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Ultra-light bosonic dark matter (ULDM) is an interesting and promising dark matter candidate. While the wave-like nature of ULDM has been widely studied in the literature, we explore another distinctive feature of ULDM as Bose-Einstein…
Wave dark matter ($\psi$DM) predicts a compact soliton core and a granular halo in every galaxy. This work presents the first simulation study of an elliptical galaxy by including both stars and $\psi$DM, focusing on the systematic changes…
A distinctive feature of ultralight bosonic dark matter is its ability to form a Bose-Einstein condensate with a dense, stationary configuration at the center of galactic halos. In this work, we investigate the internal dynamics of such…
The effect of gravitational darkening on models of the thermal structure of Be star disks is systematically studied for a wide range of Be star spectral types and rotation rates. Gravitational darkening causes a reduction of the stellar…
Our results demonstrate that vortex lines in Bose-Einstein Condensate Dark Matter (BECDM) can act as gravitational seeds that induce the condensation of baryonic matter, leading to localized gas accumulation even in the absence of imposed…
N-body simulations and analytical calculations of the gravitational collapse in an expanding universe predict that halos should form with a diverging inner density profile, the cusp. There are some observational indications that the dark…
This is a brief review on the history of the Bose-Einstein condensate (BEC) or boson star model of galactic dark matter halos, where ultra-light scalar dark matter particles condense in a single BEC quantum state. The halos can be described…
In the present work, the Brans-Dicke (BD) theory of gravity is taken as a possible theory of k-essence. Then starting with the (already known) Brans-Dicke-Schwarzschild solution which can represent the gravitationally bound static…
Observations show that about the 20% of the Universe is composed by invisible (dark) matter (DM), for which many candidates have been proposed. In particular, the anomalous behavior of rotational curves of galaxies (i.e. the flattening at…
Coupling the dark matter (DM) and baryonic components in galaxies via dynamical friction (by allowing the latter to be clumpy) leads to energy input into the DM. The resulting expanding tendency in the DM component overcomes the competing…
There has been considerable interest in the last several years in support of the idea that galaxies and clusters could have highly condensed cores of dark matter (DM) within their central regions. In particular, it has been suggested that…
Decoherence describes the tendency of quantum sub-systems to dynamically lose their quantum character. This happens when the quantum sub-system of interest interacts and becomes entangled with an environment that is traced out. For ordinary…
Galaxies and their dark-matter halos are commonly presupposed to spin. But it is an open question how this spin manifests in halos and soliton cores made of scalar dark matter (SDM, including fuzzy/wave/ultralight-axion dark matter). One…
The effects of gravitational darkening on the thermal structure of Be star disks of differing densities are systematically examined. Gravitational darkening is the decrease of the effective temperature near the equator and the corresponding…
We assume that the galactical dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate \cite{pir12}, can present topological defects, namely domain walls, arising as the dark soliton solution for the…
We develop a model of Bose-Einstein condensate dark matter halos with a solitonic core and an isothermal atmosphere based on a generalized Gross-Pitaevskii-Poisson equation [P.H. Chavanis, Eur. Phys. J. Plus 132, 248 (2017)]. This equation…
Scalar Field Dark Matter (SFDM), comprised of ultralight ($\gtrsim 10^{-22}$ eV) bosons, is distinguished from massive ($\gtrsim$ GeV), collisionless Cold Dark Matter (CDM) by its novel structure-formation dynamics as Bose-Einstein…
The observation of flat rotation curves in asymptotic region of galaxies implies that the dark matter density profile decreases exponentially with the gravitational potential in this region. It is curious that this behavior is identical to…
Considering the existence of old neutron stars puts strong limits on the dark matter/nucleon cross section for bosonic asymmetric dark matter. Key to these bounds is formation of a Bose-Einstein condensate (BEC) of the asymmetric dark…
The phase diagrams of ultralight dark matter (DM), modeled as a self-gravitating Bose-Einstein condensate with axionlike interaction, are studied. We classify stable, metastable, and unstable DM states over a wide range of condensate wave…