Mass of milky way
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Mass of the Milky Way: Current Estimates and Methods
Introduction to Milky Way Mass Estimation
The mass of the Milky Way galaxy is a fundamental parameter in astrophysics, influencing our understanding of galaxy formation, dynamics, and cosmology. Despite extensive research, the exact mass remains uncertain, with estimates varying significantly due to different methodologies and data sets.
Methods of Estimating Milky Way Mass
Dynamical Tracers and Bayesian Models
One common approach to estimating the Milky Way's mass involves using dynamical tracers such as halo stars, globular clusters, and satellite galaxies. These tracers provide kinematic data that can be analyzed using hierarchical Bayesian models. For instance, the H3 survey and Gaia EDR3 data have been used to infer the mass distribution of the Milky Way halo, resulting in a median mass within 100 kpc of approximately (0.69 \times 10^{12} M_\odot) and a virial mass of (1.08 \times 10^{12} M_\odot)2.
Parametrized Mass Models
Another method involves fitting parametrized mass models to observational constraints. This approach integrates photometric and kinematic data with theoretical expectations to create a best-fitting model. Recent studies using this method have estimated the Milky Way's virial mass to be around (1.26 \times 10^{12} M_\odot)3.
Satellite Dynamics
The dynamics of Milky Way satellites also provide valuable insights. By comparing the dynamics of these satellites to those in cosmological simulations, researchers have estimated the Milky Way's mass to be approximately (1.17 \times 10^{12} M_\odot)4.
Rotation Curve Analysis
The analysis of the Milky Way's rotation curve, particularly using data from Gaia DR2, has been another effective method. This approach considers the contraction of the dark matter halo due to baryonic matter, leading to an inferred total mass of about (1.08 \times 10^{12} M_\odot)6.
Key Findings and Consensus
Total Mass Estimates
Despite the variety of methods, recent studies converge on a total mass estimate for the Milky Way in the range of (1.0 \times 10^{12} M_\odot) to (1.3 \times 10^{12} M_\odot)1 2 3 4 6. This range accounts for different assumptions and data sets, highlighting the robustness of these estimates.
Inner Mass Distribution
The mass within the inner 20 kpc of the Milky Way has been estimated to be around (1.91 \times 10^{11} M_\odot), with a significant portion attributed to dark matter10. This inner mass distribution is crucial for understanding the galaxy's dynamics and the role of dark matter.
Dark Matter Halo Characteristics
Studies have also focused on the characteristics of the Milky Way's dark matter halo. The density profile and concentration parameters are essential for modeling the galaxy's gravitational potential. For example, the dark matter density at the Solar position has been estimated to be around (0.33 , \text{GeV cm}^{-3})6.
Conclusion
The mass of the Milky Way remains a topic of active research, with estimates converging around (1.0 \times 10^{12} M_\odot) to (1.3 \times 10^{12} M_\odot). Various methods, including dynamical tracers, parametrized models, satellite dynamics, and rotation curve analysis, contribute to this consensus. Future observations and improved models will continue to refine these estimates, enhancing our understanding of the Milky Way and its place in the cosmos.
Sources and full results
Most relevant research papers on this topic
The mass distribution and gravitational potential of the Milky Way
The Milky Way has a total stellar mass of (54.3 5.7) 109 M, a total virial mass of (1.30 0.30) 1012M, and a local dark-matter density of 0.40 0.04 GeV cm-3, with most
Highly CitedThe Mass of the Milky Way from the H3 Survey
The H3 survey and Gaia EDR3 data suggest a median mass of 0.690.04+0.051012M for the Milky Way, with sensitivity to substructure limiting our precision to 15%.
Mass models of the Milky Way
The mass distribution of the Milky Way remains very uncertain, but our method provides a best-fitting model for dynamical modeling.
Highly CitedThe mass of the Milky Way from satellite dynamics
The Milky Way's mass can be inferred from satellite dynamics, with an inner dark matter mass fraction of 0.12, and a halo concentration of 10.9+2.6-2.0$.
Highly CitedMass models of the Milky Way
The mass distribution of the Milky Way remains uncertain, with the halo's influence affecting the structure of the best-fitting model and questioning the flat rotation curves theory.
Highly CitedThe milky way total mass profile as inferred from Gaia DR2
The Milky Way's mass profile is best fit by a contracted NFW halo model, which accounts for baryon contraction and increases the enclosed dark matter halo mass by factors of 1.3, 2, and 4 at radial distances of 20, 8, and 1 kpc.
Highly CitedThe Masses of the Milky Way and Andromeda galaxies
The mass of the Milky Way Galaxy within 300 kpc is M300 = 0.9 0.3, and for M31, M31 = 0.9 0.3.
Highly CitedMass Models of the Milky Way and Estimation of Its Mass from the Gaia DR3 Data Set
The DMD model is comparable in accuracy to the NFW and MOND models, and fits the data better at large radii, while the NFW model has a lower virial mass.
The Mass of the Milky Way: Limits from a newly assembled set of halo objects
The most likely total mass of the Milky Way is 2:5 +0:5 1:0 10 12 M, with the mass estimate largely influenced by several high-velocity objects and a flat rotation curve.
Highly CitedMass and shape of the Milky Way’s dark matter halo with globular clusters from Gaia and Hubble
The Milky Way's inner dark matter halo has a mass of 1.370.17+0.181011 M, with a density axis ratio of 1.30 0.25, and a disc-like component that closely resembles the Galactic thick disc.
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