The escape velocity curve of the Milky Way in Modified Newtonian dynamics

Indranil Banik, Hongsheng Zhao

Research output: Contribution to journalArticlepeer-review

Abstract

We determine the escape velocity from the Milky Way (MW) at a range of Galactocentric radii in the context of Modified Newtonian Dynamics (MOND). Due to its non-linear nature, escape is possible if the MW is considered embedded in a constant external gravitational field (EF) from distant objects. We model this situation using a fully self-consistent method based on a direct solution of the governing equations out to several thousand disk scale lengths. We try out a range of EF strengths and mass models for the MW in an attempt to match the escape velocity measurements of Williams et al. (2017). A reasonable match is found if the EF on the MW is ∼0.03a0, towards the higher end of the range considered. Our models include a hot gas corona surrounding the MW, but our results suggest that this should have a very low mass of ∼2 × 1010M to avoid pushing the escape velocity too high. Our analysis favours a slightly lower baryonic disk mass than the ∼7 × 1010M required to explain its rotation curve in MOND. However, given the uncertainties, MOND is consistent with both the locally measured amplitude of the MW rotation curve and its escape velocity over Galactocentric distances of 8−50 kpc.
Original languageEnglish
Pages (from-to)419-430
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume473
Issue number1
Early online date11 Sept 2017
DOIs
Publication statusPublished - Jan 2018

Keywords

  • Galaxies: groups: individual: Local Group
  • Galaxy: kinematics and dynamics
  • Dark Matter
  • Methods: numerical
  • Methods: data analysis
  • Cosmology: cosmological parameters

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