scholarly journals Detecting ultralight axion dark matter wind with laser interferometers

2016 ◽  
Vol 26 (07) ◽  
pp. 1750063 ◽  
Author(s):  
Arata Aoki ◽  
Jiro Soda
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Modified Gravity ◽  
Laser Interferometer ◽  
Mass Range ◽  
Dark Matter Halo ◽  
Detector Signal ◽  
Modified Gravity Theory ◽  
Axion Field ◽  
Laser Interferometers

The ultralight axion with mass around [Formula: see text][Formula: see text]eV is known as a candidate of dark matter. A peculiar feature of the ultralight axion is oscillating pressure in time, which produces oscillation of gravitational potentials. Since the solar system moves through the dark matter halo at the velocity of about [Formula: see text], there exists axion wind, which looks like scalar gravitational waves for us. Hence, there is a chance to detect ultralight axion dark matter with a wide mass range by using laser interferometer detectors. We calculate the detector signal induced by the oscillating pressure of the ultralight axion field, which would be detected by future laser interferometer experiments. We also argue that the detector signal can be enhanced due to the resonance in modified gravity theory explaining the dark energy.

scholarly journals A model for core formation in dark matter haloes and ultra-diffuse galaxies by outflow episodes

2019 ◽  
Vol 491 (3) ◽  
pp. 4523-4542 ◽  
Author(s):  
Jonathan Freundlich ◽  
Avishai Dekel ◽  
Fangzhou Jiang ◽  
Guy Ishai ◽  
Nicolas Cornuault ◽  
...  
Keyword(s):  
Dark Matter ◽  
Mass Gain ◽  
Mass Range ◽  
Dark Matter Halo ◽  
Specific Mass ◽  
Spherical System ◽  
Energy Conserving ◽  
Parameter Function ◽  
Two Parameter ◽  
Analytic Potential

ABSTRACT We present a simple model for the response of a dissipationless spherical system to an instantaneous mass change at its centre, describing the formation of flat cores in dark matter haloes and ultra-diffuse galaxies (UDGs) from feedback-driven outflow episodes in a specific mass range. This model generalizes an earlier simplified analysis of an isolated shell into a system with continuous density, velocity, and potential profiles. The response is divided into an instantaneous change of potential at constant velocities due to a given mass-loss or mass-gain, followed by energy-conserving relaxation to a new Jeans equilibrium. The halo profile is modelled by a two-parameter function with a variable inner slope and an analytic potential profile, which enables determining the associated kinetic energy at equilibrium. The model is tested against NIHAO cosmological zoom-in simulations, where it successfully predicts the evolution of the inner dark matter profile between successive snapshots in about 75 per cent of the cases, failing mainly in merger situations. This model provides a simple understanding of the formation of dark matter halo cores and UDGs by supernova-driven outflows, and a useful analytic tool for studying such processes.

scholarly journals Do we come from a quantum anomaly?

2019 ◽  
Vol 28 (14) ◽  
pp. 1944002 ◽  
Author(s):  
Spyros Basilakos ◽  
Nick E. Mavromatos ◽  
Joan Solà Peracaula
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Hubble Parameter ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Quantum Anomaly ◽  
Inflationary Phase ◽  
Axion Field ◽  
The Universe

We present a string-based picture of the cosmological evolution in which (CP-violating) gravitational anomalies acting during the inflationary phase of the universe cause the vacuum energy density to “run” with the effective Hubble parameter squared, [Formula: see text], thanks to the axion field of the bosonic string multiplet. This leads to baryogenesis through leptogenesis with massive right-handed neutrinos. The generation of chiral matter after inflation helps in cancelling the anomalies in the observable radiation- and matter-dominated eras. The present era inherits the same “running vacuum” structure triggered during the inflationary time by the axion field. The current dark energy is thus predicted to be mildly dynamical, and dark matter should be made of axions. Paraphrasing Carl Sagan [ https://www.goodreads.com/author/quotes/10538.Carl_Sagan .]: we are all anomalously made from starstuff.

MODIFIED GRAVITY THEORY DUE TO POSITIVE AS WELL AS NEGATIVE CURVATURE INDUCED ACCELERATION

2012 ◽  
Vol 21 (02) ◽  
pp. 1250012
Author(s):  
PRIYADARSHI MAJUMDAR
Keyword(s):  
Dark Energy ◽  
Modified Gravity ◽  
Negative Curvature ◽  
Gravity Theory ◽  
Cosmic Acceleration ◽  
Late Time ◽  
Negative Power ◽  
Modified Gravity Theory ◽  
Phase Q ◽  
The Universe

We formulate a modified gravity theory that eliminates the need for dark energy and is stable for a Lagrangian containing R, R2 as well as 1/R terms (i.e. nonlinear contributions of the Ricci curvature with a non-analytic model of f(R) at R = 0) without considering any matter-dominated era. The terms with positive powers (1, 2) of the curvature support the inflationary epoch while the terms with negative power (-1) serves as effective dark energy, supporting current cosmic acceleration. We present a few analytical solutions of evolution equation for the deceleration parameter q as a function of Hubble parameter H and time t; specially in one solution, the universe evolves continuously from q = 1 (a radiation-dominated epoch) to q = -1/2 (dark-energy-dominated late-time accelerating phase) when the universe is sufficiently old. The solution is supported by numerical results. The transition from the decelerated (q > 0) to the accelerated phase (q < 0) of expansion takes place smoothly without having to resort to a study of asymptotic behavior.

Interacting cosmological viscous fluid with Little Rip and Pseudo Rip solutions in f(R) gravity

2018 ◽  
Vol 15 (02) ◽  
pp. 1850028 ◽  
Author(s):  
R. D. Boko ◽  
M. J. S. Houndjo ◽  
J. Tossa
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Viscous Fluid ◽  
Modified Gravity ◽  
Infinite Time ◽  
Two Fluids ◽  
Viscosity Models ◽  
Time Singularities ◽  
Analytic Expressions

In this paper, we investigate the evolution of the equation of state of the interacting viscous dark energy in [Formula: see text] gravity. We first consider the case when the dark energy does not interact with the dark matter and after, the case where there is a coupling between these dark components. The viscosity and the interaction between the two fluids are parameterized by constants [Formula: see text] and [Formula: see text] respectively for which a detailed investigation on the cosmological implications has been done. In the later part of the paper, we explore some bulk viscosity models with Little and Pseudo Rip infinite time singularities within [Formula: see text] modified gravity. We obtain analytic expressions for characteristic properties of these cosmological models.

A study on the modified holographic Ricci dark energy in logarithmic f(T) gravity

2013 ◽  
Vol 91 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Antonio Pasqua ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Modified Gravity ◽  
State Parameter ◽  
Ricci Dark Energy ◽  
Equation Of State Parameter ◽  
Interaction Term ◽  
The Universe

In this paper, we have studied and investigated the behavior of a modified holographic Ricci dark energy (DE) model interacting with pressureless dark matter (DM) under the theory of modified gravity, dubbed logarithmic f(T) gravity. We have chosen the interaction term between DE and DM in the form Q = 3γHρm and investigated the behavior of the torsion, T, the Hubble parameter, H, the equation of state parameter, ωDE, the energy density of DE, ρDE, and the energy density contribution due to torsion, ρT, as functions of the redshift, z. We have found that T increases with the redshift, z, H increases with the evolution of the universe, ωDE has a quintessence-like behavior, and both energy densities increase going from higher to lower redshifts.

scholarly journals On the Fundamental Particles and Reactions of Nature

2020 ◽  
Author(s):  
Jian-Bin Bao ◽  
Nicholas Bao
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Dynamic Equilibrium ◽  
Big Bang ◽  
Equal Mass ◽  
Dark Matter Halo ◽  
Constant Density ◽  
White Hole ◽  
Fundamental Particles ◽  
Degeneracy Pressure

There are unsolved problems related to inflation, gravity, dark matter, dark energy, and the fate of the universe. Some of them can be better answered by assuming the existence of aether and hypoatoms. Both were created during the inflation in the very early universe. While aether forms vacuum, hypoatoms form all observable matter. In vacuum, aether exists between the particle-antiparticle form and the energy form in a dynamic equilibrium: A + A-bar = gamma + gamma, resulting in quantum phenomena and a character of negative pressure. The proposed hypoatom has an antimatter nucleus, with an equal mass of matter particles of aether in its perimeter, so the enigma of missing antimatter does not exist. At hypoatoms, the forward reaction of the aether annihilation dominates. With constant-density dark energy, the annihilation constantly consumes the aether in vacuum, producing a sink flow of aether that warps spacetime, and thus generates gravity and a dark matter halo in the vicinity of massive objects. The hypoatom is believed to be a neutrino n1, with a mass of 5 meV. Based on the hypoatom structure, singularities do not exist inside black holes; their cores are hypoatom stars or neutrino stars. By gaining enough mass, ca. , to exceed neutrino degeneracy pressure, a black hole collapses or annihilates into the singularity, thus turning itself into a white hole or a new Big Bang.

scholarly journals Searching For Dark Matter With Gravitational Microlensing: A Report From The MACHO Collaboration

1996 ◽  
Vol 173 ◽  
pp. 209-214
Author(s):  
C.W. Stubbs ◽  
C. Alcock ◽  
R.A. Allsman ◽  
D. Alves ◽  
T.S. Axelrod ◽  
...  
Keyword(s):  
Dark Matter ◽  
Optical Depth ◽  
Galactic Center ◽  
Mass Range ◽  
Dark Matter Halo ◽  
Important Constraint ◽  
Gravitational Microlensing ◽  
The Galaxy ◽  
Straightforward Interpretation

Gravitational microlensing is the most straightforward interpretation of the stellar brightenings that have been observed by our team and other experiments. These data have provided some of the most stringent limits to date on the nature of the Galaxy's dark matter halo. The number of events seen towards the LMC indicate that our Galaxy is not surrounded by a “standard” halo of MACHOs in the mass range of 10–6 to 0.3 solar masses. The observed optical depth towards the Galactic Center is an important constraint on the distribution of mass in the plane of the Galaxy.

scholarly journals Imprints of dark energy on cosmic structure formation – III. Sparsity of dark matter halo profiles

2013 ◽  
Vol 437 (3) ◽  
pp. 2328-2339 ◽  
Author(s):  
I. Balmès ◽  
Y. Rasera ◽  
P.-S. Corasaniti ◽  
J.-M. Alimi
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Structure Formation ◽  
Dark Matter Halo

scholarly journals Beyond ΛCDM with H i intensity mapping: robustness of cosmological constraints in the presence of astrophysics

2020 ◽  
Vol 496 (4) ◽  
pp. 4115-4126 ◽  
Author(s):  
Stefano Camera ◽  
Hamsa Padmanabhan
Keyword(s):  
Dark Matter ◽  
Modified Gravity ◽  
Cosmological Parameters ◽  
Neutral Hydrogen ◽  
Temperature Fluctuations ◽  
Dark Matter Halo ◽  
Cosmological Constraints ◽  
Intensity Mapping ◽  
Standard Cosmological Model ◽  
First Time

ABSTRACT Mapping the unresolved intensity of the 21-cm emission of neutral hydrogen (H i) is now regarded as one the most promising tools for cosmological investigation in the coming decades. Here, we investigate, for the first time, extensions of the standard cosmological model, such as modified gravity and primordial non-Gaussianity, taking self-consistently into account. The present constraints on the astrophysics of H i clustering in the treatment of the brightness temperature fluctuations. To understand the boundaries within which results thus obtained can be considered reliable, we examine the robustness of cosmological parameter estimation performed via studies of 21-cm intensity mapping, against our knowledge of the astrophysical processes leading to H i clustering. Modelling of astrophysical effects affects cosmological observables through the relation linking the overall H i mass in a bound object, to the mass of the underlying dark matter halo that hosts it. We quantify the biases in estimates of standard cosmological parameters and those describing modified gravity and primordial non-Gaussianity that are obtained if one misconceives the slope of the relation between H i mass and halo mass, or the lower virial velocity cut-off for a dark matter halo to be able to host H i. Remarkably, we find that astrophysical uncertainties will not affect searches for primordial non-Gaussianity – one of the strongest science cases for H i intensity mapping – despite the signal being deeply linked to the H i bias.

scholarly journals HYBRID MODIFIED GRAVITY UNIFYING LOCAL TESTS, GALACTIC DYNAMICS AND LATE-TIME COSMIC ACCELERATION

2013 ◽  
Vol 22 (12) ◽  
pp. 1342006 ◽  
Author(s):  
SALVATORE CAPOZZIELLO ◽  
TIBERIU HARKO ◽  
FRANCISCO S. N. LOBO ◽  
GONZALO J. OLMO
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Field ◽  
Modified Gravity ◽  
A Priori ◽  
Cosmic Acceleration ◽  
Galactic Dynamics ◽  
Late Time ◽  
Unified Approach ◽  
Local Constraints

The nonequivalence between the metric and Palatini formalisms of f(R) gravity is an intriguing feature of these theories. However, in the recently proposed hybrid metric-Palatini gravity, consisting of the superposition of the metric Einstein–Hilbert Lagrangian with an [Formula: see text] term constructed à la Palatini, the "true" gravitational field is described by the interpolation of these two nonequivalent approaches. The theory predicts the existence of a light long-range scalar field, which passes the local constraints and affects the galactic and cosmological dynamics. Thus, the theory opens new possibilities for a unified approach, in the same theoretical framework, to the problems of dark energy and dark matter, without distinguishing a priori matter and geometric sources, but taking their dynamics into account under the same standard.

Sign in / Sign up

Export Citation Format

Share Document