Joint constraints on the Galactic dark matter halo and Galactic Centre from hypervelocity stars

E. M. Rossi*, T. Marchetti, M. Cacciato, M. Kuiack, R. Sari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


The mass assembly history of the Milky Way can inform both theory of galaxy formation and the underlying cosmological model. Thus, observational constraints on the properties of both its baryonic and dark matter contents are sought. Here, we show that hypervelocity stars (HVSs) can in principle provide such constraints.We model the observed velocity distribution of HVSs, produced by tidal break-up of stellar binaries caused by Sgr A*. Considering a Galactic Centre (GC) binary population consistent with that inferred in more observationally accessible regions, a fit to current HVS data with significance level > 5 per cent can only be obtained if the escape velocity from the GC to 50 kpc is VG ≲ 850 km s-1, regardless of the enclosed mass distribution. When a Navarro, Frenk and White matter density profile for the dark matter halo is assumed, haloes with VG ≲ 850 km s-1 are in agreement with predictions in the ≲ cold dark matter model and a subset of models around M200 ~ 0.5-1.5 × 1012M and rs ≲ 35 kpc can also reproduce Galactic circular velocity data. HVS data alone cannot currently exclude potentials with VG > 850 km s-1. Finally, specific constraints on the halo mass from HVS data are highly dependent on the assumed baryonic mass potentials. This first attempt to simultaneously constrain GC and dark halo properties is primarily hampered by the paucity and quality of data. It nevertheless demonstrates the potential of our method, that may be fully realized with the ESA Gaia mission.

Original languageAmerican English
Pages (from-to)1844-1856
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© 2017 The Authors.


  • Dark matter
  • Galaxy: Centre
  • Galaxy: halo
  • Methods: analytical
  • Stars: kinematics and dynamics


Dive into the research topics of 'Joint constraints on the Galactic dark matter halo and Galactic Centre from hypervelocity stars'. Together they form a unique fingerprint.

Cite this