Special Issue "keV Warm Dark Matter (ΛWDM) in Agreement with Observations in Tribute to Héctor J. De Vega"

A special issue of Universe (ISSN 2218-1997). This special issue belongs to the section "Gravitation".

Deadline for manuscript submissions: closed (30 November 2021).

Special Issue Editor

Prof. Dr. Norma G. Sanchez
E-Mail Website1 Website2
Guest Editor
Directrice de l'Ecole Internationale d'Astrophysique "Daniel Chalonge - Héctor de Vega", CNRS, Observatoire de Paris - PSL Université-Sorbonne Université, LERMA 77, avenue Denfert-Rochereau 75014 Paris , France
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Special Issue Information

Dear Colleagues,

Research into keV warm dark matter (WDM) is progressing fast. The subject is new and essentially works, naturally reproducing astronomical observations over all scales, from small and intermediate galactic scales to large (cosmological) scales (ΛWDM). Astronomical evidence that Cold Dark Matter (CDM) and its proposed tailored baryonic cures/recipes do not work at the small and galactic scales is staggering.

This Special Issue addresses the clarifying and impressive progress made in keV warm dark matter galaxies in agreement with observations. In the tradition of the Chalonge–de Vega School, an effort of clarification and synthesis is made by combining theory, analysis, observation, and numerical simulation results in a conceptual framework. This Special Issue aims to put together astrophysical, cosmological, particle, and nuclear keV WDM research—including models and experimental searches, theory, and analytical and numerical frameworks— that reproduces astronomical and cosmic observations at all scales.

We invite our colleagues to submit their works to this Special Issue in Tribute to Héctor J. de Vega https://chalonge-devega.fr/HdeV.html.

Mini-reviews can be submitted as well. All submitted papers must include clear purposes, results, and clear conclusions.

This collection of papers will thus register the exciting ongoing theoretical and experimental developments in (i) the search for the leading keV WDM particle candidates and (ii) the impact of keV WDM astrophysics (including its signatures and constraints with high-redshift galaxies and clusters, cosmic recombination, 21 cm line, and implications for star formation) with or for the JWST, HST, SKA, X-ray astronomy, gravitational lensing, and other astronomical observations, as well as news from KATRIN, ECHo, and other experiments.

Exciting keV WDM work to perform is ahead of us.

Prof. Dr. Norma G. Sanchez
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Universe is an international peer-reviewed open access monthly journal published by MDPI.

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Keywords

  • keV warm dark matter
  • keV warm dark matter theory, constraints, and observations
  • keV warm dark matter particle
  • keV warm dark matter (direct and indirect) detection
  • neutrinos and sterile neutrinos
  • dark matter production models
  • direct and indirect searches

Published Papers (7 papers)

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Research

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Article
Warm Dark Matter from Higher-Dimensional Gauge Theories
Universe 2021, 7(12), 462; https://doi.org/10.3390/universe7120462 - 27 Nov 2021
Viewed by 245
Abstract
Warm dark matter particles with masses in the keV range have been linked with the large group representations in gauge theories through a high number of species at decoupling. In this paper, we address WDM fermionic degrees of freedom from such representations. Bridging [...] Read more.
Warm dark matter particles with masses in the keV range have been linked with the large group representations in gauge theories through a high number of species at decoupling. In this paper, we address WDM fermionic degrees of freedom from such representations. Bridging higher-dimensional particle physics theories with cosmology studies and astrophysical observations, our approach is two-folded, i.e., it includes realistic models from higher-dimensional representations and constraints from simulations tested against observations. Starting with superalgebras in exceptional periodicity theories, we discuss several symmetry reductions and we consider several representations that accommodate a high number of degrees of freedom. We isolate a model that naturally accommodates both the standard model representation and the fermionic dark matter in agreement with both large and small-scale constraints. This model considers an intersection of branes in D = 27 + 3 in a manner that provides the degrees of freedom for the standard model on one hand and 2048 fermionic degrees of freedom for dark matter, corresponding to a ∼2 keV particle mass, on the other. In this context, we discuss the theoretical implications and the observable predictions. Full article
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Communication
Nuclear Matter in 1 + 1 Dimensions
Universe 2021, 7(11), 411; https://doi.org/10.3390/universe7110411 - 29 Oct 2021
Viewed by 254
Abstract
We review the solution of QCD in two spacetime dimensions. Following the analysis of Baluni, for a single flavor, the model can be analyzed using Abelian bosonization. The theory can be analyzed in strong coupling, when the quarks are much lighter than the [...] Read more.
We review the solution of QCD in two spacetime dimensions. Following the analysis of Baluni, for a single flavor, the model can be analyzed using Abelian bosonization. The theory can be analyzed in strong coupling, when the quarks are much lighter than the gauge coupling. In this limit, the theory is given by a Luttinger liquid. Full article
Article
The Epoch of Reionization in Warm Dark Matter Scenarios
Universe 2021, 7(10), 365; https://doi.org/10.3390/universe7100365 - 29 Sep 2021
Cited by 1 | Viewed by 463
Abstract
In this paper we investigate how the Reionization process is affected by early galaxy formation in different cosmological scenarios. We use a semi-analytic model with suppressed initial power spectra to obtain the UV Luminosity Function in thermal Warm Dark Matter and sterile neutrino [...] Read more.
In this paper we investigate how the Reionization process is affected by early galaxy formation in different cosmological scenarios. We use a semi-analytic model with suppressed initial power spectra to obtain the UV Luminosity Function in thermal Warm Dark Matter and sterile neutrino cosmologies. We retrace the ionization history of intergalactic medium with hot stellar emission only, exploiting fixed and variable photons escape fraction models (fesc). For each cosmology, we find an upper limit to fixed fesc, which guarantees the completion of the process at z<6.7. The analysis is tested with two limit hypothesis on high-z ionized hydrogen volume fraction, comparing our predictions with observational results. Full article
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Article
Axion–Sterile Neutrino Dark Matter
Universe 2021, 7(10), 354; https://doi.org/10.3390/universe7100354 - 23 Sep 2021
Cited by 3 | Viewed by 502
Abstract
Extending the standard model with three right-handed neutrinos and a simple QCD axion sector can account for neutrino oscillations, dark matter and baryon asymmetry; at the same time, it solves the strong CP problem, stabilizes the electroweak vacuum and can implement critical Higgs [...] Read more.
Extending the standard model with three right-handed neutrinos and a simple QCD axion sector can account for neutrino oscillations, dark matter and baryon asymmetry; at the same time, it solves the strong CP problem, stabilizes the electroweak vacuum and can implement critical Higgs inflation (satisfying all current observational bounds). We perform here a general analysis of dark matter (DM) in such a model, which we call the aνMSM. Although critical Higgs inflation features a (quasi) inflection point of the inflaton potential, we show that DM cannot receive a contribution from primordial black holes in the aνMSM. This leads to a multicomponent axion–sterile neutrino DM and allows us to relate the axion parameters, such as the axion decay constant, to the neutrino parameters. We include several DM production mechanisms: the axion production via misalignment and decay of topological defects as well as the sterile neutrino production through the resonant and non-resonant mechanisms and in the recently proposed CPT-symmetric universe. Full article
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Article
New Bounds for the Mass of Warm Dark Matter Particles Using Results from Fermionic King Model
Universe 2021, 7(8), 308; https://doi.org/10.3390/universe7080308 - 20 Aug 2021
Viewed by 465
Abstract
After reviewing several aspects about the thermodynamics of self-gravitating systems that undergo the evaporation (escape) of their constituents, some recent results obtained in the framework of fermionic King model are applied here to the analysis of galactic halos considering warm dark matter (WDM) [...] Read more.
After reviewing several aspects about the thermodynamics of self-gravitating systems that undergo the evaporation (escape) of their constituents, some recent results obtained in the framework of fermionic King model are applied here to the analysis of galactic halos considering warm dark matter (WDM) particles. According to the present approach, the reported structural parameters of dwarf galaxies are consistent with the existence of a WDM particle with mass in the keV scale. Assuming that the dwarf galaxy Willman 1 belongs to the region III of fermionic King model (whose gravothermal collapse is a continuous phase transition), one obtains the interval 1.2 keV ≤ m ≤ 2.6 keV for the mass of WDM particle. This analysis improves previous estimates by de Vega and co-workers [Astropart. Phys. 46 (2013) 14–22] considering both the quantum degeneration and the incidence of the constituents evaporation. This same analysis evidences that most of galaxies are massive enough to undergo a violent gravothermal collapse (a discontinuous microcanonical phase transition) that leads to the formation of a degenerate core of WDM particles. It is also suggested that quantum-relativistic processes governing the cores of large galaxies (e.g., the formation of supermassive black holes) are somehow related to the gravothermal collapse of the WDM degenerate cores when the total mass of these systems are comparable to the quantum-relativistic characteristic mass Mc=c/G3/2m21012M obtained for WDM particles with mass m in the keV scale. The fact that a WDM particle with mass in the keV scale seems to be consistent with the observed properties of dwarf and large galaxies provides a strong support to this dark matter candidate. Full article
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Article
Sterile Neutrinos as Dark Matter: Alternative Production Mechanisms in the Early Universe
Universe 2021, 7(8), 264; https://doi.org/10.3390/universe7080264 - 25 Jul 2021
Viewed by 446
Abstract
We study various production mechanisms of sterile neutrinos in the early universe beyond and within the standard model. We obtain the quantum kinetic equations for production and the distribution function of sterile-like neutrinos at freeze-out, from which we obtain free streaming lengths, equations [...] Read more.
We study various production mechanisms of sterile neutrinos in the early universe beyond and within the standard model. We obtain the quantum kinetic equations for production and the distribution function of sterile-like neutrinos at freeze-out, from which we obtain free streaming lengths, equations of state and coarse grained phase space densities. In a simple extension beyond the standard model, in which neutrinos are Yukawa coupled to a Higgs-like scalar, we derive and solve the quantum kinetic equation for sterile production and analyze the freeze-out conditions and clustering properties of this dark matter constituent. We argue that in the mass basis, standard model processes that produce active neutrinos also yield sterile-like neutrinos, leading to various possible production channels. Hence, the final distribution function of sterile-like neutrinos is a result of the various kinematically allowed production processes in the early universe. As an explicit example, we consider production of light sterile neutrinos from pion decay after the QCD phase transition, obtaining the quantum kinetic equation and the distribution function at freeze-out. A sterile-like neutrino with a mass in the keV range produced by this process is a suitable warm dark matter candidate with a free-streaming length of the order of few kpc consistent with cores in dwarf galaxies. Full article
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Review

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Review
Fundamental Properties of the Dark and the Luminous Matter from the Low Surface Brightness Discs
Universe 2021, 7(9), 344; https://doi.org/10.3390/universe7090344 - 13 Sep 2021
Viewed by 531
Abstract
Dark matter (DM) is one of the biggest mystery in the Universe. In this review, we start reporting the evidences for this elusive component and discussing about the proposed particle candidates and scenarios for such phenomenon. Then, we focus on recent results obtained [...] Read more.
Dark matter (DM) is one of the biggest mystery in the Universe. In this review, we start reporting the evidences for this elusive component and discussing about the proposed particle candidates and scenarios for such phenomenon. Then, we focus on recent results obtained for rotating disc galaxies, in particular for low surface brightness (LSB) galaxies. The main observational properties related to the baryonic matter in LSBs, investigated over the last decades, are briefly recalled. Next, these galaxies are analyzed by means of the mass modelling of their rotation curves both individual and stacked. The latter analysis, via the universal rotation curve (URC) method, results really powerful in giving a global or universal description of the properties of these objects. We report the presence in LSBs of scaling relations among their structural properties that result comparable with those found in galaxies of different morphologies. All this confirms, in disc systems, the existence of a strong entanglement between the luminous matter (LM) and the dark matter (DM). Moreover, we report how in LSBs the tight relationship between their radial gravitational accelerations g and their baryonic components gb results to depend also on the stellar disk length scale and the radius at which the two accelerations have been measured. LSB galaxies strongly challenge the ΛCDM scenario with the relative collisionless dark particle and, alongside with the non-detection of the latter, contribute to guide us towards a new scenario for the DM phenomenon. Full article
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