Dark Matter distribution in the Milky Way: microlensing and dynamical constraints (1107.5810v2)

Abstract: We show that current microlensing and dynamical observations of the Galaxy permit to set interesting constraints on the Dark Matter local density and profile slope towards the galactic centre. Assuming state-of-the-art models for the distribution of baryons in the Galaxy, we find that the most commonly discussed Dark Matter profiles (viz. Navarro-Frenk-White and Einasto) are consistent with microlensing and dynamical observations, while extreme adiabatically compressed profiles are robustly ruled out. When a baryonic model that also includes a description of the gas is adopted, our analysis provides a determination of the local Dark Matter density, \rho_0=0.20-0.56 GeV/cm^3 at 1\sigma, that is found to be compatible with estimates in the literature based on different techniques.

• The paper integrates microlensing data with dynamical measurements to validate NFW and Einasto dark matter profiles aligned with the Milky Way’s rotation curve.
• It determines the local dark matter density to be between 0.20 and 0.56 GeV/cm³, consistent with other observational methods.
• The study rules out extreme adiabatically compressed profiles and highlights the need for high-resolution simulations incorporating baryonic effects.

Analysis of Dark Matter Distribution in the Milky Way Using Microlensing and Dynamical Constraints

The paper "Dark Matter distribution in the Milky Way: microlensing and dynamical constraints" by Iocco, Pato, Bertone, and Jetzer presents a comprehensive examination of the Dark Matter (DM) distribution within the Milky Way, leveraging current advancements in microlensing observations and dynamical measurements. The work seeks to address the challenges inherent in accurately determining the galactic DM profile, a crucial aspect for understanding both galactic formation and the interpretation of direct and indirect DM detection experiments.

The authors employ widely-adopted DM profiles—specifically the Navarro-Frenk-White (NFW) and Einasto models—to reconcile DM simulations with observational constraints derived from microlensing and the galaxy's rotation curve. A key finding of their paper is that NFW and Einasto profiles are consistent with microlensing and dynamical observations, providing no evidence against cuspy DM profiles that are often predicted by cosmological simulations under the Cold Dark Matter paradigm. However, they effectively rule out more extreme adiabatically compressed profiles, which predict a steeper rise in DM density towards the galactic center.

The paper presents a robust analysis beginning with the normalization of several baryonic models to match the optical depth derived from MACHO observations towards the galactic bulge. These models are then used to calculate the expected contribution of baryonic mass to the rotation curve, allowing the authors to isolate the DM component's influence. This method serves as a crucial test for the shape and density of the inner DM halo.

Quantitatively, the authors determine the local DM density, $\rho_0$, is within the range of $0.20-0.56\textrm{ GeV/cm}^3$ at a $1\sigma$ confidence level. This result aligns with values obtained by other studies employing different methodologies, suggesting robust inter-method consistency. Such constraints underscore the efficacy of using a combination of microlensing and dynamical data to infer DM properties, providing a benchmark for ongoing and future simulations and observations.

The implications of this research are significant for the broader astrophysical community, particularly in refining the models of DM distribution that underpin the analysis of potential DM detection signals. Additionally, the paper highlights the need for more precise simulations that include baryonic processes to produce a more accurate depiction of DM dynamics that align with the wealth of observational data available.

Future prospects in this domain include the integration of high-resolution numerical simulations with multi-wavelength astronomical data to further clarify the role of baryons in shaping the DM halo. Furthermore, advancements in observational techniques and the potential discovery of new gravitational lenses could enhance the precision of the microlensing optical depth measurement and thus refine the constraints on the DM profile.

Overall, this paper contributes vitally to the understanding of DM in the Milky Way, illustrating a rigorous approach where observational constraints are methodically employed to verify theoretical models. This fusion of observational astronomy and theoretical physics exemplifies the iterative process necessary for advancing knowledge of galactic structure and cosmology.