A Review on the Scalar Field/ Bose-Einstein Condensate Dark Matter Model (1302.0903v1)

Abstract: We review the work done so far aimed at modeling in an alternative way the dark matter in the Universe: the scalar field/ Bose-Einstein condensate dark matter (SFDM/BEC) model. We discuss a number of important achievements and characteristics of the model. We also describe some of our most recent results and predictions of the model compared to those of the standard model of $\Lambda$CDM.

• The paper demonstrates that the SFDM/BEC model better accounts for galactic density profiles and structure formation than conventional CDM models.
• Numerical simulations and Ursa Minor analyses indicate an ultra-light boson mass near 10⁻²² eV is key to aligning theoretical predictions with observed galactic features.
• Perturbative analyses reveal accelerated cosmic structure growth, underscoring the model’s potential to redefine our understanding of dark matter dynamics.

Overview of the Scalar Field/Bose-Einstein Condensate Dark Matter Model

The paper "A Review on the Scalar Field/Bose-Einstein Condensate Dark Matter Model" provides a comprehensive analysis of an alternative dark matter model that is distinct from the conventional $\Lambda$CDM framework. The Scalar Field/Bose-Einstein Condensate (SFDM/BEC) model is posited as a possible candidate to address discrepancies observed at galactic scales that are not adequately explained by Cold Dark Matter (CDM) models. In this model, dark matter (DM) is considered to be composed of bosonic particles, characterized by an ultra-light scalar field $\Phi$, which condenses to form galactic halos.

Key Results and Claims

1. Galactic Structure Formation: The SFDM/BEC model offers a different cosmological evolution path where galactic halos form not in a hierarchical manner but at the same cosmic time, which may explain common structural properties shared by galaxies. Numerical simulations indicate that SFDM/BEC could better fit the density profiles of dwarf and low surface brightness galaxies compared to CDM simulations.
2. Mass Constraints: Research, including analysis of the Ursa Minor dwarf galaxy, suggests that DM halos modeled as SFDM/BEC can provide constraints on the boson mass, estimating a range around $m_{\phi} \sim 10^{-22}$ eV required to maintain structural features observed in globular clusters like Fornax.
3. Perturbation Growth: Perturbative analyses show accelerated structure formation in SFDM/BEC models due to the quantum properties of the scalar field. The evolution of perturbations within these models displays promising alignment with observational data, potentially allowing early formation of structures at redshifts higher than anticipated in $\Lambda$CDM scenarios.
4. Numerical Simulations: Extensive simulations explore the gravitational collapse within SFDM/BEC models. Findings indicate a qualitative fit to core density profiles and galactic rotational curves, which conflicts with cusp-like predictions from CDM models.
5. Potential and Equations: The SFDM/BEC model employs a dynamic scalar field with various potential designs, including the $V(\Phi)=m^2\Phi^2/2$ form, which recreates cosmological behaviors akin to $\Lambda$CDM while offering a method for mitigating gravitational collapse perpetuated through repulsive self-interactions.

Implications and Future Directions

The SFDM/BEC model offers a plausible alternative to traditional dark matter theories, especially in explaining the smoothness and size of core densities within galaxies, contrasting sharply with $\Lambda$CDM’s envisaged cusps. Continued development in theoretical models that simulate the quantum dynamics of the scalar field could further articulate its efficacy in addressing large-scale structure motivations. However, critical questions remain, particularly regarding transparency over baryonic physics and the formation dynamics surrounding black holes which may threaten SFDM persistence in halo regions.

Practical Relevance

Practically, greater exploration and precision in modeling could substantiate SFDM/BEC phenomena alongside technological advances in astronomical observations. These can reevaluate established data for early galaxy formation, potentially shifting the dark matter paradigm. The inherent prediction of core density profiles offers a testable hypothesis against high-resolution data, demanding rigorous scrutiny of both model assumptions and empirical findings.

In conclusion, the SFDM/BEC model carries theoretical potential to enrich and possibly redefine our understanding of cosmic structure formation at scales untapped by current models. Further interdisciplinary research bridging quantum field theory and astrophysics is essential to validate this approach comprehensively. The paper emphasizes that novel constraints and observations could substantially retain this model as a credible, alternative dark matter hypothesis.