Modified Gravity (MOG) fits to observed radial acceleration of SPARC galaxies
Publication date: Available online 15 May 2019Source: Physics of the Dark UniverseAuthor(s): M.A. Green, J.W. MoffatAbstractThe equation of motion in the generally covariant modified gravity (MOG) theory leads, for weak gravitational fields and non-relativistic motion, to a modification of Newton’s gravitational acceleration law. In addition to the metric gμν, MOG has a vector field ϕμ that couples with gravitational strength to all baryonic matter. The gravitational coupling strength is determined by the MOG parameter α, while parameter μ is the small effective mass of ϕμ. The MOG acceleration...
Source: Physics of the Dark Universe - May 16, 2019 Category: Physics Source Type: research

Kinematic and statistical inconsistencies of Hořava–Lifshitz cosmology
Publication date: September 2019Source: Physics of the Dark Universe, Volume 25Author(s): Orlando Luongo, Marco Muccino, Hernando QuevedoAbstractWe investigate the validity of a minimal cosmological model derived from the renormalizable Hořava action at low redshift scales by using different cosmological and statistical tests. Assuming pure attractive gravity, i.e., λ>1∕3 in the Hořava action, we compare the Union 2.1 supernova type Ia data with the kinematics following from a model-independent approach. The two approaches, although compatible, lead to explicit cosmographic constraints on the free parameters ...
Source: Physics of the Dark Universe - May 15, 2019 Category: Physics Source Type: research

Simplified equations for gravitational field in the vector theory of gravity and new insights into dark energy
Publication date: Available online 11 May 2019Source: Physics of the Dark UniverseAuthor(s): Anatoly A. SvidzinskyAbstractRecently, a new alternative vector theory of gravity has been proposed which assumes that universe has fixed background Euclidean geometry and gravity is a vector field that alters this geometry (Svidzinsky, 2017). It has been shown that vector gravity passes all available gravitational tests and yields, with no free parameters, the value of cosmological constant in agreement with observations. Here we obtain substantially simplified gravitational field equations of vector gravity which are more suitabl...
Source: Physics of the Dark Universe - May 13, 2019 Category: Physics Source Type: research

Testing scale-dependent perturbations in ΛCDM with future galaxy surveys
Publication date: September 2019Source: Physics of the Dark Universe, Volume 25Author(s): Tomasz Denkiewicz, Vincenzo SalzanoAbstractThe quest for the origin of the present accelerated expansion of the Universe is still open. By means of the present geometrical and dynamical observational data, it is very hard to establish, from a statistical perspective, a clear preference among the vast majority of the proposed models for the dynamical dark energy and/or modified gravity theories alternative with respect to the standard ΛCDM scenario. On the other hand, on scales much smaller than present Hubble scale, there are p...
Source: Physics of the Dark Universe - May 13, 2019 Category: Physics Source Type: research

CMB constraints on dark matter phenomenology via reheating in minimal plateau inflation
Publication date: Available online 8 May 2019Source: Physics of the Dark UniverseAuthor(s): Debaprasad Maity, Pankaj SahaAbstractWe consider the CMB constrains on reheating and dark matter parameter space for a specific plateau type inflationary model. The plateau inflationary models which are currently most favored models from data can be well approximated by a potential of the form V(ϕ)∝ϕn around ϕ=0. This fact makes it possible to study the reheating phase with general inflaton equation of state in a viable cosmological scenario. In addition, following our recent work (Maity and Saha, 2018), we generalize the co...
Source: Physics of the Dark Universe - May 9, 2019 Category: Physics Source Type: research

The growth of the density fluctuations in the scale-invariant vacuum theory
Publication date: Available online 6 May 2019Source: Physics of the Dark UniverseAuthor(s): Andre Maeder, Vesselin G. GueorguievAbstractThe growth of the density fluctuations is considered to be an important cosmological test. In the standard model, for a matter dominated universe, the growth of the density perturbations evolves with redshift z like (11+z)s with s=1. This is not fast enough to form galaxies and to account for the observed present-day inhomogeneities. This problem is usually resolved by assuming that at the recombination epoch the baryons settle down in the potential well of the dark matter previously assem...
Source: Physics of the Dark Universe - May 6, 2019 Category: Physics Source Type: research

Reconstruction of f(R) gravity models from observations
Publication date: Available online 26 April 2019Source: Physics of the Dark UniverseAuthor(s): Seokcheon LeeAbstractWe investigate the method for the reconstruction of f(R) gravity models both from the background evolution observations and from the large scale structure measurements. Due to the lack of the first principles, one needs to rely on the observations to build the f(R) gravity models. We show that the general f(R) models can be specified if the 5% accuracy level large scale structure formation observations will be available in the near future in addition to the well constrained background observations. (Source: P...
Source: Physics of the Dark Universe - April 27, 2019 Category: Physics Source Type: research

Signs of dynamical dark energy in current observations
Publication date: Available online 25 April 2019Source: Physics of the Dark UniverseAuthor(s): Joan Solà Peracaula, Adrià Gómez-Valent, Javier de Cruz PérezAbstractInvestigations on dark energy (DE) are currently inconclusive about its time evolution. Hints of this possibility do however glow now and then in the horizon. Herein we assess the current status of dynamical dark energy (DDE) in the light of a large body of updated SNIa+H(z)+BAO+LSS+CMB observations, using the full Planck 2015 CMB likelihood. The performance of the ΛCDM model (with equation of state w=−1 for Λ) is ...
Source: Physics of the Dark Universe - April 27, 2019 Category: Physics Source Type: research

Broadening frequency range of a ferromagnetic axion haloscope with strongly coupled cavity–magnon polaritons
Publication date: September 2019Source: Physics of the Dark Universe, Volume 25Author(s): Graeme Flower, Jeremy Bourhill, Maxim Goryachev, Michael E. TobarAbstractWith the axion being a prime candidate for dark matter, there has been some recent interest in direct detection through a so called ‘Ferromagnetic haloscope.’ Such devices exploit the coupling between axions and electrons in the form of collective spin excitations of magnetic materials with the readout through a microwave cavity. Here, we present a new, general, theoretical treatment of such experiments in a Hamiltonian formulation for strongly couple...
Source: Physics of the Dark Universe - April 27, 2019 Category: Physics Source Type: research

Relativistic quantum geometry from a 5D geometrical vacuum: Gravitational waves from preinflation
Publication date: Available online 24 April 2019Source: Physics of the Dark UniverseAuthor(s): Mauricio Bellini, José Edgar Madriz Aguilar, M. Montes, P.A. SánchezAbstractIn this work we introduce Relativistic Quantum Geometry (RQG) on a Modern Kaluza–Klein theory by studying the boundary conditions on a extended Einstein–Hilbert action for a 5D vacuum defined on a 5D (background) Riemannian manifold. We introduce a connection which describes a displacement from the background manifold to the extended one, on which the 5D vacuum Einstein equations with cosmological constant included, describes the...
Source: Physics of the Dark Universe - April 25, 2019 Category: Physics Source Type: research

Isocurvature fluctuations in the effective Newton’s constant
We present a new isocurvature mode present in scalar-tensor theories of gravity that corresponds to a regular growing solution in which the energy of the relativistic degrees of freedom and the scalar field that regulates the gravitational strength compensate during the radiation dominated epoch on scales much larger than the Hubble radius. We study this isocurvature mode and its impact on anisotropies of the cosmic microwave background for the simplest scalar-tensor theory, i.e. the extended Jordan-Brans–Dicke gravity, in which the scalar field also drives the acceleration of the Universe. We use Planck data to cons...
Source: Physics of the Dark Universe - April 19, 2019 Category: Physics Source Type: research

Broadening frequency range of a ferromagnetic axion haloscope with strongly coupled cavity-magnon polaritons
Publication date: Available online 19 April 2019Source: Physics of the Dark UniverseAuthor(s): Graeme Flower, Jeremy Bourhill, Maxim Goryachev, Michael E. TobarAbstractWith the axion being a prime candidate for dark matter, there has been some recent interest in direct detection through a so called ‘Ferromagnetic haloscope.’ Such devices exploit the coupling between axions and electrons in the form of collective spin excitations of magnetic materials with the readout through a microwave cavity. Here, we present a new, general, theoretical treatment of such experiments in a Hamiltonian formulation for strongly c...
Source: Physics of the Dark Universe - April 19, 2019 Category: Physics Source Type: research

Consistency of local and astrophysical tests of the stability of fundamental constants
Publication date: Available online 16 April 2019Source: Physics of the Dark UniverseAuthor(s): C.J.A.P. Martins, M. Vila MiñanaAbstractTests of the stability of nature’s fundamental constants are one of the cornerstones of the ongoing search for the new physics which is required to explain the recent acceleration of the universe. The two main settings for these tests are high-resolution spectroscopy of astrophysical systems (mainly in low-density absorption clouds along the line of sight of bright quasars) and laboratory comparisons of pairs of atomic clocks. Here we use standard chi-square techniques to perfo...
Source: Physics of the Dark Universe - April 17, 2019 Category: Physics Source Type: research

Detection of Ultra-High Energy neutrinos skimming the Earth due to decay of superheavy dark matter at JEM-EUSO
Publication date: Available online 11 April 2019Source: Physics of the Dark UniverseAuthor(s): Ye XuAbstractThe possibility of detecting Ultra-high energy (UHE from now on) neutrinos due to superheavy dark matter are considered by the neutrinos interaction with the nuclei in the air in the present paper. To reject other standard model particles, UHE neutrinos, from superheavy dark matter and astrophysical sources, skimming the Earth are detected at JEM-EUSO. Then the numbers of UHE neutrinos detected by JEM-EUSO are evaluated at different energies (1 EeV ¡ E ¡ 1 ZeV) in 5 years. If the energy thresholds are tak...
Source: Physics of the Dark Universe - April 13, 2019 Category: Physics Source Type: research

Cosmic Microwave Background constraints on non-minimal couplings in inflationary models with power law potentials
Publication date: Available online 18 March 2019Source: Physics of the Dark UniverseAuthor(s): Mehdi Shokri, Fabrizio Renzi, Alessandro MelchiorriAbstractInflationary models with power-law potentials are starting to be severely constrained by the recent measurements of Cosmic Microwave Background anisotropies provided by the Planck Satellite and by the BICEP2 telescope. In particular, models with power-law potentials V(φ)∝φn with n≥2 are strongly disfavored by present data since they predict a sizable contribution of gravitational waves with a tensor/scalar ratio of r∼0.15 that is at odds with current l...
Source: Physics of the Dark Universe - March 18, 2019 Category: Physics Source Type: research

The 21 cm absorption line and the axion quark nugget dark matter model
Publication date: Available online 15 March 2019Source: Physics of the Dark UniverseAuthor(s): K. Lawson, A.R. ZhitnitskyAbstractWe argue that dark matter in the form of macroscopically large nuggets of standard model quarks and antiquarks can help to alleviate the tension between standard model cosmology and the recent EDGES observation of a stronger than anticipated 21 cm absorption feature. The effect occurs as a result of the thermal emission from quark nugget dark matter at early times and at energies well below the peak of the CMB. Similar radiation at early times may also contribute a fraction of the GHz range ...
Source: Physics of the Dark Universe - March 16, 2019 Category: Physics Source Type: research

Accelerating the BSM interpretation of LHC data with machine learning
We present here a new machine learning method that accelerates the interpretation of LHC data, by learning the relationship between BSM theory parameters and data. As a proof-of-concept, we demonstrate that this technique accurately predicts natural SUSY signal events in two signal regions at the High Luminosity LHC, up to four orders of magnitude faster than standard techniques. The new approach makes it possible to rapidly and accurately reconstruct the theory parameters of complex BSM theories, should an excess in the data be discovered at the LHC. (Source: Physics of the Dark Universe)
Source: Physics of the Dark Universe - March 15, 2019 Category: Physics Source Type: research

Gravitational collapse of an interacting vacuum energy density with an anisotropic fluid
Publication date: Available online 8 March 2019Source: Physics of the Dark UniverseAuthor(s): Hasrat Hussain Shah, Farook Rahaman, Amna Ali, Sabirudin MollaAbstractWe investigate the effects of anisotropic pressure on the gravitational collapse of spherically symmetric, gravitational bound objects. The concept of a pressure anisotropy in stellar models is produced by a large set of physical phenomena in high density regimes. We consider a gravitational collapse process of the anisotropic fluid interacting with a growing vacuum energy density. We consider the full general-relativistic treatment of this problem and obtain ex...
Source: Physics of the Dark Universe - March 10, 2019 Category: Physics Source Type: research

Axion dark matter and the 21-cm signal
Publication date: Available online 1 March 2019Source: Physics of the Dark UniverseAuthor(s): Pierre SikivieAbstractIt was shown in Erken et al. (2012) that cold dark matter axions reach thermal contact with baryons, and therefore cool them, shortly after the axions thermalize among themselves and form a Bose–Einstein condensate. The recent observation by the EDGES collaboration of a baryon temperature at cosmic dawn lower than expected under “standard” assumptions is interpreted as new evidence that the dark matter is axions, at least in part. Baryon cooling by dark matter axions is found to be cons...
Source: Physics of the Dark Universe - March 5, 2019 Category: Physics Source Type: research

Novel constraints on fermionic dark matter from galactic observables II: Galaxy scaling relations
Publication date: Available online 14 February 2019Source: Physics of the Dark UniverseAuthor(s): C.R. Argüelles, A. Krut, J.A. Rueda, R. RuffiniAbstractWe have recently introduced in paper I an extension of the Ruffini-Argüelles-Rueda (RAR) model for the distribution of DM in galaxies, by including for escape of particle effects. Being built upon self-gravitating fermions at finite temperatures, the RAR solutions develop a characteristic dense quantum core-diluted halo morphology which, for fermion masses in the range mc2≈ 10–345 keV, was shown to provide good fits to the Milky Way rotation curve. We...
Source: Physics of the Dark Universe - February 15, 2019 Category: Physics Source Type: research

Directly search for Ultra-High Energy WIMPs at IceCube
Publication date: Available online 14 February 2019Source: Physics of the Dark UniverseAuthor(s): Ye XuAbstractI study the possibility of directly detecting Ultra-high energy (UHE from now on) WIMPs by the IceCube experiment, via the WIMPs interaction with the nuclei in the ice. I evaluate galactic and extragalactic UHE WIMP and astrophysical and atmospheric neutrino event rates at energy range of 10 TeV - 10 PeV. I assume UHE WIMPs χ are only from the decay of superheavy dark matter ϕ, that is ϕ→χχ̄. If the lifetime of superheavy dark matter τϕ is taken to be 5×1021s, WIMPs can be detected a...
Source: Physics of the Dark Universe - February 15, 2019 Category: Physics Source Type: research

Observational constraints on inflationary potentials within the quantum collapse framework
Publication date: Available online 14 February 2019Source: Physics of the Dark UniverseAuthor(s): Gabriel León, Alejandro Pujol, Susana J. Landau, María Pía PiccirilliAbstractThe physical mechanism responsible for the emergence of primordial cosmic seeds from a perfect isotropic and homogeneous Universe has not been fully addressed in standard cosmic inflation. To handle this shortcoming, D. Sudarsky et al have developed a proposal: the self-induced collapse hypothesis. In this scheme, the objective collapse of the inflaton’s wave function generates the inhomogeneity and anisotropy at all scales....
Source: Physics of the Dark Universe - February 15, 2019 Category: Physics Source Type: research

Conformal invariant gravity coupled to a gauged scalar field and warped spacetimes
Publication date: Available online 6 February 2019Source: Physics of the Dark UniverseAuthor(s): Reinoud Jan SlagterAbstractWe investigate the conformal invariant Lagrangian of the self-gravitating U(1) scalar-gauge field on the time-dependent Bondi-Marder axially symmetric spacetime. By considering the conformal symmetry as exact at the level of the Lagrangian and broken in the vacuum, a consistent model is found with an exact solution of the vacuum Bondi-Marder spacetime, written as gμν=ω2ḡμν, where ω is the conformal factor and ḡμν the ‘un-physical‘ spacetime. Curvature coul...
Source: Physics of the Dark Universe - February 7, 2019 Category: Physics Source Type: research

Large-scales solitonic back-reaction behavior in power-law inflation and its relationship with dark energy
Publication date: Available online 7 February 2019Source: Physics of the Dark UniverseAuthor(s): Juan Ignacio Musmarra, Mariano Anabitarte, Mauricio BelliniAbstractWe study the behavior of large-scale (cosmological) modes of back-reaction effects during inflation. We find that the group of modes which describes the very large-scale fluctuations of energy density during inflation due to back-reaction effects evolve in phase between them, but there is a tear of these modes with respect to the other modes that describe astrophysical scales. This effect could be the origin for the large-scale homogeneity and isotropy of the un...
Source: Physics of the Dark Universe - February 7, 2019 Category: Physics Source Type: research

Axionic extension of the Einstein-aether theory: How does dynamic aether regulate the state of axionic dark matter?
Publication date: Available online 5 February 2019Source: Physics of the Dark UniverseAuthor(s): Alexander B. Balakin, Amir F. ShakirzyanovAbstractIn the framework of axionic extension of the Einstein-aether theory we establish the model, which describes a stiff regulation of the behavior of axionic dark matter by the dynamic aether. The aether realizes this procedure via the modified Higgs potential, designed for modeling of nonlinear self-interaction of pseudoscalar (axion) field; the modification of this potential is that its minima are not fixed, and their positions and depths depend now on the square of the covariant ...
Source: Physics of the Dark Universe - February 6, 2019 Category: Physics Source Type: research

Kinetic inflation in deformed phase space Brans–Dicke cosmology
Publication date: Available online 5 February 2019Source: Physics of the Dark UniverseAuthor(s): S.M.M. Rasouli, J. Marto, P.V. MonizAbstractIn this paper, by establishing a Brans–Dicke (BD) cosmology by means of a deformed phase space, in the absence of any scalar potential, cosmological constant and ordinary matter, we show that it is feasible to overcome obstacles reported in the corresponding commutative (non-deformed) frameworks. More concretely, by applying the Hamiltonian formalism and introducing a dynamical deformation, between the momenta associated to the FLRW scale factor and the BD scalar field, we obtai...
Source: Physics of the Dark Universe - February 5, 2019 Category: Physics Source Type: research

The Umami Chaplygin model
Publication date: Available online 5 February 2019Source: Physics of the Dark UniverseAuthor(s): Ruth Lazkoz, María Ortiz-Baños, Vincenzo SalzanoAbstractIn this work we study a phenomenological generalization of the Chaplygin cosmological model, which we call umami Chaplygin model. We consider three different cosmological background scenarios in which our fluid can play three different roles: only as a dark energy component; as a dark matter and dark energy component; and as a dark plus baryonic matter and dark energy component. With such analysis we explore the possibility to unify the dark fluids into one s...
Source: Physics of the Dark Universe - February 5, 2019 Category: Physics Source Type: research

Interference-assisted resonant detection of axions
Publication date: Available online 30 January 2019Source: Physics of the Dark UniverseAuthor(s): H.B. Tran Tan, V.V. Flambaum, I.B. Samsonov, Y.V. Stadnik, D. BudkerAbstractDetection schemes for the quantum-chromodynamics axions and other axion-like particles in light-shining-through-a-wall (LSW) experiments are based on the conversion of these particles into photons in a magnetic field. An alternative scheme may involve the detection via a resonant atomic or molecular transition induced by resonant axion absorption. The signal obtained in this process is second order in the axion-electron interaction constant but may beco...
Source: Physics of the Dark Universe - January 31, 2019 Category: Physics Source Type: research

New predictions from the logotropic model
Publication date: Available online 30 January 2019Source: Physics of the Dark UniverseAuthor(s): Pierre-Henri ChavanisAbstractIn a previous paper (Chavanis, 2015) we have introduced a new cosmological model that we called the logotropic model. This model involves a fundamental constant Λ which is the counterpart of Einstein’s cosmological constant in the ΛCDM model. The logotropic model is able to account, without free parameter, for the constant surface density of the dark matter halos, for their mass–radius relation, and for the Tully-Fisher relation. In this paper, we explore other consequences...
Source: Physics of the Dark Universe - January 31, 2019 Category: Physics Source Type: research

The role of non-gaussianities in primordial black hole formation
Publication date: Available online 31 January 2019Source: Physics of the Dark UniverseAuthor(s): Vicente Atal, Cristiano GermaniAbstractWe re-analyse current single-field inflationary models related to primordial black holes formation. We do so by taking into account recent developments on the estimations of their abundances and the influence of non-gaussianities. We show that, for all of them, the gaussian approximation, which is typically used to estimate the primordial black holes abundances, fails. However, in the case in which the inflaton potential has an inflection point, the contribution of non-gaussianities is onl...
Source: Physics of the Dark Universe - January 31, 2019 Category: Physics Source Type: research

Milliarcsecond compact structure of radio quasars and the geometry of the Universe
Publication date: Available online 31 January 2019Source: Physics of the Dark UniverseAuthor(s): Shuo Cao, Jingzhao Qi, Marek Biesiada, Xiaogang Zheng, Tengpeng Xu, Yu Pan, Zong-Hong ZhuAbstractIn this paper, by using the recently compiled set of 120 intermediate-luminosity quasars (ILQSO) observed in a single-frequency VLBI survey, we propose an improved model-independent method to probe cosmic curvature parameter Ωk and make the first measurement of the cosmic curvature referring to a distant past, with redshifts up to z∼3.0. Compared with other methods, the proposed one involving the quasar data achieves const...
Source: Physics of the Dark Universe - January 31, 2019 Category: Physics Source Type: research

Circular motion and energy extraction in a rotating black hole
Publication date: Available online 22 January 2019Source: Physics of the Dark UniverseAuthor(s): M. Shahzadi, Z. Yousaf, Saeed Ullah KhanAbstractThis paper explores the circular geodesics of neutral test particles on an equatorial plane around a rotating black hole. After using equations of motion of scalar-tensor-vector gravity with the circular geodesics of null-like particles, we find the equation of photon orbit. With the help of an effective potential form, we have examined the stable regimes of photons orbits. The Lyapunov exponent, as well as the effective force acting on photons, is also investigated. We examine th...
Source: Physics of the Dark Universe - January 23, 2019 Category: Physics Source Type: research

Towards a sound massive cosmology
Publication date: January 2019Source: Physics of the Dark Universe, Volume 23Author(s): Hongsheng Zhang, Ya-peng Hu, Yi ZhangAbstractIt is known that de Rham–Gabadadze–Tolley (dRGT) massive gravity does not permit a homogeneous and isotropic universe with flat or spherical spatial metrics. We demonstrate that a singular reference metric solves this problem in an economic and straightforward way. In the dRGT massive gravity with a singular reference metric, there are sound homogeneous and isotropic cosmological solutions. We investigate cosmologies with the static and dynamical singular reference metrics, respec...
Source: Physics of the Dark Universe - January 11, 2019 Category: Physics Source Type: research

Search for sterile neutrinos in a universe of vacuum energy interacting with cold dark matter
Publication date: Available online 3 January 2019Source: Physics of the Dark UniverseAuthor(s): Lu Feng, Jing-Fei Zhang, Xin ZhangAbstractWe investigate the cosmological constraints on sterile neutrinos in a universe in which vacuum energy interacts with cold dark matter by using latest observational data. We focus on two specific interaction models, Q=βHρv and Q=βHρc. To overcome the problem of large-scale instability in the interacting dark energy scenario, we employ the parametrized post-Friedmann (PPF) approach for interacting dark energy to do the calculation of perturbation evolution. The observatio...
Source: Physics of the Dark Universe - January 4, 2019 Category: Physics Source Type: research

MontePython 3: Boosted MCMC sampler and other features
We present the latest development of the code over the past couple of years. We explain, in particular, two new ingredients both contributing to improve the performance of Metropolis–Hastings sampling: an adaptation algorithm for the jumping factor, and a calculation of the inverse Fisher matrix, which can be used as a proposal density. We present several examples to show that these features speed up convergence and can save many hundreds of CPU-hours in the case of difficult runs, with a poor prior knowledge of the covariance matrix. We also summarise all the functionalities of MontePython in the current release, in...
Source: Physics of the Dark Universe - January 4, 2019 Category: Physics Source Type: research

MadDM v.3.0: A comprehensive tool for dark matter studies
We present MadDM v.3.0, a numerical tool to compute particle dark matter observables in generic new physics models. The new version features a comprehensive and automated framework for dark matter searches at the interface of collider physics, astrophysics and cosmology and is deployed as a plugin of the MadGraph5_aMC@NLO platform, inheriting most of its features. With respect to the previous version, MadDM v.3.0 can now provide predictions for indirect dark matter signatures in astrophysical environments, such as the annihilation cross section at present time and the energy spectra of prompt photons, cosmic rays and neutr...
Source: Physics of the Dark Universe - December 31, 2018 Category: Physics Source Type: research

Hořava–Lifshitz cosmology in light of new data
We present new observational constraints on Lorentz violating Hořava–Lifshitz cosmological scenarios using an updated cosmological data set from Cosmic Microwave Background (Planck CMB), expansion rates of elliptical and lenticular galaxies, JLA compilation (Joint Light-Curve Analysis) data for Type Ia supernovae (SneIa), Baryon Acoustic Oscillations (BAO) and priors on the Hubble parameter with an alternative parameterisation of the equations. Unlike in other approaches we consider the curvature parameter Ωk as a free parameter in the analysis we considered the parameters Ωk and ΔNν as complete...
Source: Physics of the Dark Universe - December 28, 2018 Category: Physics Source Type: research

Quantum cosmology of Eddington-Born–Infeld gravity fed by a scalar field: The big rip case
Publication date: Available online 21 December 2018Source: Physics of the Dark UniverseAuthor(s): Imanol Albarran, Mariam Bouhmadi-López, Che-Yu Chen, Pisin ChenAbstractWe study the quantum avoidance of the big rip singularity in the Eddington-inspired-Born–Infeld (EiBI) phantom model. Instead of considering a simple phantom dark energy component, which is described by a perfect fluid, we consider a more fundamental degree of freedom corresponding to a phantom scalar field with its corresponding potential, which would lead the classical universe to a big rip singularity. We apply a quantum geometrodynamical ap...
Source: Physics of the Dark Universe - December 21, 2018 Category: Physics Source Type: research

Hořava-Lifshitz cosmology in light of new data
We present new observational constraints on Lorentz violating Hořava-Lifshitz cosmological scenarios using an updated cosmological data set from Cosmic Microwave Background (Planck CMB), expansion rates of elliptical and lenticular galaxies, JLA compilation (Joint Light-Curve Analysis) data for Type Ia supernovae (SneIa), Baryon Acoustic Oscillations (BAO) and priors on the Hubble parameter with an alternative parametrisation of the equations. Unlike in other approaches we consider the curvature parameter Ωk as a free parameter in the analysis we considered the parameters Ωk and ΔNν as completely free...
Source: Physics of the Dark Universe - December 19, 2018 Category: Physics Source Type: research

Collapse driven by a scalar field without final singularity
Publication date: Available online 11 December 2018Source: Physics of the Dark UniverseAuthor(s): Jaime M. Hernández, Mauricio Bellini, Claudia MorenoAbstractWe explore a collapsing cosmology driven by a scalar field which is minimally coupled to gravity in a spatially flat and spherically symmetric, isotropic and homogeneous space–time, with a variable timescale that avoid the final singularity. The equation of state that describes the collapse is ω=1. We calculate the back-reaction of the space–time during the collapse and the energy density fluctuations related to this back-reaction has a spectr...
Source: Physics of the Dark Universe - December 11, 2018 Category: Physics Source Type: research

Cosmological constraints on parametrized interacting dark energy
Publication date: Available online 3 December 2018Source: Physics of the Dark UniverseAuthor(s): R. von Marttens, L. Casarini, D.F. Mota, W. ZimdahlAbstractWe reconsider the dynamics of the Universe in the presence of interactions in the cosmological dark sector. A class of interacting models is introduced via a real function fr of the ratio r between the energy densities of the (pressureless) cold dark matter (CDM) and dark energy (DE). The subclass of models for which the ratio r depends only on the scale factor is shown to be equivalent to unified models of the dark sector, i.e. models for which the CDM and DE component...
Source: Physics of the Dark Universe - December 4, 2018 Category: Physics Source Type: research

Probing dark universe with exceptional points
Publication date: Available online 30 November 2018Source: Physics of the Dark UniverseAuthor(s): Maxim Goryachev, Ben McAllister, Michael E. TobarAbstractIt is demonstrated that detection of putative particles such as paraphotons and axions constituting the dark sector of the universe can be reduced to detection of extremely weak links or couplings between cavities and modes. This method allows utilisation of extremely sensitive frequency metrology methods that are not limited by traditional requirements on ultra low temperatures, strong magnetic fields and sophisticated superconducting technology. We show that exceptiona...
Source: Physics of the Dark Universe - December 2, 2018 Category: Physics Source Type: research

Does quartessence ease cosmic tensions?
Publication date: Available online 29 November 2018Source: Physics of the Dark UniverseAuthor(s): Stefano Camera, Matteo Martinelli, Daniele BertaccaAbstractTensions between cosmic microwave background observations and the growth of the large-scale structure inferred from late-time probes pose a serious challenge to the concordance ΛCDM cosmological model. State-of-the-art data from the Planck satellite predicts a higher rate of structure growth than what preferred by low-redshift observables. Such tension has hitherto eluded conclusive explanations in terms of straightforward modifications to ΛCDM,...
Source: Physics of the Dark Universe - November 30, 2018 Category: Physics Source Type: research

Tsallis holographic dark energy in the brane cosmology
Publication date: Available online 28 November 2018Source: Physics of the Dark UniverseAuthor(s): S. Ghaffari, H. Moradpour, Valdir B. Bezerra, J.P. Morais Graça, I.P. LoboAbstractWe study some cosmological features of Tsallis holographic dark energy (THDE) in Cyclic, DGP and RS II braneworlds. In our setup, a flat FRW universe is considered filled by a pressureless source and THDE with the Hubble radius as the IR cutoff, while there is no interaction between them. Our result shows that although suitable behavior can be obtained for the system parameters such as the deceleration parameter, the models are not always ...
Source: Physics of the Dark Universe - November 29, 2018 Category: Physics Source Type: research

Probing primordial features with the primary CMB
Publication date: Available online 22 November 2018Source: Physics of the Dark UniverseAuthor(s): Mario BallardiniAbstractWe propose to study the imprint of features in the primordial power spectrum with the primary CMB after the subtraction of the reconstructed ISW signal from the observed CMB temperature angular power spectrum. We consider the application to features models able to fit two of the large scales anomalies observed in the CMB temperature angular power spectrum: the deficit of power at ℓ∼2 andat ℓ∼22.We show that if the features comes from the primordial power spectrum we should be find consistent...
Source: Physics of the Dark Universe - November 23, 2018 Category: Physics Source Type: research

Testing Horndeski gravity as dark matter with hi_class
Publication date: Available online 16 November 2018Source: Physics of the Dark UniverseAuthor(s): Alessandro Casalino, Massimiliano RinaldiAbstractWe consider a model of dark matter fluid based on a sector of Horndeski gravity. The model is very successful, at the background level, in reproducing the evolution of the Universe from early times to today. However, at the perturbative level the model fails. To show this, we use the code hi_class and we compute the matter power spectrum and the cosmic microwave background spectrum. Our results confirm, in a new and independent way, that this sector of Horndeski gravity is not v...
Source: Physics of the Dark Universe - November 17, 2018 Category: Physics Source Type: research

Axino abundances in high-scale supersymmetry
Publication date: Available online 15 November 2018Source: Physics of the Dark UniverseAuthor(s): Ki-Young Choi, Hyun Min LeeAbstractWe consider the thermal production of axino dark matter in high-scale supersymmetry where all the superparticles except the axino are heavier than the maximum and reheating temperatures. In this case, the axinos are produced dominantly in pairs from the scattering of SM particles in thermal plasma in the early Universe after inflation. We find that the thermal averaged scattering cross section for the axino pair production is given by 〈σv〉∝T4 in Kim-Shifman-Vainstein-Zakharov (...
Source: Physics of the Dark Universe - November 16, 2018 Category: Physics Source Type: research

lenstronomy: Multi-purpose gravitational lens modelling software package
We present lenstronomy, a multi-purpose open-source gravitational lens modeling pythonpackage. lenstronomy is able to reconstruct the lens mass and surface brightness distributions of strong lensing systems using forward modelling. lenstronomy supports a wide range of analytic lens and light models in arbitrary combination. The software is also able to reconstruct complex extended sources (Birrer et. al 2015) as well as being able to model point sources. We designed lenstronomy to be stable, flexible and numerically accurate, with a clear user interface that could be deployed across different platforms. Thro...
Source: Physics of the Dark Universe - November 14, 2018 Category: Physics Source Type: research

Dark Universe and distribution of matter as quantum imprinting
Publication date: Available online 12 November 2018Source: Physics of the Dark UniverseAuthor(s): Ignazio Licata, Gerardo Iovane, Leonardo Chiatti, Elmo Benedetto, Fabrizio TamburiniAbstractIn this paper we want to analyze the Dark Matter problem and the distribution of matter through two different approaches, which are linked by the possibility that the solution of these astronomical puzzles should be sought in the quantum imprinting of the Universe. The first approach is based on a cosmological model formulated and developed in the last ten years by the first and third authors of this paper; the so-called ”Archaic ...
Source: Physics of the Dark Universe - November 14, 2018 Category: Physics Source Type: research

Characterization of the global network of optical magnetometers to search for exotic physics (GNOME)
Publication date: Available online 24 October 2018Source: Physics of the Dark UniverseAuthor(s): S. Afach, D. Budker, G. DeCamp, V. Dumont, Z.D. Grujić, H. Guo, D.F. Jackson Kimball, T.W. Kornack, V. Lebedev, W. Li, H. Masia-Roig, S. Nix, M. Padniuk, C.A. Palm, C. Pankow, A. Penaflor, X. Peng, S. Pustelny, T. Scholtes, J.A. SmigaAbstractThe Global Network of Optical Magnetometers to search for Exotic physics (GNOME) is a network of geographically separated, time-synchronized, optically pumped atomic magnetometers that is being used to search for correlated transient signals heralding exotic physics. The GNOME is sensitive...
Source: Physics of the Dark Universe - October 24, 2018 Category: Physics Source Type: research