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Dynamics of Groups around Interacting Double Ellipticals: Measuring Dark Matter Haloes

Published online by Cambridge University Press:  12 April 2016

H. Quintana
H. Quintana*
Affiliation:
Astrophysics Group, P. Universidad Católica de Chile

Extract

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Binary galaxies, as binary stars, are important to measure masses, as suggested by Page (1952). Because three orbit parameters are measurable for galaxies at one instant of time, severe uncertainties remain in the orbit and mass determinations. These uncertainties can partly be overcome by statistical studies of selected samples and/or n-body simulations. Close double galaxies (and isolated galaxies) could also be useful to estimate dynamical masses if we can find test particles around them.

Interacting elliptical pairs or dumb-bell galaxies are found with a large range, between 0-1200 km s-1, of relative radial velocities. Standard 2-body orbit calculations, highly uncertain due to projection factors, suggest for the largest velocity differences very large galaxy masses, if the systems are bound and stationary. However, recent n-body simulations model these binaries as galaxies captured from hyperbolic orbits, requiring masses of order a few times 1011M⊙) (Borne et al. 1988), but producing systems that are short lived.

Type
I. Classical Observations of Pairs
Information
International Astronomical Union Colloquium , Volume 124: Paired and Interacting Galaxies , 1990 , pp. 37 - 41
Copyright
Copyright © NASA 1990

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