Revealing turbulent Dark Matter via merging of self-Gravitating condensates (2501.13689v1)

Abstract: Self-gravitating condensates have been proposed as potential candidates for modelling dark matter. In this paper, we numerically investigate the dynamics of dark matter utilizing the merging of self-gravitating condensates. We have used the Gross-Pitaevskii-Poisson model and identified distinct turbulent regimes based on the merging speed of the condensate. As a result of collision, we notice the appearance of various dark soliton-mediated instabilities that finally lead to the turbulent state characterized by Kolmogorov-like turbulence scaling ( \varepsilon_{\mathrm{kin}}^i \sim k^{-5/3} ) in the infrared and ( \varepsilon_{\mathrm{kin}}^i \sim k^{-3} ) in the ultraviolet regions. The compressible spectrum suggests weak-wave turbulence. The turbulent fluctuations in the condensate cease as the vortices formed via soliton decay are expelled to the condensate's periphery, manifested in the transferring of kinetic energy from incompressible and compressible flows to the quantum pressure energy. We also establish the significant role played by the self-gravitating trap in determining the distribution of compressible kinetic energy and the resulting density waves, which differ markedly from those observed in atomic condensates under harmonic confinement. Our study may offer valuable insights into the merging of binary stars and open new avenues for understanding the structure and dynamics of the dark matter through self-gravitating condensate.

• The paper demonstrates that merging self-gravitating condensates modeled by the GPP framework generate turbulent dark matter behavior through interference patterns and soliton formation.
• It reveals key vortex dynamics, including the emergence of a central vortex with circulation doubling from initial vortices and the development of vortex-antivortex pairs.
• It highlights energy transfer among compressible, incompressible, and quantum pressure components, with kinetic energy spectra showing a Kolmogorov-like k^(-5/3) scaling indicative of classical turbulence.

Analysis of Turbulent Dark Matter through Merging Self-Gravitating Condensates

The paper "Revealing Turbulent Dark Matter via Merging of Self-Gravitating Condensates" investigates the dynamics and turbulent behaviors of dark matter, modeled as self-gravitating Bose-Einstein condensates (BECs). Utilizing the Gross-Pitaevskii-Poisson (GPP) framework, the authors explore how colliding condensates result in turbulent states characterized by specific energy cascades. This research provides insights into the nature of dark matter and offers potential clues for understanding cosmological phenomena such as the merging of binary stars and other astrophysical structures.

Methodology and Model

In this paper, self-gravitating condensates are proposed as models for dark matter. The dynamics of these condensates during collisions are explored through numerical simulations employing the GPP equations. The simulations investigate different collisional velocities, with particular interest in velocities below the quasi-elastic limit, where the condensates merge into a single structure. The derived model operates under the assumption that BECs exhibit superfluid behavior when subjected to gravitational interactions.

Main Findings

The outcomes of the merging simulations reveal several significant observations:

1. Interference Patterns and Solitons: Upon collision, interference fringes materialize as a result of phase differences. These fringes evolve into ring solitons, which eventually decay through Snake instabilities into vortex-antivortex pairs.
2. Vortex Formation and Dynamics: The turbulent phenomena are characterized by distinct vortex structures. The persistent central vortex with circulation $s = 2$ emerges from the coalescence of initially present $s = 1$ vortices. The vortices and antivortices formed tend toward the condensate periphery, signifying transient vortex activity.
3. Energy Spectra and Turbulence: The incompressible kinetic energy spectra demonstrate a Kolmogorov-like scaling law, $k^{-5/3}$, characteristic of classical turbulence, for wave numbers corresponding to the intervortex distance. The compressible spectra suggest weak-wave turbulence, highlighting the presence of significant density waves even at cosmological scales.
4. Energy Transfer: The paper highlights energy transfer among different kinetic components—compressible, incompressible, and quantum pressure energy—underscoring the transitions between these states as the condensate evolves post-collision.

Implications and Speculative Outlook

The insights gained from this paper are twofold. Practically, understanding turbulence in dark matter models can inform astrophysical theories related to galactic formation and dynamics, such as galaxy mergers. Theoretically, the research expands the GPP model's applicability beyond typical scenarios, contributing to the broader understanding of dark matter's superfluid characteristics. Additionally, the findings regarding vortex dynamics and energy scaling could have implications for understanding the nature of quantum turbulence and its analogs in cosmic structures.

The exploration of such condensed matter properties in a cosmological setting opens new possibilities for future research directions. Further developments could involve exploring varying initial conditions, external perturbations, or coupling with other cosmological parameters to simulate more intricate dynamics. Additionally, improving observational techniques might make it feasible to detect gravitational wave signatures associated with such turbulent aftermaths, providing empirical support for theories related to self-gravitating BECs and dark matter.

Overall, this paper strengthens the narrative that BECs, when modeled under gravitational self-interaction laws, can exhibit complex behaviors akin to quantum turbulence, thus offering a promising avenue for investigating the enigmatic nature of dark matter.