TY - JOUR
T1 - The escape velocity curve of the Milky Way in Modified Newtonian dynamics
AU - Banik, Indranil
AU - Zhao, Hongsheng
N1 - IB is supported by Science and Technology Facilities Council studentship 1506672.
PY - 2018/1
Y1 - 2018/1
N2 - 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.
AB - 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.
KW - Galaxies: groups: individual: Local Group
KW - Galaxy: kinematics and dynamics
KW - Dark Matter
KW - Methods: numerical
KW - Methods: data analysis
KW - Cosmology: cosmological parameters
UR - https://arxiv.org/abs/1708.03771
UR - https://academic.oup.com/mnras/article/473/1/419/4111174?guestAccessKey=94a4893e-4bbc-4157-8930-2815735b1692
U2 - 10.1093/mnras/stx2350
DO - 10.1093/mnras/stx2350
M3 - Article
SN - 1365-2966
VL - 473
SP - 419
EP - 430
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -