Brief review of recent advances in understanding dark matter and dark energy

In this work, I shall figure out the general structure of dark fabric matter, and the direct interactions of the celestial objects, ordinary matter, and ordinary energy with dark fabric matter and energy. Dark Fabric matter and energy is a hidden dimension of the parallel universes, visible Universe, galaxies, Atoms, molecules, ordinary matter, celestial objects, stellar systems, and Planetary systems. The Main Structure of Dark fabric matter consists of the Dark matter particles called Fabriton particles, Dark Matter Strings, and Dark Matter Webs. The dark matter particles are named fabriton particles. Fabriton means Fast actively binding reacting in total objects naturally. Fabriton is a good proposed name for dark matter particles to be recognized among subatomic particles. The mystery of Dark matter and the dark energy could be solved here entirely. Einstein and Newton built clear mathematical equations to describe the nature of gravity, after them many other people worked warmly to resolve the reality of gravity, dark matter, and dark energy. Gravity is the ripples, curvatures, gravitational waves, and tunnels that form rapidly in the structure of dark fabric matter and energy when celestial objects and ordinary matter particles pass through it directly.

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle and coupling constant. Because of the expansion behaviour in a Robertson-Walker metric we investigate self-interacting dark matter that is warm in the case of thermal relics. The scaling behaviour of dark matter self-interaction energy density shows that it can be the dominant contribution (only) in the very early universe. Thus its impact on primordial nucleosynthesis is used to restrict the interaction strength, which we find to be at least as strong as the strong interaction. Furthermore we explore dark matter decoupling in a self-interaction dominated universe, which is done for the self-interacting warm dark matter as well as for collisionless cold dark matter in a two component scenario. We find that strong dark matter self-interactions do not contradict super-weak inelastic interactions between self-interacting dark matter and baryonic matter and that the natural scale of collisionless cold dark matter decoupling exceeds the weak scale and depends linearly on the particle mass. Finally structure formation analysis reveals a linear growing solution during self-interaction domination; however, only non-cosmological scales are enhanced.

The paper brings a novel approach to unification of dark matter and dark energy in terms of a cosmic fluid. A model is introduced in which the cosmic fluid speed of sound squared is defined as a function of its equation of state (EoS) parameter. It is shown how logarithmic part of this function results in dynamical regimes previously not observed in cosmic fluid models. It is shown that in a particular dynamical regime the model behaves as a unification of dark matter and phantom dark energy. Further, it is shown that the model may describe dark matter - dark energy unification in which dark energy asymptotically behaves as dark energy with a constant EoS parameter larger than −1. In a specific parameter regime the unified fluid model also reproduces global expansion similar to ΛCDM model with fluid speed of sound vanishing for small scale factor values and being small, or even vanishing, for large scale factor values. Finally, it is shown how the model may be instrumental in describing the cosmic fluid dark matter-dark energy-dark matter unification. Physical constraints on model parameters yielding such transient dark energy behavior are obtained.

mwymwAbstract: This study examines the dynamics of recent findings related to dark matter and dark energy, beginning with an overview of the theoretical concepts. It assesses various potential dark matter entities such as sterile neutrinos and primordial black holes, alongside a hypothesized exotic variant of hydrogen atoms. Different cosmic simulations are explored; THESAN simulations demonstrate the critical role of dark matter in galaxy formation conditions and galaxy stellar masses, while EAGLE simulations show that Maxwellian distributions are still effective for analyzing dark matter dynamics. The concept of dark energy in cosmic acceleration is discussed through the equation of state parameter. Observations from instruments like WMAP and studies of supernovae are explored; findings suggest that phi cold dark matter model (ϕCDM) aligns more closely to current observations compare to traditional lambda cold dark matter model (ΛCDM). Furthermore, the exploration of early dark energy as a potential approach to mitigate the Hubble tension is highlighted, proposing it as a vital factor in reconciling observed discrepancies in cosmic expansion rates.

mwymwAbstract:This study examines the dynamics of recent findings related to dark matter and dark energy, beginning with an overview of the theoretical concepts. It assesses various potential dark matter entities such as sterile neutrinos and primordial black holes, alongside a hypothesized exotic variant of hydrogen atoms. Different cosmic simulations are explored; THESAN simulations demonstrate the critical role of dark matter in galaxy formation conditions and galaxy stellar masses, while EAGLE simulations show that Maxwellian distributions are still effective for analyzing dark matter dynamics. The concept of dark energy in cosmic acceleration is discussed through the equation of state parameter. Observations from instruments like WMAP and studies of supernovae are explored; findings suggest that phi cold dark matter model (ϕCDM) aligns more closely to current observations compare to traditional lambda cold dark matter model (ΛCDM). Furthermore, the exploration of early dark energy as a potential approach to mitigate the Hubble tension is highlighted, proposing it as a vital factor in reconciling observed discrepancies in cosmic expansion rates.

We propose a scenario where dark matter (DM) with a wide mass range from a few keV to PeV can be produced solely from evaporating primordial black holes (PBH), while being consistent with the required free streaming length for structure formation. If DM does not have any other interactions apart from gravity and the universe has a PBH dominated phase at early epoch, then PBH evaporation typically leads to overproduction of DM in this mass range. By incorporating this gravitational DM within a Type-I seesaw scenario with three right handed neutrinos (RHN), we bring the abundance of PBH generated DM within observed limits by late entropy injection due to decay of one of the RHNs, acting as the diluter. The diluter, due to its feeble coupling with the bath particles, gets produced primarily from the PBH evaporation thereby leading to the second stage of early matter domination after the end of PBH dominated era. The other two RHNs contribute to the origin of light neutrino mass and also lead to the observed baryon asymmetry via leptogenesis with contributions from both thermally and PBH generated RHNs. The criteria of DM relic and baryon asymmetry can be satisfied simultaneously if DM mass gets restricted to a ballpark in the MeV-GeV regime with the requirement of resonant leptogenesis for heavier DM mass in order to survive the large entropy dilution at late epochs.

In this thesis I study the effects of different Dark Energy models on galaxy formation via numerical simulations. I investigate systems around and be- low Milky-Way masses and describe the effects of dark energy at galactic and sub-galactic scales. Firstly, I analyze high-resolution hydrodynamical simulations of three disc galaxies in dynamical dark energy models. While overall stellar feedback remains the driving mechanisms in shaping galaxies, the effect of the dark energy parametrization plays a larger role than pre- viously thought. Secondly, I broaden the galaxy sample by simulating a 80 Mpc/h side cube of our universe using the same dynamical dark energy mod- els. I show that resolution is a crucial ingredient so that baryonic feedback mechanisms can enhance differences between cosmological models. Thirdly, I investigate the effects of dynamical dark energy on dwarf mass scales. I find that there is more variation from object to object (due to the stochasticity of star formation at these scales) than between the same object in different cosmological models, which makes it hard for observations to disentangle different dark energy scenarios. In the second part of this thesis I investi- gate the effects of coupled dark energy models on galactic and sub-galactic scales via dark matter only high-resolution simulations. I find that coupled models decrease concentrations of (Milky-Way-like) parent haloes and also reduce the number of subhaloes orbiting around them. This improves the agreement with observations and, hence, makes these cosmologies attractive alternatives to a cosmological constant.

The Generalization of the Periodic Table: The 'Periodic Table' of 'Dark Matter'

The evaporation of primordial black holes (PBH) with masses ranging from ~ 10-1 to ~ 109 g could have generated the whole observed dark matter (DM) relic density. It is typically assumed that after being produced, its abundance freezes and remains constant. However, thermalization and number-changing processes in the dark sector can have a strong impact, in particular enhancing the DM population by several orders of magnitude. Here we estimate the boost from general arguments such as the conservation of energy and entropy, independently from the underlying particle physics details of the dark sector. Two main consequences can be highlighted: i) As the DM abundance is increased, a smaller initial energy density of PBHs is required. ii) Thermalization in the dark sector decreases the mean DM kinetic energy, relaxing the bound from structure formation and hence, allowing light DM with mass in the keV ballpark.

Dark energy and dark matter, two subjects of basic physics, have received a lot of attention in the 21st century. From the observational point of view, the interaction between dark energy and dark matter can significantly affect cosmological distances. This gives rise to the possibility of indirectly detecting such interaction through high-redshift cosmological probes. Theoretically, the introduction of interaction between dark energy and dark matter can assist in alleviating the coincidence problem of the standard cosmological model ($\Lambda$CDM model). Furthermore, this can provide a new method of studying the properties of dark matter particles. In this paper, based on the latest observations of multiple measurements of quasars (X-ray+UV quasars acting as standard candles, compact radio quasars acting as standard rulers) covering the redshift range of $0.04~<~z~<~5.1$ and baryonic acoustic oscillation between ($0.38~<~z~<~2.34$), we investigate the observational constraints on a variety of interacting dark energy models ($\gamma_d~$IDE model, $\gamma_m~$IDE model) and other cosmological models ($\Lambda$CDM model, XCDM model). The results provide us with a quantitative analysis of the possible interaction between dark energy and dark matter, as well as the possible range of the mass of dark matter particles. The joint analysis shows that: (1) Multiple measurements of quasars can provide more stringent constraints on the interacting dark energy models, which can further strengthen the potential of quasars acting as effective cosmological standard probes at higher redshifts; (2) In the framework of both $\gamma_m$IDE model and $\gamma_d$IDE model, the quasar data supports possible conversion of dark energy into dark matter at high redshift, which alleviates the coincidence problem to some extent. We also found that the interaction term is of a small value, which demonstrates the negligible interaction between dark matter and dark energy; (3) In the framework of $\Lambda$CDM model, which has shown the best consistency with quasar data, the density parameter of matter in the Universe is constrained at $\Omega_~m=0.317^{+0.007}_{-0.007}$, with the best-fit Hubble constant $H_0=68.177^{+0.497}_{-0.505}$ at 68.3% confidence level. These findings are consistent with the recent microwave background radiation (CMB) measurements from the Planck satellite; (4) If dark matter in the Universe exists in the form of scalar-field dark matter with $Z_2$ symmetry, we obtain the range of the mass of dark matter particles as $56~{\rm~GeV}\lesssim~m_S\lesssim~63~{\rm~GeV}$ or $m_S\gtrsim450~{\rm~GeV}$, based on the dark energy-dark matter coupling term from multiple measurements of quasars. Such conclusions agree well with the latest experimental results aimed at the direct detection of dark matter particles.

Super interacting dark sector: An improvement on self-interacting dark matter via scaling relations of galaxy clusters

In the post-LIGO era, there has been a lot of focus on primordial black holes (PBHs) heavier than ∼ 1015g as potential dark matter (DM) candidates. We point out that the branch of the PBH family that disappeared — PBHs lighter than ∼ 109g that ostensibly Hawking evaporated away in the early Universe — also constitute an interesting frontier for DM physics. Hawking evaporation itself serves as a portal through which such PBHs can illuminate new physics, for example by emitting dark sector particles. Taking a simple DM scalar singlet model as a template, we compute the abundance and mass of PBHs that could have provided, by Hawking evaporation, the correct DM relic density. We consider two classes of such PBHs: those originating from curvature perturbations generated by inflation, and those originating from false vacuum collapse during a first-order phase transition. For PBHs of both origins we compute the gravitational wave (GW) signals emanating from their formation stage: from second-order effects in the case of curvature perturbations, and from sound waves in the case of phase transitions. The GW signals have peak frequencies in the MHz-GHz range typical of such light PBHs. We compute the strength of such GWs compatible with the observed DM relic density, and find that the GW signal morphology can in principle allow one to distinguish between the two PBH formation histories.

The recent interpretation of cold dark matter as the sum of contributions of different mass Primordial Black Hole (PBH) families [1] could explain a number of so far unsolved astrophysical mysteries. Here I assume a realistic 10−8–1010 M⊙ PBH mass distribution providing the bulk of the dark matter, consistent with all observational constraints. I estimate the contribution of baryon accretion onto this PBH population to various cosmic background radiations, concentrating first on the cross-correlation signal between the Cosmic X-ray and the Cosmic infrared background fluctuations discovered in deep Chandra and Spitzer surveys. I assume Bondi capture and advection dominated disk accretion with reasonable parameters like baryon density and effective relative velocity between baryons and PBH, as well as appropriate accretion and radiation efficiencies, and integrate these over the PBH mass spectrum and cosmic time. The prediction of the PBH contribution to the X-ray background is indeed consistent with the residual X-ray background signal and the X-ray/infrared fluctuations. The predicted flux peaks at redshifts z≈17–30, consistent with other constraints requiring the signal to come from such high redshifts. The PBH contribution to the 2–5 μm cosmic infrared background fluctuations is only about 1%, so that these likely come from star formation processes in regions associated with the PBH. I discuss a number of other phenomena, which could be significantly affected by the PBH accretion. Magnetic fields are an essential ingredient in the Bondi capture process, and I argue that the PBH can play an important role in amplifying magnetic seed fields in the early universe and maintaining them until the galactic dynamo processes set in. Next I study the contribution of the assumed PBH population to the re-ionization history of the universe and find that they do not conflict with the stringent ionization limits set by the most recent Planck measurements. X-ray heating from the PBH population can provide a contribution to the entropy floor observed in groups of galaxies. The tantalizing redshifted 21-cm absorption line feature observed by EDGES could well be connected to the radio emission contributed by PBH to the cosmic background radiation. Finally, the number of intermediate-mass black holes and the diffuse X-ray emission in the Galactic Center region are not violated by the assumed PBH dark matter, on the contrary, some of the discrete sources resolved in the deepest {\\em Chandra} observations of the Galactic Ridge could indeed be accreting PBH.

We study a modified interacting dark energy (MIDE) model as a candidate to describe possible interaction between dark energy and dark matter as well as that between dark energy and baryonic matter. More specifically, we introduce a new parameter γ b to quantify the extent of interaction between dark energy and baryons. With three classes of cosmological distance observations including CMB measurements from Planck and WMAP9 results, as well as the recent direct measurements of the Hubble parameter as a function of redshift, we study the allowable values of γ c and γ b and other cosmological parameters. The constraint results obtained by using the MCMC method show: (1) The interaction term γ b quantifying the extent of interaction between baryonic matter and dark energy is nearly equal to 0, which strongly support the whole coupled dark energy scenario based on the assumption that baryons should remain uncoupled in order to allow a non-negligible coupling to dark matter. (2) At the 95.4 % confidence level, we see the energy of dark energy is slightly transferring to that of dark matter; (3) Concerning the typical value of the present energy density ratio between baryonic matter and dark matter in the universe, we obtain a positive coupling between dark energy and matter at 2σ, which indicates that dark energy is leaking energy to matter. Finally, concerning the observational density parameter ratio Ω b /Ω m derived from the gas mass fraction data (f g a s ), within the framework of the phenomenological interaction model, we observe a good compatibility between the observational constraints from f g a s and other combined data.

We have considered a cosmological model of holographic dark energy interacting with dark matter and another unknown component of dark energy of the universe. We have assumed two interaction terms Q and Q′ in order to include the scenario in which the mutual interaction between the two principal components (i.e., holographic dark energy and dark matter) of the universe leads to some loss in other forms of cosmic constituents. Our model is valid for any sign of Q and Q′. If Q<Q′, then part of the dark energy density decays into dark matter and the rest in the other unknown energy density component. But if Q>Q′, then dark matter energy receives from dark energy and from the unknown component of dark energy. Observation suggests that dark energy decays into dark matter. Here we have presented a general prescription of a cosmological model of dark energy which imposes mutual interaction between holographic dark energy, dark matter and another fluid. We have obtained the equation of state for the holographic dark energy density which is interacting with dark matter and other unknown component of dark energy. Using first law of thermodynamics, we have obtained the entropies for holographic dark energy, dark matter and other component of dark energy, when holographic dark energy interacting with two fluids (i.e., dark matter and other component of dark energy). Also we have found the entropy at the horizon when the radius (L) of the event horizon measured on the sphere of the horizon. We have investigated the GSL of thermodynamics at the present time for the universe enveloped by this horizon. Finally, it has been obtained validity of GSL which implies some bounds on deceleration parameter q.