Submit to Universe Review for Universe Propose a Special Issue

Journal Menu

Journal Browser

► Journal Browser

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

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

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

Deadline for manuscript submissions: closed (1 September 2023) | Viewed by 23998

Share This Special Issue

Special Issue Editor

Prof. Dr. Norma G. Sanchez

E-Mail Website
Guest Editor

CNRS. International School D. Chalonge—Hector de Vega, 75014 Paris, France
Interests: cosmology; quantum physics; quantum space–time black holes; gravitational physics; fundamental physics; theoretical astrophysics; theoretical physics; new quantum physical systems; new quantum information systems
Special Issues, Collections and Topics in MDPI journals

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.

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

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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.

Please visit the Instructions for Authors page before submitting a manuscript. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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 (11 papers)

Download All Papers

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

Jump to: Review

38 pages, 1910 KiB

Open AccessArticle

Warm Dark Matter Galaxies with Central Supermassive Black Holes

by Hector J. de Vega and Norma G. Sanchez

Universe 2022, 8(3), 154; https://doi.org/10.3390/universe8030154 - 28 Feb 2022

Cited by 8 | Viewed by 2173

Abstract

We generalize the Thomas–Fermi approach to galaxy structure to include central supermassive black holes and find, self-consistently and non-linearly, the gravitational potential of the galaxy plus the central black hole (BH) system. This approach naturally incorporates the quantum pressure of the fermionic warm dark matter (WDM) particles and shows its full power and clearness in the presence of supermassive black holes. We find the main galaxy and central black hole magnitudes as the halo radius

r_{h}

, halo mass

M_{h}

, black hole mass

M_{B H}

, velocity dispersion

σ

, and phase space density, with their realistic astrophysical values, masses and sizes over a wide galaxy range. The supermassive black hole masses arise naturally in this framework. Our extensive numerical calculations and detailed analytic resolution of the Thomas–Fermi equations show that in the presence of the central BH, both DM regimes—classical (Boltzmann dilute) and quantum (compact)—do necessarily co-exist generically in any galaxy, from the smaller and compact galaxies to the largest ones. The ratio

R (r)

of the particle wavelength to the average interparticle distance shows consistently that the transition,

R ≃ 1

, from the quantum to the classical region occurs precisely at the same point

r_{A}

where the chemical potential vanishes. A novel halo structure with three regions shows up: in the vicinity of the BH, WDM is always quantum in a small compact core of radius

r_{A}

and nearly constant density; in the region

r_{A} < r < r_{i}

until the BH influence radius

r_{i}

, WDM is less compact and exhibits a clear classical Boltzmann-like behavior; for

r > r_{i}

, the WDM gravity potential dominates, and the known halo galaxy shows up with its astrophysical size. DM is a dilute classical gas in this region. As an illustration, three representative families of galaxy plus central BH solutions are found and analyzed: small, medium and large galaxies with realistic supermassive BH masses of

10^{5} M_{⊙}

10^{7} M_{⊙}

and

10^{9} M_{⊙}

, respectively. In the presence of the central BH, we find a minimum galaxy size and mass

M_{h}^{m i n} ≃ 10^{7} M_{⊙}

, larger (

2.2233 \times 10^{3}

times) than the one without BH, and reached at a minimal non-zero temperature

T_{m i n}

. The supermassive BH heats up the DM and prevents it from becoming an exactly degenerate gas at zero temperature. Colder galaxies are smaller, and warmer galaxies are larger. Galaxies with a central black hole have large masses

M_{h} > 10^{7} M_{⊙} > M_{h}^{m i n}

; compact or ultracompact dwarf galaxies in the range

10^{4} M_{⊙} < M_{h} < 10^{7} M_{⊙}

cannot harbor central BHs. We find novel scaling relations

M_{B H} = D M_{h}^{\frac{3}{8}}

and

r_{h} = C M_{B H}^{\frac{4}{3}}

, and show that the DM galaxy scaling relations

M_{h} = b Σ_{0} r_{h}^{2}

and

M_{h} = a {σ_{h}}^{4} / Σ_{0}

hold too in the presence of the central BH,

Σ_{0}

being the constant surface density scale over a wide galaxy range. The galaxy equation of state is derived: pressure

P (r)

takes huge values in the BH vicinity region and then sharply decreases entering the classical region, following consistently a self-gravitating perfect gas

P (r) = σ^{2} ρ (r)

behavior. Full article

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

► Show Figures

Figure 1

13 pages, 306 KiB

Open AccessArticle

Star and Black Hole Formation at High Redshift

by Peter L. Biermann

Universe 2022, 8(3), 146; https://doi.org/10.3390/universe8030146 - 25 Feb 2022

Viewed by 1561

Abstract

Evidence for dark matter (DM) was originally discovered in 1933 by Zwicky (Zwicky 1933, 1937), and has defied all explanations since then. The original discovery was based on the motions of galaxies in clusters of galaxies. The MicroWave Back Ground (MWBG) observations by the Planck mission and other satellites give definitive numbers. Galaxy correlations give results down to small galaxies, which match theoretical expectations. Here we focus on a few interesting aspects, that may allow to determine the nature of dark matter: (1) Ultra Faint Dwarf (UFD) galaxies, that represent the oldest galaxies known. UFDs are almost devoid of baryonic matter. (2) Calculations show that there can be super-sonic flow of baryonic matter. It follows that there are ubiquitous shockwaves; commonly oblique they generate vorticity. (3) Early virialized clumps, mini-halos, have a density that is consistent with the density implied by Super Massive Black Holes (SMBHs) today, if we assume that SMBHs grow by merging, akin to the Press & Schechter (1974) picture for galaxies. This implies that the oldest SMBHs observed today give powerful constraints on the very early phases. Full article

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

7 pages, 526 KiB

Open AccessFeature PaperArticle

Impact of Warm Dark Matter on the Cosmic Neutrino Background Anisotropies

by Christopher G. Tully and Gemma Zhang

Universe 2022, 8(2), 118; https://doi.org/10.3390/universe8020118 - 12 Feb 2022

Cited by 3 | Viewed by 1806

Abstract

The Cosmic Neutrino Background (C

ν

B) anisotropies for massive neutrinos are a unique probe of large-scale structure formation. The redshift-distance measure is completely different for massive neutrinos as compared to electromagnetic radiation. The C

ν

B anisotropies in massive neutrinos grow in [...] Read more.

The Cosmic Neutrino Background (C

ν

ν

B anisotropies in massive neutrinos grow in response to non-relativistic motion in gravitational potentials seeded by relatively high k-modes. Differences in the early phases of large-scale structure formation in warm dark matter (WDM) versus cold dark matter (CDM) cosmologies have an impact on the magnitude of the C

ν

B anisotropies for contributions to the angular power spectrum that peak at high k-modes. We take the examples of WDM consisting of 2, 3, or 7 keV sterile neutrinos and show that the C

ν

B anisotropies for 0.05 eV neutrinos drop off at high-l multipole moment in the angular power spectrum relative to CDM. At the same angular scales that one can observe baryonic acoustical oscillations in the CMB, the C

ν

B anisotropies begin to become sensitive to differences in WDM and CDM cosmologies. The precision measurement of high-l multipoles in the C

ν

B neutrino sky map is a potential possibility for the PTOLEMY experiment with thin film targets of spin-polarized atomic tritium superfluid that exhibit significant quantum liquid amplification for non-relativistic relic neutrino capture. Full article

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

► Show Figures

Figure 1

14 pages, 972 KiB

Open AccessArticle

Warm Dark Matter from Higher-Dimensional Gauge Theories

by Sinziana Paduroiu, Michael Rios, Alessio Marrani and David Chester

Universe 2021, 7(12), 462; https://doi.org/10.3390/universe7120462 - 27 Nov 2021

Cited by 1 | Viewed by 1992

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 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

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

► Show Figures

Figure 1

6 pages, 239 KiB

Open AccessCommunication

Nuclear Matter in 1 + 1 Dimensions

by Robert D. Pisarski, Marton Lajer, Alexei M. Tsvelik and Robert M. Konik

Universe 2021, 7(11), 411; https://doi.org/10.3390/universe7110411 - 29 Oct 2021

Viewed by 1116

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.

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

20 pages, 7180 KiB

Open AccessArticle

The Epoch of Reionization in Warm Dark Matter Scenarios

by Massimiliano Romanello, Nicola Menci and Marco Castellano

Universe 2021, 7(10), 365; https://doi.org/10.3390/universe7100365 - 29 Sep 2021

Cited by 6 | Viewed by 1957

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 cosmologies. We retrace the ionization history of intergalactic medium with hot stellar emission only, exploiting fixed and variable photons escape fraction models (

f_{e s c}

). For each cosmology, we find an upper limit to fixed

f_{e s c}

, 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

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

► Show Figures

Figure 1

20 pages, 1680 KiB

Open AccessArticle

Axion–Sterile Neutrino Dark Matter

by Alberto Salvio and Simone Scollo

Universe 2021, 7(10), 354; https://doi.org/10.3390/universe7100354 - 23 Sep 2021

Cited by 6 | Viewed by 1778

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 inflation (satisfying all current observational bounds). We perform here a general analysis of dark matter (DM) in such a model, which we call the

a ν

MSM. 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

a ν

MSM. 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

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

► Show Figures

Figure 1

19 pages, 654 KiB

Open AccessArticle

New Bounds for the Mass of Warm Dark Matter Particles Using Results from Fermionic King Model

by Luisberis Velazquez

Universe 2021, 7(8), 308; https://doi.org/10.3390/universe7080308 - 20 Aug 2021

Cited by 3 | Viewed by 1568

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) 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

M_{c} = {(ℏ c / G)}^{3 / 2} m^{- 2} ≃ 10^{12} M_{⊙}

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

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

► Show Figures

Figure 1

29 pages, 476 KiB

Open AccessArticle

Sterile Neutrinos as Dark Matter: Alternative Production Mechanisms in the Early Universe

by Daniel Boyanovsky

Universe 2021, 7(8), 264; https://doi.org/10.3390/universe7080264 - 25 Jul 2021

Cited by 2 | Viewed by 1807

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 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

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

► Show Figures

Figure 1

Review

Jump to: Research

29 pages, 3575 KiB

Open AccessReview

Warm Dark Matter in Simulations

by Sinziana Paduroiu

Universe 2022, 8(2), 76; https://doi.org/10.3390/universe8020076 - 27 Jan 2022

Cited by 7 | Viewed by 2349

Abstract

In recent years, warm dark matter models have been studied as a viable alternative to the cold dark matter models. The warm dark matter particle properties are expected to imprint distinct signatures on the structure formation at both large and small scales and there have been many attempts to study these properties with numerical simulations. In this paper, we review and update on warm dark matter simulation studies from the past two decades and their most significant results: structure formation mechanisms, halos evolution, sizes and distribution, and internal structure properties. We discuss the theoretical assumptions and the limitations of the methods employed. In this context, several controversial claims are scrutinized in the attempt to clarify these confusing and sometimes even contradictory conclusions in the numerical simulation literature. We address the circumstances in which a promising keV dark matter candidate should be properly treated in the simulations. Full article

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

► Show Figures

Figure 1

45 pages, 5878 KiB

Open AccessReview

Fundamental Properties of the Dark and the Luminous Matter from the Low Surface Brightness Discs

by Paolo Salucci and Chiara di Paolo

Universe 2021, 7(9), 344; https://doi.org/10.3390/universe7090344 - 13 Sep 2021

Cited by 3 | Viewed by 2357

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 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

g_{b}

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

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

► Show Figures

Journal Menu

Journal Browser

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

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (11 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI