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Universe
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Dark Matter as a Bose-Einstein Condensate
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Dark Matter as a Bose-Einstein Condensate

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

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 7923

Special Issue Editors

Prof. Dr. Tiberiu Harko

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Guest Editor
1. Astronomical Observatory, 19 Ciresilor Street, 400487 Cluj-Napoca, Romania
2. Department of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Rumania
Interests: general relativity; cosmology; modified theories of gravity; dark matter and dark energy; Bose-Einstein Condensation; high energy astrophysics; stellar structure; mathematical physics; Jacobi stability; nonlinear dynamical systems
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Francisco S. N. Lobo

E-Mail Website
Guest Editor
Institute of Astrophysics and Space Sciences, University of Lisbon, 1749-016 Lisboa, Portugal
Interests: modified gravity; dark energy; cosmology; dark matter; black holes; energy conditions; causal structure of spacetime
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

The existence of dark matter is one of the fundamental assumptions of modern cosmology and astrophysics, and its nature is one of the most important open questions in physics. In fact, after almost a century of intensive study and research, the properties of dark matter remain elusive. Presently, all available information on the dark sector is obtained from the study of its gravitational interactions with astrophysical systems. Despite the intensive experimental effort, no direct detection of dark matter particles has been reported yet.

If dark matter is composed of massive bosons, a Bose–Einstein Condensation process must have occurred during cosmological evolution. Therefore, galactic dark matter may be in the form of a condensate, characterized by a strong self-interaction. Usually, condensate dark matter is described as a quantum fluid satisfying the Gross–Pitaevskii equation. By using the hydrodynamic representation of this equation, one obtains the basic equations describing the physical properties of galactic halos, which allow an in-depth comparison of the theoretical predictions with observations. In particular, much work has been devoted to the fitting of the observed galactic rotation curves with the condensate dark matter model.

Even though the Bose–Einstein Condensation process has been extensively studied, many important questions have yet to be answered. Can we infer the physical state of the dark matter from galactic- and extra-galactic-scale astrophysical observations? What observations may support the existence of a dark matter condensate, and what observations would contradict it? Moreover, we would like to know in what cosmological epoch the condensation process took place. What was the order of the phase transition (crossover), and how long the transition lasted?

It is the goal of this Special Issue to bring together experts from different fields (theoretical physics, astrophysics, cosmology, and even condensed matter) to further investigate, analyze, and develop the idea of dark matter as a Bose–Einstein Condensate. The topics to be covered range from galactic dynamics to the cosmology of the early- and present-day Universe, and novel theoretical ideas and comprehensive comparisons between theory and observations are welcomed. A better understanding of the numerical values of the Bose–Einstein condensation parameters would be very helpful to obtain accurate information on the properties of dark matter. The advances expected from this Special Issue may lead to the development of powerful methods for the observational testing of the predictions of the Bose–Einstein Condensation model on astrophysical and cosmological scales and for the possible confirmation of the existence of condensate dark matter.

Prof. Dr. Tiberiu Harko
Prof. Dr. Francisco S. N. Lobo
Guest Editors

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

  • Dark matter
  • Bose–Einstein Condensation
  • Cosmological phase transitions
  • Observational tests of condensate dark matter

Published Papers (4 papers)

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Research

18 pages, 667 KiB  
Article
Bose–Einstein Condensate Dark Matter That Involves Composites
by Alexandre M. Gavrilik and Andriy V. Nazarenko
Universe 2022, 8(3), 187; https://doi.org/10.3390/universe8030187 - 17 Mar 2022
Cited by 2 | Viewed by 1644
Abstract
Improving the Bose–Einstein condensate model of dark matter through the repulsive three-particle interaction to better reproduce observables such as rotation curves reveals both different thermodynamic phases and few-particle correlations. Using the numerically found solutions of the Gross–Pitaevskii equation for averaging the products of [...] Read more.
Improving the Bose–Einstein condensate model of dark matter through the repulsive three-particle interaction to better reproduce observables such as rotation curves reveals both different thermodynamic phases and few-particle correlations. Using the numerically found solutions of the Gross–Pitaevskii equation for averaging the products of local densities and for calculating thermodynamic functions at zero temperature, it is shown that the few-particle correlations imply a first-order phase transition and are reduced to the product of single-particle averages with a simultaneous increase in pressure, density, and quantum fluctuations. Under given conditions, dark matter exhibits the properties of an ideal gas with an effective temperature determined by quantum fluctuations. Characteristics of oscillations between bound and unbound states of three particles are estimated within a simple random walk approach to qualitatively model the instability of particle complexes. On the other hand, the density-dependent conditions for the formation of composites are analyzed using chemical kinetics without specifying the bonds formed. The obtained results can be extended to the models of multicomponent dark matter consisting of composites formed by particles with a large scattering length. Full article
(This article belongs to the Special Issue Dark Matter as a Bose-Einstein Condensate)
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11 pages, 481 KiB  
Communication
Phases of the Bose–Einstein Condensate Dark Matter Model with Both Two- and Three-Particle Interactions
by Alexandre M. Gavrilik and Andriy V. Nazarenko
Universe 2021, 7(10), 359; https://doi.org/10.3390/universe7100359 - 27 Sep 2021
Cited by 5 | Viewed by 1302
Abstract
In this paper, we further elaborate on the Bose–Einstein condensate (BEC) dark matter model extended in our previous work [Phys. Rev. D 2020, 102, 083510] by the inclusion of sixth-order (or three-particle) repulsive self-interaction term. Herein, our goal is [...] Read more.
In this paper, we further elaborate on the Bose–Einstein condensate (BEC) dark matter model extended in our previous work [Phys. Rev. D 2020, 102, 083510] by the inclusion of sixth-order (or three-particle) repulsive self-interaction term. Herein, our goal is to complete the picture through adding to the model the fourth-order repulsive self-interaction. The results of our analysis confirm the following: while in the previous work the two-phase structure and the possibility of first-order phase transition was established, here we demonstrate that with the two self-interactions involved, the nontrivial phase structure of the enriched model remains intact. For this to hold, we study the conditions which the parameters of the model, including the interaction parameters, should satisfy. As a by-product and in order to provide some illustration, we obtain the rotation curves and the (bipartite) entanglement entropy for the case of a particular dwarf galaxy. Full article
(This article belongs to the Special Issue Dark Matter as a Bose-Einstein Condensate)
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14 pages, 573 KiB  
Article
Supermassive Black Holes from Bose-Einstein Condensed Dark Matter—Or Black and Dark Separation by Angular Momentum
by Masahiro Morikawa
Universe 2021, 7(8), 265; https://doi.org/10.3390/universe7080265 - 26 Jul 2021
Cited by 1 | Viewed by 1575
Abstract
Many supermassive black holes (SMBH) of mass 106∼9M⊙ are observed at the center of each galaxy even in the high redshift (z≈7) Universe. To explain the early formation and the common existence of SMBH, [...] Read more.
Many supermassive black holes (SMBH) of mass 106∼9M⊙ are observed at the center of each galaxy even in the high redshift (z≈7) Universe. To explain the early formation and the common existence of SMBH, we previously proposed the SMBH formation scenario by the gravitational collapse of the coherent dark matter (DM) composed from the Bose-Einstein Condensed (BEC) objects. A difficult problem in this scenario is the inevitable angular momentum which prevents the collapse of BEC. To overcome this difficulty, in this paper, we consider the very early Universe when the BEC-DM acquires its proper angular momentum by the tidal torque mechanism. The balance of the density evolution and the acquisition of the angular momentum determines the mass of the SMBH as well as the mass ratio of BH and the surrounding dark halo (DH). This ratio is calculated as MBH/MDH≈10−3∼−5(Mtot/1012M⊙)−1/2 assuming simple density profiles of the initial DM cloud. This result turns out to be consistent with the observations at z≈0 and z≈6, although the data scatter is large. Thus, the angular momentum determines the separation of black and dark, i.e., SMBH and DH, in the original DM cloud. Full article
(This article belongs to the Special Issue Dark Matter as a Bose-Einstein Condensate)
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54 pages, 1937 KiB  
Article
Jeans Instability of Dissipative Self-Gravitating Bose–Einstein Condensates with Repulsive or Attractive Self-Interaction: Application to Dark Matter
by Pierre-Henri Chavanis
Universe 2020, 6(12), 226; https://doi.org/10.3390/universe6120226 - 27 Nov 2020
Cited by 15 | Viewed by 2168
Abstract
We study the Jeans instability of an infinite homogeneous dissipative self-gravitating Bose–Einstein condensate described by generalized Gross–Pitaevskii–Poisson equations [Chavanis, P.H. Eur. Phys. J. Plus2017, 132, 248]. This problem has applications in relation to the formation of dark matter halos in [...] Read more.
We study the Jeans instability of an infinite homogeneous dissipative self-gravitating Bose–Einstein condensate described by generalized Gross–Pitaevskii–Poisson equations [Chavanis, P.H. Eur. Phys. J. Plus2017, 132, 248]. This problem has applications in relation to the formation of dark matter halos in cosmology. We consider the case of a static and an expanding universe. We take into account an arbitrary form of repulsive or attractive self-interaction between the bosons (an attractive self-interaction being particularly relevant for the axion). We consider both gravitational and hydrodynamical (tachyonic) instabilities and determine the maximum growth rate of the instability and the corresponding wave number. We study how they depend on the scattering length of the bosons (or more generally on the squared speed of sound) and on the friction coefficient. Previously obtained results (notably in the dissipationless case) are recovered in particular limits of our study. Full article
(This article belongs to the Special Issue Dark Matter as a Bose-Einstein Condensate)
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