the very last years, cosmological models where the properties of the dark components of the Universe — dark matter and dark energy — are accounted for by a single ``dark fluid'' have drawn increasing attention and interest. Amongst many proposals, Unified Dark Matter (UDM) cosmologies are promising candidates as effective theories. In these models, a scalar field with a non-canonical kinetic term in its Lagrangian mimics both the accelerated expansion of the Universe at late times and the clustering properties of the large-scale structure of the cosmos. However, UDM models also present peculiar behaviours, the most interesting one being the fact that the perturbations in the dark-matter component of the scalar field do have a non-negligible speed of sound. This gives rise to an effective Jeans scale for the Newtonian potential, below which the dark fluid does not cluster any more. This implies a growth of structures fairly different from that of the concordance ΛCDM model. In this paper, we demonstrate that forthcoming large-scale surveys will be able to discriminate between viable UDM models and ΛCDM to a good degree of accuracy. To this purpose, the planned Euclid satellite will be a powerful tool, since it will provide very accurate data on galaxy clustering and the weak lensing effect of cosmic shear. Finally, we also exploit the constraining power of the ongoing CMB Planck experiment. Although our approach is the most conservative, with the inclusion of only well-understood, linear dynamics, in the end we also show what could be done if some amount of non-linear information were included.

The present paper is basically a synthesis resulting from incorporating Kerr spinning black hole geometry into E-infinity topology, then letting the result bares on the vacuum zero point Casimir effect as well as the cosmic dark energy and dark matter density. In E-infinity theory a quantum particle is represented by a Hausdorff dimension Φ where Φ =2/(√5+1) . The quantum wave on the other hand is represented by Φ2 . To be wave and a particle simultaneously intersection theory leads us to (Φ) (Φ)2= Φ3 which will be shown here to be twice the value of the famous Casimir force of the vacuum for a massless scalar field. Thus in the present work a basically topological interpretation of the Casimir effect is given as a natural intrinsic property of the geometrical topological structure of the quantum-Cantorian micro spacetime. This new interpretation compliments the earlier conventional interpretation as vacuum fluctuation or as a Schwinger source and links the Casimir energy to the so called missing dark energy density of the cosmos. From the view point of the present work Casimir pressure is a local effect acting on the Casimir plates constituting the local boundary condition while dark energy is nothing but the global combined effect of infinitely many quantum waves acting on the M&#246bius-like boundary of the holographic boundary of the entire universe. Since this higher dimensional M&#246bius-like boundary is one sided, there is no outside to balance the internal collective Casimir pressure which then manifests itself as the force behind cosmic expansion, that is to say, dark energy. Thus analogous to the exact irrational value of ordinary energy density of spacetime E(O)=(Φ5/2) mc2 we now have P (Casimir) = (Φ3/2)(ch/d2) where c is the speed of light, m is the mass, h is the Planck constant and d is the plate separation. In addition the new emerging geometry combined with the topology of E-infinity theory leads directly to identifying dark matter with the quasi matter of the ergosphere. As a direct consequence of this new insight E=mc2 which can be written as E = E (O) + E (D) where the exact rational approximation is E (O)=mc2/22 is the ordinary energy density of the cosmos and the exact rational approximation E (D)=mc2/(21/22) is the corresponding dark energy which could be subdivided once more albeit truly approximately into E(D)=mc2/(5/22) +mc2/(16/22) where 5 is the Kaluza Klein spacetime dimension, 16 are the bosonic extra dimensions of Heterotic superstrings and 5/22 □ 22% is approximately the density of the dark matter-like energy of the ergosphere of the Kerr geometry. As for the actual design of our nano reactor, this is closely related to branching clusters of polymer, frequently called lattice animals. In other words we will have Casimir spheres instead of Casimir plates and these spheres will be basically nano particles modelling lattice animals. Here D= 4 will be regarded as spacetime dimensionality while D=6 of percolations are the compactified super string dimensions and D=8 is the dimension of a corresponding super space.

We study the degenerates into the candidates for da rk matter and dark energy from ur-Higgs bosons which has appeared as a mother for SM Higgs boson above. It is shown that only about a tenth of them (ur-Higgs) can be transformed to the Higgs boson with corrected mass by γ- irradiation from surroundings, which is in electrow eak interaction with particles. The remainder degenerate into the hybrid molecules of a glueball and pseudo-scalar mesons (candidate of dark matter); and into the quasi-crystals of fullerene c onsists of σ mesons and some ω mesons (candidate of dark energy) which will raise repulsi ve strong force as soon as the (free) fullerenes approach very near each other. Where we regard the developed fullerene as a finite nucleus of the limit of N(p, n) → 0, namely, m(p, n) → 0 in Dirac equation of mean-field theory. And large amount of condensing (latent) heat from (tt_bar)* g as to the liquid (Higgs boson) might be considered as at last transformed to dark energy, b y which the quasi-crystal above would be annealed (or sublimated) to more developed fulleren e. Then the content ratio between matter (atom), dark matter and dark energy is consistent w ith the latest result of WMAP (9 Years). It is interesting that if we choose reciprocal of the fin e structure constant (1/α) as a mass contributing factor (number) of gluon in QGP for matter, the con tent ratio is completely in accordance with WMAP. Also our mass of dark matter (considered at a round 120.611 GeV/c 2 ) seems relevant to the result of Fermi-LAT.

We analyze the behavior of the scalar field as dark energy of the Universe in a static world of galaxies and clusters of galaxies. We find the analytical solutions of evolution equations of the density and velocity perturbations of dark matter and dark energy, which interact only gravitationally, along with the perturbations of metric in a static world with background Minkowski metric. It was shown that quintessential and phantom dark energy in the static world of galaxies and clusters of galaxies is gravitationally stable and can only oscillate by the influence of self-gravity. In the gravitational field of dark matter perturbations, it is able to condense monotonically, but the amplitude of density and velocity perturbations on all scales remains small. It was also illustrated that the “accretion” of phantom dark energy in the region of dark matter overdensities causes formation of dark energy underdensities-the regions with negative amplitude of density perturbations of dark energy.

We study some properties of the dark degeneracy, which is the fact that what we measure in gravitational experiments is the energy momentum tensor of the total dark sector, and any split into components (as in dark matter and dark energy) is arbitrary. In fact, just one dark fluid is necessary to obtain exactly the same cosmological and astrophysical phenomenology as the LCDM model. We work explicitly the first order perturbation theory and show that beyond the linear order the dark degeneracy is preserved under some general assumptions. Then, we construct the dark fluid from a collection of interacting fluids. Finally, we try to break the degeneracy with a general class of couplings to baryonic matter. Nonetheless, we show that these interactions can also be understood in the context of the LCDM model as between dark matter and baryons. For this last investigation we choose two independent parameterizations for the interactions, one inspired in electromagnetism and the other in Chameleon theories. Then, we constrain them with a joint analysis of CMB and Supernovae observational data.

We consider a cosmological model with an interaction between dark matter and dark energy which leaves the background cosmology unaffected and only affects the evolution of the perturbations. This is achieved by introducing a coupling given in terms of the relative velocities of dark matter and dark energy. This interaction has the distinctive feature of appearing predominantly on small scales, where peculiar velocities can become important. We confront the predictions of the model to cosmological observations and find a potential alleviation of the known tension in the amplitude of density perturbations as measured by low redshift galaxy surveys and the Planck data. The model also predicts a shift in the turnover of the matter power spectrum which does not depend on the horizon at equality (fixed by the background cosmology and, thus, unaffected by the perturbations) and is entirely due to the interaction between dark matter and dark energy. A bias in the peculiar velocity between baryons and dark matter is also shown to be a unique feature of this type of interactions in the dark sector.

We propose a unified framework for dark matter and dark energy based on the thermodynamic properties of a degenerate, relativistic Fermi gas in a higher-dimensional space-time. Extending the standard equation of state to D -dimensional space-time, we derive analytical expressions for the energy density, pressure, number density, sound velocity, and polytropic indices of a zero-temperature Fermi gas. Remarkably, we show that in the limit of vanishing Fermi momentum, the system exhibits a negative vacuum pressure and positive energy density when $$D=(5+4n)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>D</mml:mi> <mml:mo>=</mml:mo> <mml:mo>(</mml:mo> <mml:mn>5</mml:mn> <mml:mo>+</mml:mo> <mml:mn>4</mml:mn> <mml:mi>n</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> , with $$n\in \mathbb {N}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>n</mml:mi> <mml:mo>∈</mml:mo> <mml:mi>N</mml:mi> </mml:mrow> </mml:math> . This feature provides a natural mechanism for the emergence of a cosmological constant-like component from fermionic matter in extra dimensions. In this context, dark matter arises from the bulk fermions’ rest mass energy, while dark energy emerges from their vacuum contributions. The observed cosmological vacuum energy density can be matched by fixing the compactification length scale, leading to constraints that depend on the fermion mass and the number of extra dimensions. Our results suggest that the dark sector may originate from a common fermionic source embedded in a higher-dimensional space-time, offering a novel pathway toward the unification of dark matter and dark energy.