2016MNRAS.463.1865D -
Mon. Not. R. Astron. Soc., 463, 1865-1880 (2016/December-1)
Understanding the internal dynamics of elliptical galaxies without non-baryonic dark matter.
DABRINGHAUSEN J., KROUPA P., FAMAEY B. and FELLHAUER M.
Abstract (from CDS):
Assuming virial equilibrium and Newtonian dynamics, low-mass early-type galaxies have larger velocity dispersions than expected from the amount of baryons they contain. The conventional interpretation of this finding is that their dynamics is dominated by non-baryonic matter. However, there is also strong evidence that many low-mass early-type galaxies formed as tidal dwarf galaxies, which would contain almost no dark matter. Using an extensive catalogue of early-type galaxies, we therefore discuss how the internal dynamics of early-type galaxies in general can be understood by replacing the assumption of non-baryonic dark matter with two alternative assumptions. The first assumption is that Milgromian dynamics (i.e., MOND) is valid, which changes the effective gravitational force in the weak-field limit. The second assumption is that binary stars affect the observed line-of-sight velocity dispersions. Some moderate discrepancies between observed and predicted velocity dispersions remain also when these effects are implemented. Nevertheless, the observed velocity dispersions in early-type galaxies can then easily be explained without invoking the presence of non-baryonic dark matter in them, but with already documented variations of the galaxy-wide stellar initial mass function and non-equilibrium dynamics in some of the low-mass early-type galaxies.
Abstract Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
galaxies: dwarf - galaxies: elliptical and lenticular, CD - galaxies: kinematics and dynamics - galaxies: kinematics and dynamics
Simbad objects:
13
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