scholarly journals Reheating-induced axion dark matter after low scale inflation

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Takeshi Kobayashi ◽  
Lorenzo Ubaldi
Keyword(s):  
Dark Matter ◽  
Zero Temperature ◽  
Axion Mass ◽  
Cosmological Scenario ◽  
Frame Work

Abstract A kinetic mixing between the axion and the inflaton allows for a production of axion dark matter even if the inflationary Hubble scale is smaller than the zero-temperature axion mass. We analyze the axion dynamics in this recently discovered “inflaxion” frame- work, and present a new cosmological scenario where the axion drifts away from its vacuum during the reheating epoch, giving rise to the observed dark matter abundance. We discuss the implications for both the QCD axion and axion-like particles.

scholarly journals Emergent Universe as an interaction in the dark sector

2017 ◽  
Vol 32 (28) ◽  
pp. 1750152
Author(s):  
Emiliano Marachlian ◽  
I. E. Sánchez G. ◽  
Osvaldo P. Santillán
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Linear Equation ◽  
Vacuum Energy ◽  
Cosmological Parameters ◽  
Emergent Universe ◽  
Dark Sector ◽  
Cosmological Scenario ◽  
Friedmann Robertson Walker

A cosmological scenario where dark matter interacts with a variable vacuum energy for a spatially flat Friedmann–Robertson–Walker (FRW) spacetime is proposed and analyzed to show that with a linear equation of state and a particular interaction in the dark sector it is possible to get a model of an Emergent Universe. In addition, the viability of two particular models is studied by taking into account the recent observations. The updated observational Hubble data and the JLA supernovae data are used in order to constraint the cosmological parameters of the models and estimate the amount of dark energy in the radiation era. It is shown that the two models fulfil the severe bounds of [Formula: see text] at the 2[Formula: see text] level of Planck.

A tilted cold dark matter cosmological scenario

1992 ◽  
Vol 399 ◽  
pp. L11 ◽  
Author(s):  
Renyue Cen ◽  
Nickolay Y. Gnedin ◽  
Lev A. Kofman ◽  
Jeremiah P. Ostriker
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Cosmological Scenario

scholarly journals Kantowski–Sachs Tsallis holographic dark energy model with sign-changeable interaction

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Y. Sobhanbabu ◽  
M. Vijaya Santhi
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Deceleration Parameter ◽  
Graphical Representation ◽  
Holographic Dark Energy ◽  
State Parameter ◽  
Field Equations ◽  
Dynamical Parameters ◽  
Frame Work ◽  
The Stability

AbstractIn this work devoted to the investigation of the Tsallis holographic dark energy (IR cut-off is Hubble radius) in homogeneous and anisotropic Kantowski–Sachs Universe within the frame-work of Saez–Ballester scalar tensor theory of gravitation. We have constructed non-interacting and interacting Tsallis holographic dark energy models by solving the field equations using the relationship between the metric potentials. This relation leads to a viable deceleration parameter model which exhibits a transition of the Universe from deceleration to acceleration. In interacting case, we focus on sign-changeable interaction between Tsallis holographic dark energy and dark matter. The dynamical parameters like equation of state parameter, energy densities of Tsallis holographic dark energy and dark matter, deceleration parameter, and statefinder parameters of the models are explained through graphical representation. And also, we discussed the stability analysis of the our models.

scholarly journals Probing ultra-light axion dark matter from 21 cm tomography using Convolutional Neural Networks

2022 ◽  
Vol 2022 (01) ◽  
pp. 020
Author(s):  
Cristiano G. Sabiu ◽  
Kenji Kadota ◽  
Jacobo Asorey ◽  
Inkyu Park
Keyword(s):  
Dark Matter ◽  
Temperature Field ◽  
Brightness Temperature ◽  
Neutral Hydrogen ◽  
Mass Range ◽  
Training Data ◽  
Small Scale ◽  
Axion Mass ◽  
Density Perturbations ◽  
Square Kilometer Array

Abstract We present forecasts on the detectability of Ultra-light axion-like particles (ULAP) from future 21 cm radio observations around the epoch of reionization (EoR). We show that the axion as the dominant dark matter component has a significant impact on the reionization history due to the suppression of small scale density perturbations in the early universe. This behavior depends strongly on the mass of the axion particle. Using numerical simulations of the brightness temperature field of neutral hydrogen over a large redshift range, we construct a suite of training data. This data is used to train a convolutional neural network that can build a connection between the spatial structures of the brightness temperature field and the input axion mass directly. We construct mock observations of the future Square Kilometer Array survey, SKA1-Low, and find that even in the presence of realistic noise and resolution constraints, the network is still able to predict the input axion mass. We find that the axion mass can be recovered over a wide mass range with a precision of approximately 20%, and as the whole DM contribution, the axion can be detected using SKA1-Low at 68% if the axion mass is M X < 1.86 × 10-20 eV although this can decrease to M X < 5.25 × 10-21 eV if we relax our assumptions on the astrophysical modeling by treating those astrophysical parameters as nuisance parameters.

scholarly journals Axion core–halo mass and the black hole–halo mass relation: constraints on a few parsec scales

2019 ◽  
Vol 488 (4) ◽  
pp. 4497-4503 ◽  
Author(s):  
Vincent Desjacques ◽  
Adi Nusser
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Numerical Simulations ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Mass Relation ◽  
Axion Mass

ABSTRACT If the dark matter is made of ultralight axions, stable solitonic cores form at the centres of virialized haloes. In some range for the mass m of the axion particle, these cores are sufficiently compact and can mimic supermassive black holes (SMBH) residing at galactic nuclei. We use the solitonic core–halo mass relation, validated in numerical simulations, to constrain a new range of allowed axion mass from measurements of the SMBH mass in (pseudo)bulge and bulgeless galaxies. These limits are based on observations of galactic nuclei on scales smaller than 10 pc. Our analysis suggests that $m\lesssim 10^{-18}\, {\rm eV}$ is ruled out by the data. We briefly discuss whether an attractive self-interaction among axions could alleviate this constraint.

scholarly journals An Experiment and Detection Scheme for Cavity-Based Light Cold Dark Matter Particle Searches

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Masroor H. S. Bukhari ◽  
Zahoor H. Shah
Keyword(s):  
Dark Matter ◽  
Electromagnetic Interference ◽  
Cold Dark Matter ◽  
Dark Matter Particle ◽  
High Electron Mobility Transistor ◽  
Low Noise ◽  
High Electron ◽  
Detection Scheme ◽  
Axion Mass ◽  
Resonance Detection

A resonance detection scheme and some useful ideas for cavity-based searches of light cold dark matter particles (such as axions) are presented, as an effort to aid in the on-going endeavors in this direction as well as for future experiments, especially in possibly developing a table-top experiment. The scheme is based on our idea of a resonant detector, incorporating an integrated tunnel diode (TD) and GaAs HEMT/HFET (High-Electron Mobility Transistor/Heterogeneous FET) transistor amplifier, weakly coupled to a cavity in a strong transverse magnetic field. The TD-amplifier combination is suggested as a sensitive and simple technique to facilitate resonance detection within the cavity while maintaining excellent noise performance, whereas our proposed Halbach magnet array could serve as a low-noise and permanent solution replacing the conventional electromagnets scheme. We present some preliminary test results which demonstrate resonance detection from simulated test signals in a small optimal axion mass range with superior signal-to-noise ratios (SNR). Our suggested design also contains an overview of a simpler on-resonance dc signal read-out scheme replacing the complicated heterodyne read-out. We believe that all these factors and our propositions could possibly improve or at least simplify the resonance detection and read-out in cavity-based DM particle detection searches (and other spectroscopy applications) and reduce the complications (and associated costs), in addition to reducing the electromagnetic interference and background.

scholarly journals Dynamical system analysis for DBI dark energy interacting with dark matter

2015 ◽  
Vol 30 (02) ◽  
pp. 1550009 ◽  
Author(s):  
Nilanjana Mahata ◽  
Subenoy Chakraborty
Keyword(s):  
Dynamical System ◽  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
System Analysis ◽  
Einstein Field Equation ◽  
Field Equations ◽  
Cosmological Scenario ◽  
Kinetic Energy Term ◽  
Autonomous Dynamical System

A dynamical system analysis related to Dirac–Born–Infeld (DBI) cosmological model has been investigated in this present work. For spatially flat FRW spacetime, the Einstein field equation for DBI scenario has been used to study the dynamics of DBI dark energy interacting with dark matter. The DBI dark energy model is considered as a scalar field with a nonstandard kinetic energy term. An interaction between the DBI dark energy and dark matter is considered through a phenomenological interaction between DBI scalar field and the dark matter fluid. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables. The potential of the DBI scalar field is assumed to be exponential. Finally, critical points are determined, their nature have been analyzed and corresponding cosmological scenario has been discussed.

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