Constraining the Milky Way mass with hypervelocity stars

G. Fragione*, A. Loeb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Although a variety of techniques have been employed for determining the Milky Way dark matter halo mass distribution, the range of allowed masses spans both light and heavy values. Knowing the precise mass of our Galaxy is important for placing the Milky Way in a cosmological ΛCDM context. We show that hypervelocity stars (HVSs) ejected from the center of the Milky Way galaxy can be used to constrain the mass of its dark matter halo. We use the asymmetry in the radial velocity distribution of halo stars due to escaping HVSs, which depends on the halo potential (escape speed) as long as the round trip orbital time is shorter than the stellar lifetime, to discriminate between different models for the Milky Way gravitational potential. Adopting a characteristic HVS travel time of 330 Myr, which corresponds to the average mass of main sequence HVSs, we find that current data favors a mass for the Milky Way in the range (1.2−1.9)×1012M.

Original languageEnglish (US)
Pages (from-to)32-38
Number of pages7
JournalNew Astronomy
StatePublished - Aug 1 2017


  • Galaxy: halo
  • Galaxy: kinematics and dynamics
  • stars: kinematics and dynamics

ASJC Scopus subject areas

  • Instrumentation
  • Astronomy and Astrophysics
  • Space and Planetary Science


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