scholarly journals A model for mixed warm and hot right-handed neutrino dark matter

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Maíra Dutra ◽  
Vinícius Oliveira ◽  
C. A de S. Pires ◽  
Farinaldo S. Queiroz
Keyword(s):  
Dark Matter ◽  
Degrees Of Freedom ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Matter Density ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Sterile Neutrinos ◽  
Dark Matter Density ◽  
Model Features

Abstract We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same SU(3)L multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom.

Thermal relics

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dark Matter Particle ◽  
Big Bang ◽  
Matter Density ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Boltzmann Equations ◽  
Hubble Rate ◽  
Dark Matter Density

The Boltzmann equations, which describe processes as diverse as the evolution of the dark matter density, big bang nucleosynthesis or recombination, are derived. The Gamov criterion states that processes freeze-out when their rate becomes smaller than the Hubble rate. It is demonstrated that the mass of any thermal relic is bounded by ≲ 20TeV, while the abundance of a cold dark matter particle with 〈σ‎v〉 ≃ 3 × 10−26 cm3/s corresponds to the observed one, Ω‎CDM = 0.2. Big bang nucleosynthesis, which successfully explains the abundance of light elements like D and 4He, is discussed.

scholarly journals THE STATUS OF NEUTRINO MASS

1998 ◽  
Vol 13 (25) ◽  
pp. 4409-4423 ◽  
Author(s):  
DAVID O. CALDWELL
Keyword(s):  
Dark Matter ◽  
Neutrino Mass ◽  
Heavy Element ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Atmospheric Neutrinos ◽  
Big Bang Nucleosynthesis ◽  
Robust Solution ◽  
The Status ◽  
Mass Pattern

New experimental results, if correct, require at least one light sterile neutrino, in addition to the three active ones, to accommodate the mass differences required to explain the solar νe deficit, the anomalous μ/e ratio produced by atmospheric neutrinos, and either the candidate events for νμ→ νe (or [Formula: see text]) from the LSND experiment, or the possible need for a hot component of dark matter. This neutrino mass pattern can not only accommodate all these four requirements, but also provide a robust solution to a problem presently making heavy-element synthesis by supernovae impossible and resolve a possible discrepancy between big bang nucleosynthesis theory and observations.

Sterile neutrinos and Big Bang Nucleosynthesis in the 3 + 1 scheme

2014 ◽  
Vol 23 (03) ◽  
pp. 1450014 ◽  
Author(s):  
Mercedes Elisa Mosquera ◽  
Osvaldo Civitarese
Keyword(s):  
Distribution Function ◽  
Sterile Neutrino ◽  
Big Bang ◽  
Light Nuclei ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Normalization Constant ◽  
Big Bang Nucleosynthesis ◽  
Sterile Neutrinos ◽  
Mixing Angle ◽  
Free Parameters

We study the effects of adding a sterile neutrino to three active neutrinos (3 + 1 scheme) in the calculation of primordial abundances. Taking the normalization constant (a) of the occupation factor of the sterile neutrino and the active-sterile mixing angle (ϕ) as free parameters, we calculate the neutrino distribution function and primordial abundances of light nuclei. We set constrains on these parameters by using the available data on the abundances of D, 4 He and 7 Li . Results are consistent with small values of a and ϕ. The extracted value of the baryon-to-photon ratio (ηB), which is constrained by the Wilkinson Microwave Anisotropy Probe (WMAP) value [Formula: see text], and Planck observations, depends strongly on the inclusion of the lithium data in the fit.

scholarly journals New constraints on the mass of fermionic dark matter from dwarf spheroidal galaxies

2020 ◽  
Vol 501 (1) ◽  
pp. 1188-1201
Author(s):  
James Alvey ◽  
Nashwan Sabti ◽  
Victoria Tiki ◽  
Diego Blas ◽  
Kyrylo Bondarenko ◽  
...  
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Pauli Principle ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Sterile Neutrinos ◽  
Dwarf Spheroidal Galaxies ◽  
Dark Matter Mass ◽  
Model Independent ◽  
Spheroidal Galaxies

ABSTRACT Dwarf spheroidal galaxies are excellent systems to probe the nature of fermionic dark matter due to their high observed dark matter phase-space density. In this work, we review, revise, and improve upon previous phase-space considerations to obtain lower bounds on the mass of fermionic dark matter particles. The refinement in the results compared to previous works is realized particularly due to a significantly improved Jeans analysis of the galaxies. We discuss two methods to obtain phase-space bounds on the dark matter mass, one model-independent bound based on Pauli’s principle, and the other derived from an application of Liouville’s theorem. As benchmark examples for the latter case, we derive constraints for thermally decoupled particles and (non-)resonantly produced sterile neutrinos. Using the Pauli principle, we report a model-independent lower bound of $m \ge 0.18\, \mathrm{keV}$ at 68 per cent CL and $m \ge 0.13\, \mathrm{keV}$ at 95 per cent CL. For relativistically decoupled thermal relics, this bound is strengthened to $m \ge 0.59\, \mathrm{keV}$ at 68 per cent CL and $m \ge 0.41\, \mathrm{keV}$ at 95 per cent CL, while for non-resonantly produced sterile neutrinos the constraint is $m \ge 2.80\, \mathrm{keV}$ at 68 per cent CL and $m \ge 1.74\, \mathrm{keV}$ at 95 per cent CL. Finally, the phase-space bounds on resonantly produced sterile neutrinos are compared with complementary limits from X-ray, Lyman α, and big bang nucleosynthesis observations.

scholarly journals BBN CONSTRAINTS ON NEUTRINO OSCILLATIONS PARAMETERS RELAXED OR STRENGTHENED

2007 ◽  
Vol 16 (07) ◽  
pp. 1197-1210 ◽  
Author(s):  
DANIELA KIRILOVA
Keyword(s):  
Energy Spectrum ◽  
Energy Density ◽  
Sterile Neutrino ◽  
Full Range ◽  
Big Bang ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Cosmic Expansion ◽  
Cosmological Constraints ◽  
Kinetic Effects

Big Bang Nucleosynthesis (BBN) with nonequilibrium νe ↔ νs oscillations, in the more general case of non-zero population of νs before oscillations δNs ≠ 0, is discussed. 4 He primordial production Yp(δNs) in the presence of νe ↔ νs oscillations for different initial populations of the sterile neutrino state 0 ≤ δ Ns ≤ 1 and the full range of oscillation parameters is calculated. Non-zero δNs has a two-fold effect on 4 He : (i) it enhances the energy density and hence increases the cosmic expansion rate, leading to Ypoverproduction, and (ii) it suppresses the kinetic effects of oscillations on BBN, namely, the effects on pre-BBN nucleon kinetics, caused by the νe energy spectrum distortion and the [Formula: see text] asymmetry generation by oscillations, leading to decreased Yp production. Depending on oscillation parameters one or the other effect may dominate, causing, correspondingly, either a relaxation of the cosmological constraints or their strengthening with the increase of δNs. More general BBN constraints on νe ↔ νs oscillation parameters, corresponding to 3% Yp overproduction, for different initial populations of the sterile state are calculated. Previous BBN constraints were derived assuming empty sterile state before oscillations. It is shown that the cosmological constraints strengthen with the increase of δNs value, the change being more considerable for nonresonant oscillations.

scholarly journals Determining the local dark matter density with LAMOST data

2016 ◽  
Vol 458 (4) ◽  
pp. 3839-3850 ◽  
Author(s):  
Qiran Xia ◽  
Chao Liu ◽  
Shude Mao ◽  
Yingyi Song ◽  
Lan Zhang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Matter Density ◽  
Dark Matter Density

scholarly journals Searching for space-time variation of the fine structure constant using QSO spectra: overview and future prospects

2009 ◽  
Vol 5 (H15) ◽  
pp. 304-304
Author(s):  
J. C. Berengut ◽  
V. A. Dzuba ◽  
V. V. Flambaum ◽  
J. A. King ◽  
M. G. Kozlov ◽  
...  
Keyword(s):  
Nuclear Reactor ◽  
Structure Constant ◽  
Big Bang ◽  
The Other ◽  
Fine Structure Constant ◽  
Spatial And Temporal Variation ◽  
Fundamental Constants ◽  
Future Prospects ◽  
Big Bang Nucleosynthesis ◽  
The Universe

Current theories that seek to unify gravity with the other fundamental interactions suggest that spatial and temporal variation of fundamental constants is a possibility, or even a necessity, in an expanding Universe. Several studies have tried to probe the values of constants at earlier stages in the evolution of the Universe, using tools such as big-bang nucleosynthesis, the Oklo natural nuclear reactor, quasar absorption spectra, and atomic clocks (see, e.g. Flambaum & Berengut (2009)).

scholarly journals Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

2010 ◽  
Vol 514 ◽  
pp. A47 ◽  
Author(s):  
S. Pasetto ◽  
E. K. Grebel ◽  
P. Berczik ◽  
R. Spurzem ◽  
W. Dehnen
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Matter Density ◽  
Density Profiles ◽  
Dark Matter Density

scholarly journals Non-Gaussian inference from non-linear and non-Poisson biased distributed data

2014 ◽  
Vol 10 (S306) ◽  
pp. 258-261
Author(s):  
Metin Ata ◽  
Francisco-Shu Kitaura ◽  
Volker Müller
Keyword(s):  
Dark Matter ◽  
Statistical Inference ◽  
Computer Code ◽  
Matter Density ◽  
Density Field ◽  
Distributed Data ◽  
Dark Matter Density ◽  
Posterior Sampling ◽  
Non Linear ◽  
Non Gaussian

AbstractWe study the statistical inference of the cosmological dark matter density field from non-Gaussian, non-linear and non-Poisson biased distributed tracers. We have implemented a Bayesian posterior sampling computer-code solving this problem and tested it with mock data based onN-body simulations.

scholarly journals Li isotopes in metal-poor halo dwarfs: a more and more complicated story

2009 ◽  
Vol 5 (S268) ◽  
pp. 201-210
Author(s):  
Monique Spite ◽  
François Spite
Keyword(s):  
Cosmic Rays ◽  
Big Bang ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Lithium Abundance ◽  
The Galaxy ◽  
Li Isotope ◽  
Low Metallicity ◽  
The Big Bang ◽  
Early Galaxy

AbstractThe nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis.The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the ν process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient) warm galactic stars should retain the signature of these processes if, (as it had been often expected) lithium is not depleted in these stars. The existence of a “plateau” of the abundance of 7Li (and of its slope) in the warm metal-poor stars is discussed. At very low metallicity ([Fe/H] < −2.7dex) the star to star scatter increases significantly towards low Li abundances. The highest value of the lithium abundance in the early stellar matter of the Galaxy (logϵ(Li) = A(7Li) = 2.2 dex) is much lower than the the value (logϵ(Li) = 2.72) predicted by the standard Big Bang nucleosynthesis, according to the specifications found by the satellite WMAP. After gathering a homogeneous stellar sample, and analysing its behaviour, possible explanations of the disagreement between Big Bang and stellar abundances are discussed (including early astration and diffusion). On the other hand, possibilities of lower productions of 7Li in the standard and/or non-standard Big Bang nucleosyntheses are briefly evoked.A surprisingly high value (A(6Li)=0.8 dex) of the abundance of the 6Li isotope has been found in a few warm metal-poor stars. Such a high abundance of 6Li independent of the mean metallicity in the early Galaxy cannot be easily explained. But are we really observing 6Li?

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