scholarly journals Jeans Instability of Dissipative Self-Gravitating Bose–Einstein Condensates with Repulsive or Attractive Self-Interaction: Application to Dark Matter

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 226
Author(s):  
Pierre-Henri Chavanis
Keyword(s):  
Dark Matter ◽  
Scattering Length ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Einstein Condensate ◽  
Wave Number ◽  
Arbitrary Form ◽  
Bose Einstein Condensate ◽  
Jeans Instability ◽  
Bose Einstein

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.

scholarly journals Jeans instability and turbulent gravitational collapse of Bose–Einstein condensate dark matter halos

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Tiberiu Harko
Keyword(s):  
Dark Matter ◽  
Gravitational Collapse ◽  
Separation Of Variables ◽  
Einstein Condensate ◽  
Wave Number ◽  
Radial Coordinate ◽  
Dark Matter Halos ◽  
Bose Einstein Condensate ◽  
Jeans Instability ◽  
Bose Einstein

Abstract We consider the Jeans instability and the gravitational collapse of the rotating Bose–Einstein condensate dark matter halos, described by the zero temperature non-relativistic Gross–Pitaevskii equation, with repulsive interparticle interactions. In the Madelung representation of the wave function, the dynamical evolution of the galactic halos is described by the continuity and the hydrodynamic Euler equations, with the condensed dark matter satisfying a polytropic equation of state with index $$n=1$$n=1. By considering small perturbations of the quantum hydrodynamical equations we obtain the dispersion relation and the Jeans wave number, which includes the effects of the vortices (turbulence), of the quantum pressure and of the quantum potential, respectively. The critical scales above which condensate dark matter collapses (the Jeans radius and mass) are discussed in detail. We also investigate the collapse/expansion of rotating condensed dark matter halos, and we find a family of exact semi-analytical solutions of the hydrodynamic evolution equations, derived by using the method of separation of variables. An approximate first order solution of the fluid flow equations is also obtained. The radial coordinate dependent mass, density and velocity profiles of the collapsing/expanding condensate dark matter halos are obtained by using numerical methods.

scholarly journals Testing Bose–Einstein condensate dark matter models with the SPARC galactic rotation curves data

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Maria Crăciun ◽  
Tiberiu Harko
Keyword(s):  
Dark Matter ◽  
Good Description ◽  
Scattering Length ◽  
Einstein Condensate ◽  
Galactic Rotation ◽  
Rotation Curves ◽  
Galactic Rotation Curves ◽  
Bose Einstein Condensate ◽  
Two Parameters ◽  
Bose Einstein

Abstract The nature of one of the fundamental components of the Universe, dark matter, is still unknown. One interesting possibility is that dark matter could exist in the form of a self-interacting Bose–Einstein Condensate (BEC). The fundamental properties of dark matter in this model are determined by two parameters only, the mass and the scattering length of the particle. In the present study we investigate the properties of the galactic rotation curves in the BEC dark matter model, with quadratic self-interaction, by using 173 galaxies from the recently published Spitzer Photomery & Accurate Rotation Curves (SPARC) data. We fit the theoretical predictions of the rotation curves in the slowly rotating BEC models with the SPARC data by using genetic algorithms. We provide an extensive set of figures of the rotation curves, and we obtain estimates of the relevant astrophysical parameters of the BEC dark matter halos (central density, angular velocity and static radius). The density profiles of the dark matter distribution are also obtained. It turns out that the BEC model gives a good description of the SPARC data. The presence of the condensate dark matter could also provide a solution for the core–cusp problem.

scholarly journals Dark Matter as a Non-Relativistic Bose–Einstein Condensate with Massive Gravitons

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 520 ◽  
Author(s):  
Emma Kun ◽  
Zoltán Keresztes ◽  
Saurya Das ◽  
László Á. Gergely
Keyword(s):  
Dark Matter ◽  
Chemical Potential ◽  
Yukawa Potential ◽  
Scattering Length ◽  
Einstein Condensate ◽  
Graviton Mass ◽  
Bose Einstein Condensate ◽  
Upper Limits ◽  
Bose Einstein ◽  
Exponential Disk

We confront a non-relativistic Bose–Einstein Condensate (BEC) model of light bosons interacting gravitationally either through a Newtonian or a Yukawa potential with the observed rotational curves of 12 dwarf galaxies. The baryonic component is modeled as an axisymmetric exponential disk and its characteristics are derived from the surface luminosity profile of the galaxies. The purely baryonic fit is unsatisfactory, hence a dark matter component is clearly needed. The rotational curves of five galaxies could be explained with high confidence level by the BEC model. For these galaxies, we derive: (i) upper limits for the allowed graviton mass; and (ii) constraints on a velocity-type and a density-type quantity characterizing the BEC, both being expressed in terms of the BEC particle mass, scattering length and chemical potential. The upper limit for the graviton mass is of the order of 10 - 26 eV/c2, three orders of magnitude stronger than the limit derived from recent gravitational wave detections.

scholarly journals Two-component axionic dark matter halos

2020 ◽  
Vol 35 (26) ◽  
pp. 2050227 ◽  
Author(s):  
Gennady P. Berman ◽  
Vyacheslav N. Gorshkov ◽  
Vladimir I. Tsifrinovich ◽  
Marco Merkli ◽  
Vladimir V. Tereshchuk
Keyword(s):  
Dark Matter ◽  
Ground State ◽  
Mass Density ◽  
Mean Field ◽  
Einstein Condensate ◽  
Dark Matter Halo ◽  
Bose Einstein Condensate ◽  
Interesting Connection ◽  
Two Component ◽  
Bose Einstein

We consider a two-component dark matter halo (DMH) of a galaxy containing ultra-light axions (ULA) of different mass. The DMH is described as a Bose–Einstein condensate (BEC) in its ground state. In the mean-field (MF) limit, we have derived the integro-differential equations for the spherically symmetrical wave functions of the two DMH components. We studied, numerically, the radial distribution of the mass density of ULA and constructed the parameters which could be used to distinguish between the two- and one-component DMH. We also discuss an interesting connection between the BEC ground state of a one-component DMH and Black Hole temperature and entropy, and Unruh temperature.

scholarly journals Supplying dark energy from scalar field dark matter

2018 ◽  
Vol 27 (09) ◽  
pp. 1850100
Author(s):  
Merab Gogberashvili ◽  
Alexander Sakharov
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gordon Equation ◽  
Einstein Condensate ◽  
Scalar Particles ◽  
Bose Einstein Condensate ◽  
Constant Solution ◽  
Klein Gordon ◽  
Free Parameters ◽  
Bose Einstein

We consider the hypothesis that dark matter (DM) and dark energy (DE) consist of ultra-light self-interacting scalar particles. It is found that the Klein–Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose–Einstein Condensate (BEC), behaving as DM, while the constant solution at supra-galactic scales can explain DE.

scholarly journals DARK MATTER AXIONS

2010 ◽  
Vol 25 (02n03) ◽  
pp. 554-563 ◽  
Author(s):  
P. SIKIVIE
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Cold Dark Matter ◽  
Einstein Condensate ◽  
Dark Matter Halos ◽  
Linear Regime ◽  
Bose Einstein Condensate ◽  
Invisible Axion ◽  
Bose Einstein ◽  
The Universe

The hypothesis of an 'invisible' axion was made by Misha Shifman and others, approximately thirty years ago. It has turned out to be an unusually fruitful idea, crossing boundaries between particle physics, astrophysics and cosmology. An axion with mass of order 10-5 eV (with large uncertainties) is one of the leading candidates for the dark matter of the universe. It was found recently that dark matter axions thermalize and form a Bose-Einstein condensate (BEC). Because they form a BEC, axions differ from ordinary cold dark matter (CDM) in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles. Because there is evidence for these phenomena, unexplained with ordinary CDM, an argument can be made that the dark matter is axions.

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