The EDGES low-band experiment has measured an absorption feature in the cosmic microwave background radiation (CMB), corresponding to the 21 cm hyperfine transition of hydrogen at redshift $z \simeq 17$, before the era of cosmic reionization. The amplitude of this absorption is connected to the ratio of singlet and triplet hyperfine states in the hydrogen gas, which can be parametrized by a spin temperature. The EDGES result suggests that the spin temperature is lower than the expected temperatures of both the CMB and the hydrogen gas. A variety of mechanisms have been proposed in order to explain this signal, for example by lowering the kinetic temperature of the hydrogen gas via dark matter interactions. We introduce an alternative mechanism, by which a sub-GeV dark matter particle with spin-dependent coupling to nucleons or electrons can cause hyperfine transitions and lower the spin temperature directly, with negligible reduction of the kinetic temperature of the hydrogen gas. We consider a model with an asymmetric dark matter fermion and a light pseudo-vector mediator. Significant reduction of the spin temperature by this simple model is excluded, most strongly by coupling constant bounds coming from stellar cooling. Perhaps an alternative dark sector model, subject to different sets of constraints, can lower the spin temperature by the same mechanism.
I review the current status of Big Bang Cosmology, with emphasis on current issues in dark matter, dark energy, and galaxy formation. These topics motivate many of the current goals of experimental cosmology which range from targeting the nature of dark energy and dark matter to probing the epoch of the first stars and galaxies.
The cosmological model of dark energy interacting with cold dark matter without coupling to the baryonic matter, is studied in the background of both classical Einstein and loop quantum cosmology. We consider two types of interacting models. In the former model, the interaction is a linear combination of the densities of two dark sectors, while in the latter model, the interaction with a constant transfer rate depends only on the density of cold dark matter. It is shown that the dynamical results in loop quantum cosmology are different from those in classical Einstein cosmology for both two ki…
We study Einstein's equations with an isotropic but inhomogeneous metric in the cosmic rest frame. The equations are solved perturbatively in the late Universe. The leading plus next-to-leading order results agree with observations without using a cosmological constant or dark matter.
Dark matter has been introduced to explain many independent gravitational effects at different astronomical scales, in galaxies, groups of galaxies, clusters, superclusters and even across the full horizon. This review describes the accumulated astronomical, astrophysical, and cosmological evidence for dark matter. It is written at a non-specialist level and intended for an audience with little or only partial knowledge of astrophysics or cosmology.
This paper is a broad-band review of the current status of non-baryonic dark matter research. I start with a historical overview of the evidences of dark matter existence, then I discuss how dark matter is distributed from small scale to large scale, and I then verge the attention to dark matter nature: dark matter candidates and their detection. I finally discuss some of the limits of the $Λ$CDM model, with particular emphasis on the small scale problems of the paradigm.
We investigate the statistical nature of the dark matter particles produced in bouncing cosmology, especially, the evolution of its thermal fluctuations. By explicitly deriving and solving the equation of motion of super-horizon mode, we fully determine the evolution of thermal perturbation of dark matter in a generic bouncing background. And we also show that the evolution of super-horizon modes is stable and will not ruin the background evolution of a generic bouncing universe till the Planck scale. Given no super-horizon thermal perturbation of dark matter appears in standard inflation scen…
In this paper we review the main theoretical and experimental achievements in the field of Dark Matter from the Cosmological and Astrophysical point of view. We revisit it from the very first surveys of local astrophysical matter, up to the stringent constraints on matter properties, coming from the last release of data on cosmological scales. To bring closer and justify the idea of dark matter, we will go across methods and tools for measuring dark matter characteristics, and in some cases a combination of methods that provide one of the greatest direct proofs for dark matter, such as Bullet …
We present the Dark MaGICC project, which aims to investigate the effect of Dark Energy (DE) modeling on galaxy formation via hydrodynamical cosmological simulations. Dark MaGICC includes four dynamical Dark Energy scenarios with time varying equations of state, one with a self-interacting Ratra-Peebles model. In each scenario we simulate three galaxies with high resolution using smoothed particle hydrodynamics (SPH). The baryonic physics model is the same used in the Making Galaxies in a Cosmological Context (MaGICC) project, and we varied only the background cosmology. We find that the Dark …
The bulk viscosity is introduced to model unified dark matter. The viscous unified model assumes the universe is filled with a single fluid with the bulk viscosity. We review the general framework of the viscous cosmology. The Hubble parameter has a direct connection with the bulk viscosity coefficient. For concrete form of the bulk viscosity, the Hubble parameter which has the scaling relation with the redshift can be obtained. We discuss two viscosity models and the cosmological evolution to which they lead. Using SNe Ia data, the viscosity model can be fitted. We briefly review the fitting …
We study the distribution of intragroup dark matter in small groups of dark matter halos of galaxy-like size in a LCDM cosmology. These groups are identified using a physical criterion and may be an appropriate representation of small galaxy groups. We quantify the amount of intragroup dark matter and characterize its distribution. We find that compact associations of halos, as well as those intermediate and loose groups, have rather flat intragroup dark matter profiles with logarithmic slopes of gamma ~0 and ~-0.2$, respectively. Hence, the intragroup dark matter of these halo systems does no…
Unless some unknown symmetry in Nature prevents or suppresses a non-minimal coupling in the dark sector, the dark energy field may interact with the pressureless component of dark matter. In this paper, we investigate some cosmological consequences of a general model of interacting dark matter-dark energy characterized by a dimensionless parameter $ε$. We derive a coupled scalar field version for this general class of scenarios and carry out a joint statistical analysis involving SNe Ia data ({Legacy} and {Constitution} sets), measurements of baryon acoustic oscillation peak at $z = 0.20$ (2dF…
We investigate the holographic, new agegraphic and ghost dark energy models in the framework of fractal cosmology. We consider a fractal FRW universe filled with the dark energy and dark matter. We obtain the equation of state parameters of the selected dark energy models in the ultraviolet regime and discuss on their implications.
The standard model of cosmology is based on the general theory of relativity and demands more than 95\% of the universe to consist of dark matter and dark energy that has no direct observational evidence till date. The foundation of the concept these dark components are based on a fixed relation between the strength of the gravitational field and the matter density. Alternate models are put forward in past to explain the observations without dark components in the universe. Though they have their own merits and draw backs. In this paper we propose a new cosmological model based on Mach's princ…
We investigate interacting dark energy models in the framework of fractal cosmology. We discuss a fractal FRW universe filled with the dark energy and dark matter which interact with each other. We obtain the equation for the relative density of dark matter and dark energy and the deceleration parameter. This model demonstrates new types of evolution, which are not common to cosmological models with this type of interaction.
These lecture notes aim to provide an introduction to dark matter from the perspective of astrophysics/cosmology. We start with a rapid overview of cosmology, including the evolution of the Universe, its thermal history and structure formation. Then we look at the observational evidence for dark matter, from observations of galaxies, galaxy clusters, the anisotropies in the cosmic microwave background radiation and large scale structure. To detect dark matter we need to know how it's distributed, in particular in the Milky Way, so next we overview relevant results from numerical simulations an…
We study the parameter space of cold dark matter axions in two cosmological scenarios with non-standard thermal histories before Big Bang nucleosynthesis: the Low Temperature Reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmolog…
Higgs vacuum stability has important consequences for cosmology. In particular, we argue that if the Higgs vacuum is metastable, then the dark matter cannot contain a single black hole of mass less than $10^{15}{\rm g}$ in our entire past light cone. In addition to being the destroyer microscopic black holes, it may be possible that Higgs vacuum decay is a source of primordial black holes during inflation.
Composite dark matter is a natural setting for implementing inelastic dark matter - the O(100 keV) mass splitting arises from spin-spin interactions of constituent fermions. In models where the constituents are charged under an axial U(1) gauge symmetry that also couples to the Standard Model quarks, dark matter scatters inelastically off Standard Model nuclei and can explain the DAMA/LIBRA annual modulation signal. This article describes the early Universe cosmology of a minimal implementation of a composite inelastic dark matter model where the dark matter is a meson composed of a light and …
Understanding the space of possible theoretical explanations for the observed cosmic acceleration is a central challenge of modern cosmology. This brief document sketches selected aspects of approaches to this problem, focusing on the possibility that a modification to General Relativity is responsible for acceleration, as presented as a plenary talk at the ICHEP 2012 conference.
We investigate Holographic Dark Energy Correspondence of Interacting Generalized Chaplygin Gas model in the framework of compact Kaluza-Klein cosmology. The evolution of the modified holographic dark energy and the equation of state parameter is obtained here.Using the present observational value of density parameter a stable configuration is formed which accommodates Dark Energy. we note a connection between Dark Energy and Phantom field and have shown that Dark Energy might have evolved from a Phantom state in the past.
Production of massive stable relics in $R^2$-modified gravity is considered. It is shown that the cosmological evolution and kinetics of massive species differs significantly from those in the conventional cosmology. The results are applied to the lightest supersymmetric particles and it is argued that they are viable candidates for the constituents of dark matter, if their mass is about 1000 TeV.
The free parameters of a flat accelerating model without dark energy are constrained by using Supernovae type Ia and observational H(z) data. Instead of the vacuum dominance, the present accelerating stage in this modified Einstein-de Sitter cosmology is a consequence of the gravitationally-induced particle production of cold dark matter. The model present a transition from a decelerating to an accelerating regime at low redshifts, and is also able to harmonize a cold dark matter picture with the latest measurements of the Hubble constant H_0, the Supernovae observations (Constitution sample),…
We investigate the effect of a braneworld expansion era on the relic density of asymmetric dark matter. We find that the enhanced expansion rate in the early universe predicted by the Randall-Sundrum II (RSII) model leads to earlier particle freeze-out and an enhanced relic density. This effect has been observed previously by Okada and Seto (2004) for symmetric dark matter models and here we extend their results to the case of asymmetric dark matter. We also discuss the enhanced asymmetric annihilation rate in the braneworld scenario and its implications for indirect detection experiments.
Anomaly mediation is a popular and well motivated supersymmetry breaking scenario. Different possible detailed realisations of this set-up are studied and actively searched for at colliders. Apart from limits coming from flavour, low energy physics and direct collider searches, these models are usually constrained by the requirement of reproducing the observations on dark matter density in the universe. We reanalyse these bounds and in particular we focus on the dark matter bounds both considering the standard cosmological model and alternative cosmological scenarios. These scenarios do not ch…
Cosmological evolution and particle creation in $R^2$-modified gravity are considered for the case of the dominant decay of the scalaron into a pair of gauge bosons due to conformal anomaly. It is shown that in the process of thermalization superheavy dark matter with the coupling strength typical for the GUT SUSY can be created. Such dark matter would have the proper cosmological density if the particle mass is close to $10^{12}$ GeV.
In Phys. Rev. Lett. 109 (2012) 231301, van den Aarssen et al. attempt to solve all the small-scale structure problems in the cold-dark-matter scenario by introducing interaction between the dark-matter particle and an MeV-mass vector boson. In addition, the latter is coupled to ordinary neutrinos, and the neutrino-vector boson coupling constant 10^{-5} < g_nu < 0.1 is required for that purpose. We show that this dark-matter scenario is subject to restrictive constraints from Big Bang Nucleosynthesis.
We explore the dark matter phenomenology of a weak-scale right-handed neutrino in the context of a Two Higgs Doublet Model. The expected signal at direct detection experiments is different from the usual spin-independent and spin-dependent classification since the scattering with quarks depends on the dark matter spin. The dark matter relic density is set by thermal freeze-out and in the presence of non-standard cosmology, where an Abelian gauge symmetry is key for the dark matter production mechanism. We show that such symmetry allows us to simultaneously address neutrino masses and the flavo…
Rényi holographic dark energy (RHDE) correspondence is discussed in higher dimensional cosmology, namely Kaluza-Klein (KK) cosmology. Both interacting and non-interacting cosmological scenario are considered here. It is found that the non-interacting model naturally leads to the late accelerated universe, unlike the standard Holographic Dark Energy models in 4$D$, which requires interaction to accommodate the late-time acceleration of the universe. The interacting model produces an accelerating universe at late time albeit failing to attain the estimated present value of the deceleration param…
In this paper, we investigate the Noether symmetries of $F(T)$ cosmology involving matter and dark energy. In this model, the dark energy is represented by a canonical scalar field with a potential. Two special cases for dark energy are considered including phantom energy and quintessence. We obtain $F(T)\sim T^{3/4},$ and the scalar potential $V(ϕ)\simϕ^2$ for both models of dark energy and discuss quantum picture of this model. Some astrophysical implications are also discussed.
I consider couplings between the dark energy and dark matter sectors. I describe how the existence of an adiabatic regime, in which the dark energy field instantaneously tracks the minimum of its effective potential, opens the door for a catastrophic instability. This {\it adiabatic instability} tightly constrains a wide class of interacting dark sector models. This talk was presented at, and will appear in the proceedings of the DPF-2009 conference.
In $\rmΛ$CDM cosmology, Dark Matter (DM) and neutrinos are assumed to be non-interacting. However, it is possible to have scenarios, where DM-neutrino interaction may be present, leading to scattering of DM with neutrinos and annihilation of DM into neutrinos. We investigate the viability of such scenarios in the light of cosmological data by making use of the Planck 2018 dataset (high-l TT+TE+EE, low-l TT, low-l EE) and constrain these processes in the light of the same. We also discuss a viable particle DM model where DM-neutrino interaction is present, and map the constraints obtained to th…
We discuss Tsallis holographic dark energy (THDE) model in higher dimension. An interacting dark energy model is proposed with Generalized Chaplygin Gas (GCG) in the framework of Compact Kaluza-Klein gravity. It is shown that a stable configuration can be found in the present epoch which is also compatible with the observed value of the density parameter. It is noted that dark energy (DE) might have evolved from a phantom phase in the past. Nature of dark energy is found to depend on the coupling parameter of the interaction. Classical stability consideration is also found to put an upper boun…
These lectures, presented at TASI 2018, provide a concise introduction to inflation, baryogenesis, and aspects of dark matter not covered by the other lectures. The emphasis for inflation is an intuitive understanding and techniques for constraining inflationary models. For baryogenesis we focus on two examples, leptogenesis and electroweak baryogenesis, with attention to singlet-assisted two-step phase transitions. Concerning dark matter, we review different classes of models distinguished by their mechanisms for obtaining the observed relic density, including thermal freeze-out, asymmetric d…
The viscosity of dark matter in cosmological models may cause an accelerated expansion and when this effect is sufficiently large, it can explain the dark energy. In this work, attributing the origin of viscosity to self-interaction of dark matter, we study the viscous cosmology at small redshift $(0\leq z\leq2.5)$. Assuming the cluster scale to be virialized and by modeling a power law behavior of velocity gradients, we calculate the Hubble expansion rate, $H(z)$ and the deceleration parameter, $q(z)$. We then perform a $χ^{2}$ analysis to estimate the best fit model parameters. By using the …
I briefly outline a new physical interpretation to the average cosmological parameters for an inhomogeneous universe with backreaction. The variance in local geometry and gravitational energy between ideal isotropic observers in bound structures and isotropic observers at the volume average location in voids plays a crucial role. Fits of a model universe to observational data suggest the possibility of a new concordance cosmology, in which dark energy is revealed as a mis-identification of gravitational energy gradients that become important when voids grow at late epochs.
The conventional Friedmann cosmology is known to be in tension with the existence of stable particles having interaction strength typical for supersymmetry and heavier than several TeV. A possible way to save life of such particles may be a modification of the standard cosmological expansion law in such a way that the density of these heavy relics would be significantly reduced. We study particle creation in the Starobinsky inflationary model for different decay channels of the scalaron. It is shown that in the process of thermalization superheavy stable particles with the coupling strength ty…
Mirror dark matter interacting with ordinary matter via photon-mirror photon kinetic mixing can explain the DAMA, CoGeNT and CRESSTII direct detection experiments. This explanation requires kinetic mixing of strength $ε\sim 10^{-9}$. Such kinetic mixing will have important implications for early Universe cosmology. We calculate the additional relativistic energy density at recombination, $δN_{eff} [CMB]$. We also calculate the effects for big bang nucleosynthesis, $δN_{eff} [BBN]$. Current hints that both $δN_{eff} [CMB]$ and $δN_{eff} [BBN]$ are non-zero and positive can be accommodated withi…
We consider Tsallis cosmology as an approach to thermodynamic gravity and derive the bound on the Tsallis parameter to be $β<2$ by using the constraints derived from the formation of the primordial light elements, Helium, Deuterium and Litium, from the observational data from Big Bang Nucleosynthesis (BBN) which allows only a very tiny deviation from General Relativity (GR). Next we consider thermal dark matter (DM) freeze-out mechanism in Tsallis cosmological era and derive bounds on the Tsallis parameter from the observed DM relic abundance to be $1-β< 10^{-5}$.
In this article we present the cosmological equivalence between the relativistic Finsler-Randers cosmology, with dark energy and modified gravity constructions, at the background level. Starting from a small deviation from the quadraticity of the Riemannian geometry, through which the local structure of General Relativity is modified and the curvature theory is extended, we extract the modified Friedmann equation. The corresponding extended Finsler-Randers cosmology is very interesting, and it can mimic dark-energy and modified gravity, describing a large class of scale-factor evolutions, from…
The standard $Λ$CDM model of cosmology is formulated as a simple modified gravity coupled to a single scalar field ("darkon") possessing a non-trivial hidden nonlinear Noether symmetry. The main ingredient in the construction is the use of the formalism of non-Riemannian spacetime volume-elements. The associated Noether conserved current produces stress-energy tensor consisting of two additive parts -- dynamically generated dark energy and dark matter components non-interacting among themselves. Noether symmetry breaking via an additional scalar "darkon" potential introduces naturally an inter…
In this paper we study in detail the phase space of a cosmological system consisting of two coupled fluids, namely a dark energy fluid coupled with a superfluid dark matter fluid. The dark matter fluid is assumed to have a superfluid equation of state, hence it is not pressureless and our aim is to find the impact of this non-trivial equation of state on the phase space of the coupled system. We shall use two theoretical contexts, namely that of classical cosmology and that of loop quantum cosmology. In the classical case, we investigated the existence and stability of fixed points, and as we …
We study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter-domination prior to Big-Bang nucleosynthesis. Matter-domination changes the dark matter relic abundance if it ends via reheating to a temperature below the higgsino thermal freeze-out temperature. We perform a model independent analysis of the higgsino dark matter production in such scenario. We show that light higgsino-type dark matter is possible for reheating temperatures close to 1 GeV. We study the impact of dark matter indirect detection and collider physics in this context. W…
We propose a new framework unifying cold dark matter (CDM) and Modified Newtonian Dynamics (MOND) to solve their respective problems on galactic scales and large scale structure formation. In our framework the dark matter clusters on large scales but not on galactic scales. This environment dependence of the dark matter behaviors is controlled by a vector field, which also produces the MOND effects in galaxies. We find that in this framework only a single mass scale needs to be introduced to produce the phenomena of CDM, MOND and also dark energy.
We generalize the time-variable dark energy scalar field $Φ$ model ($Φ$CDM) to nonflat space. We show that even in the space-curvature-dominated epoch the scalar field solution is a time-dependent fixed point or attractor, with scalar field energy density that grows relative to the energy density in spatial curvature. This is the first example of a physically consistent and complete model of dynamical dark energy in a nonflat geometry.
We study the entropy-corrected version of the holographic dark energy (HDE) model in the framework of modified FRW cosmology. We consider a non-flat universe filled with an interacting viscous entropy-corrected HDE (ECHDE) with dark matter. We also include the case of variable gravitational constant G in our model. We obtain the equation of state and the deceleration parameters of the interacting viscous ECHDE. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the interacting…
We outline the key-steps towards the construction of a physical, fully relativistic cosmology, in which we aim to trace Dark Energy and Dark Matter back to physical properties of space. The influence of inhomogeneities on the effective evolution history of the Universe is encoded in backreaction terms and expressed through spatially averaged geometrical invariants. These are absent and interpreted as missing dark fundamental sources in the standard model. In the inhomogeneous case they can be interpreted as energies of an emerging scalar field (the morphon). These averaged invariants vanish fo…
If the dark matter sector in the universe is composed by metastable particles, galaxies and galaxy clusters are expected to undergo significant secular evolution from high to low redshift. We show that the decay of dark matter, with a lifetime compatible with cosmological constraints, can be at the origin of the observed evolution of the Tully-Fisher relation of disk galaxies and alleviate the problem of the size-evolution of elliptical galaxies, while being consistent with the current observational constraints on the gas fraction of clusters of galaxies.
Recently, in a series of works by Liu and Li (L&L), they claimed that there exists a timing asynchrony of $-25.6\,$ms between the spacecraft attitude and radiometer output timestamps in the original raw WMAP time-ordered data (TOD). L&L reprocessed the WMAP data while the aforementioned timing asynchrony has been corrected, and they obtained an alternative CMB map in which the quadrupole dropped to nearly zero. In the present work, we try to see the implications to dark energy cosmology if L&L are right. While L&L claimed that there is a bug in the WMAP pipeline which leads to significantly di…
The appearance of scalar/moduli fields in the early universe, as motivated by string theory, naturally leads to non-thermal "moduli cosmology". Such cosmology provides a consistent framework where the generation of radiation, baryons, and dark matter can occur while maintaining successful Big Bang Nucleosynthesis and avoiding the cosmological moduli problem. We present a relatively economical construction with moduli cosmology, building on a variety of string-inspired components (e.g. supersymmetry, discrete symmetries, Green-Schwarz anomaly cancellation). We address a range of outstanding pro…
A recent study by Farnes (2018) proposed an alternative cosmological model in which both dark matter and dark energy are replaced with a single fluid of negative mass. This paper presents a critical review of that model. A number of problems and discrepancies with observations are identified. For instance, the predicted shape and density of galactic dark matter halos are incorrect. Also, halos would need to be less massive than the baryonic component otherwise they would become gravitationally unstable. Perhaps the most challenging problem in this theory is the presence of a large-scale versio…
Influenced by the renaissance of general relativity that came to pass in the 1950s, the character of cosmology fundamentally changed in the 1960s as it became a well-established empirical science. Although observations went to dominate its practice, extra-theoretical beliefs and principles reminiscent of methodological debates in the 1950s kept playing an important tacit role in cosmological considerations. Specifically, belief in cosmologies that modeled a "closed universe" based on Machian insights remained influential. The rise of the dark matter problem in the early 1970s serves to illustr…
We derive the MOND cosmology which is uniquely corresponding to the original MOND at galaxy scales via entropic gravity method. It inherits the key merit of MOND, that is, it reduces the baryonic matter and non-baryonic dark matter into baryonic matter only. For the first time we obtain the critical parameter in MOND, i.e., the transition acceleration $a_c$ at cosmological scale. We thus solve the long-standing coincidence problem $a_c\sim cH_{0}$. More interestingly, a term like age-graphic dark energy emerges naturally. In the frame of this MOND cosmology, we only need baryonic matter to des…
The holographic dark energy model is obtained from a cosmological constant generated by generic quantum gravity effects giving a minimum length. By contrast, the usual bound for the energy density to be limited by the formation of a black hole simply gives the Friedmann equation. The scale of the current cosmological constant relative to the inflationary scale is an arbitrary parameter characterizing initial conditions, which however can be fixed by introducing a physical principle during inflation, as a function of the number of e-folds and the inflationary scale.
We search for sterile neutrinos in the holographic dark energy cosmology by using the latest observational data. To perform the analysis, we employ the current cosmological observations, including the cosmic microwave background temperature power spectrum data from the Planck mission, the baryon acoustic oscillation measurements, the type Ia supernova data, the redshift space distortion measurements, the shear data of weak lensing observation, the Planck lensing measurement, and the latest direct measurement of $H_0$ as well. We show that, compared to the $Λ$CDM cosmology, the holographic dark…
Gravitational-wave (GW) radiation from a coalescing compact binary is a standard siren as the luminosity distance of each event can be directly measured from the amplitude of the signal. One possibility to constrain cosmology using the GW siren is to perform statistical inference on a population of binary black hole (BBH) events. In essence, this statistical method can be viewed as follows. We can modify the shape of the distribution of observed BBH events by changing cosmological parameters until it eventually matches the distribution constructed from an astrophysical population model, thereb…
Stable scalars can be copiously produced in the Early Universe even if they have no coupling to other fields. We study production of such scalars during and after (high scale) inflation, and obtain strong constraints on their mass scale. Quantum gravity-induced Planck-suppressed operators make an important impact on the abundance of dark relics. Unless the corresponding Wilson coefficients are very small, they normally lead to overproduction of dark states. In the absence of a quantum gravity theory, such effects are uncontrollable, bringing into question predictivity of many non-thermal dark …
