• Corpus ID: 219176629

The Milky Way Mass Constrained by Its Hot Gaseous Halo

@article{Guo2020TheMW,
  title={The Milky Way Mass Constrained by Its Hot Gaseous Halo},
  author={Fulai Guo and Ruiyu Zhang and Xia Fang},
  journal={arXiv: Astrophysics of Galaxies},
  year={2020}
}

• Fulai Guo, Ruiyu Zhang, X. Fang
• Published 1 June 2020
• Physics
• arXiv: Astrophysics of Galaxies

The Milky Way (MW) mass $M_{\rm vir}$ is a fundamental quantity in astronomy. Although it has been measured extensively, it is still uncertain to more than a factor of two due to limited number or spatial coverage of kinematic tracers. Here we use a novel method to constrain $M_{\rm vir}$ based on the properties of the MW corona. We build a hydrostatic corona model with non-thermal pressure support and a physically-motivated density profile, and derive the temperature distribution, which depends on $M_{\rm vir}$. While the temperature profile decreases substantially with radius, the X-ray-emission-weighted average temperature $T_{\rm em}$ is quite uniform toward different sight lines, consistent with X-ray observations. Using available measurements of $T_{\rm em}$, we find that $M_{\rm vir}$=$1.60^{+1.35}_{-0.41}$ $\times$ $10^{12}$ $M_{\rm sun}$ assuming an Navarro-Frenk-White (NFW) total matter distribution. This estimate is independent of the uncertain total corona mass and the gas temperature at very large radii, and is on the high mass side of current measurements. Adopting a $\beta$ model for the corona density distribution or a total matter distribution contributed by an NFW dark matter distribution and a central cold baryonic matter distribution leads to similar estimates of $M_{\rm vir}$. Non-thermal pressure support, which likely exists in the corona, leads to higher values of $M_{\rm vir}$.