Cosmic Structure as the Quantum Interference of a Coherent Dark Wave (1406.6586v1)

Abstract: The conventional cold, particle interpretation of dark matter (CDM) still lacks laboratory support and struggles with the basic properties of common dwarf galaxies, which have surprisingly uniform central masses and shallow density profiles. In contrast, galaxies predicted by CDM extend to much lower masses, with steeper, singular profiles. This tension motivates cold, wavelike dark matter ($\psi$DM) composed of a non-relativistic Bose-Einstein condensate, so the uncertainty principle counters gravity below a Jeans scale. Here we achieve the first cosmological simulations of this quantum state at unprecedentedly high resolution capable of resolving dwarf galaxies, with only one free parameter, $\bf{m_B}$, the boson mass. We demonstrate the large scale structure of this $\psi$DM simulation is indistinguishable from CDM, as desired, but differs radically inside galaxies. Connected filaments and collapsed haloes form a large interference network, with gravitationally self-bound solitonic cores inside every galaxy surrounded by extended haloes of fluctuating density granules. These results allow us to determine $\bf{m_B=(8.1^{+1.6}_{-1.7})\times 10^{-23}~eV}$ using stellar phase-space distributions in dwarf spheroidal galaxies. Denser, more massive solitons are predicted for Milky Way sized galaxies, providing a substantial seed to help explain early spheroid formation. Suppression of small structures means the onset of galaxy formation for $\psi$DM is substantially delayed relative to CDM, appearing at $\bf{z\lesssim 13}$ in our simulations.

• The paper demonstrates that modeling dark matter as a coherent Bose-Einstein condensate addresses discrepancies in small-galaxy structure predictions.
• The paper employs adaptive-mesh-refinement and GPU acceleration to achieve unprecedented resolution in simulating quantum effects in galactic formations.
• The paper infers a boson mass of approximately 8.1×10⁻²³ eV, revealing solitonic cores that challenge conventional cold dark matter profiles.

Analysis of Cosmic Structure as Quantum Interference in a Coherent Dark Wave

The paper presents a comprehensive paper on the behavior and characteristics of a hypothetical model for dark matter, termed as cold, wavelike dark matter ({\psiDM}), which is postulated to form a Bose-Einstein condensate. This model is contrasted with the more conventional cold dark matter (CDM) interpretation that consists of non-relativistic particles. The authors leverage cosmological simulations with high resolution to examine how this {\psiDM} can influence galactic structures differently than CDM.

The paper addresses a particular set of problems associated with standard CDM models, specifically the model's inability to predict some observable characteristics of small galaxies, such as dwarf spheroidals. In conventional CDM frameworks, these galaxies manifest steeper, singular profiles, contrary to empirical observations which reveal uniform central masses and shallower profiles. This discrepancy propels the exploration of {\psiDM}, where principles like the uncertainty principle play a significant role in modulating gravitational influences on a cosmological scale.

Methodological Insights

The authors employ cosmological simulations of unprecedented resolution, a critical step in modeling the behavior of {\psiDM} accurately. The focus is on small-scale structures where the quantum nature of this model can diverge from that of CDM. By assuming a single free parameter, the boson mass $m_B$, the authors place emphasis on evaluating the {\psiDM} cosmological simulations against empirical data, particularly the large-scale structures which remain indistinguishable from those predicted by CDM, ensuring alignment with existing successful frameworks.

The exemplary method of using adaptive-mesh-refinement (AMR) along with GPU acceleration is crucial here, providing enhanced computational efficiency required to handle the temporal and spatial resolutions needed for these simulations.

Results and Observations

The simulations reveal distinct structural formations within galaxies that {\psiDM} would engender. Key among these are solitonic cores found within every galaxy, surrounded by extended halos of fluctuating density granules. Notably, these solitons offer a gravitational self-bound profile, contrastive to the cuspy profiles of CDM predictions. The derived boson mass parameter $m_B=(8.1^{+1.6}_{-1.7})\times 10^{-23}~eV$ is inferred through correlation with existing stellar phase-space distributions in dwarf spheroidal galaxies, indicating a coherent, albeit radically different approach to cosmic structuring.

The suppression of small-scale structures in the {\psiDM} framework leads to a delayed onset of galaxy formation compared to CDM models, suggesting an observable impact in early universe cosmology where formation events would begin notably later.

Implications and Future Directions

The impact of these findings rests largely in providing an alternative perspective to dark matter characterizations that are more in tune with observed galactic phenomena. The presence of solitons offers substantial insights into potential seed forms assisting early spheroidal formations, a challenge for the orthodox CDM framework. Moreover, the quantization effects brought forth through {\psiDM} hint at exciting possibilities for understanding cosmic structures at both cosmological and galactic scales.

Looking ahead, this research serves as a gateway to exploring modifications in galactic evolution narratives, especially in high-redshift contexts where observational albums can starkly contrast. Continued exploration may include developing simulations that incorporate baryonic matter to facilitate a nuanced understanding of how baryons interact with these quantum forms of dark matter, aiming to produce testable rotational curves.

The paper succeeds in challenging existing paradigms and offers a robust foundation for re-examining dark matter's role in shaping the universe, pushing the boundaries of conventional astrophysical models with test propositions and empirically grounded results.