Merging instability in groups of galaxies with dark matter

Several N-body experiments were performed in order to analyze the importance of smoothly distributed dark matter on the merging processes in groups of galaxies. We simulated groups of galaxies as self-gravitating systems of softened point masses with average intergalactic distance (Dₘ) ranging betwe...

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Detalles Bibliográficos
Autores principales: Navarro, J., Mosconi, M., García-Lambas, D.
Formato: Articulo Comunicacion
Lenguaje:Español
Publicado: 1987
Materias:
Astronomía
Galaxias
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/138856
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-138856
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Español
topic Astronomía
Galaxias
spellingShingle Astronomía
Galaxias
Navarro, J.
Mosconi, M.
García-Lambas, D.
Merging instability in groups of galaxies with dark matter
topic_facet Astronomía
Galaxias
description Several N-body experiments were performed in order to analyze the importance of smoothly distributed dark matter on the merging processes in groups of galaxies. We simulated groups of galaxies as self-gravitating systems of softened point masses with average intergalactic distance (Dₘ) ranging between 10 and 30 in units of the mean galactic half mass radius, and a cluster velocity dispersion to mean galactic internal velocity dispersion ratio (V_cl/σ_g) of about 2. A giant central galaxy ('cannibal') develops in less than a free fall time τ_ff when no background of dark matter is present. Only the galaxies which could acquire escape velocity, and thus leave the system, can avoid merging with the cannibal. This situation arises regardless of the initial dynamical conditions were imposed, which ranged from 'cold' models (all galaxies at rest) to equilibrium models (started with galaxies in virial equilibrium). We also tried initial conditions in which galaxies were moving in random directions with random velocity (rnd models) and found no difference in the time-scale of the process mentioned above. Thus groups of galaxies with no background cannot avoid merging into a single unit in a time-scale (∼ 1 τ_ff) much shorter than the expected life of such systems. The efficiency of the merging process is remarkably diminished when the effects of a massive background are included in the simulations. The more important the background in the dynamics of the system, the longer the system can stand without being cannibalized by a continuously growing galaxy, although keeping similar initial values for Dₘ and V_cl/σ_g. However when such a galaxy has 'eaten' about half of the mass in form of a galaxy, the process accelerates itself and the cannibal is rapidly formed. So, it must be concluded that such a dominant background is actually present if groups of galaxies are, as commonly assumed, older than five crossing times, because systems in which most of the mass is concentrated in galaxies appear to be largely unstable to merging.
format Articulo
Comunicacion
author Navarro, J.
Mosconi, M.
García-Lambas, D.
author_facet Navarro, J.
Mosconi, M.
García-Lambas, D.
author_sort Navarro, J.
title Merging instability in groups of galaxies with dark matter
title_short Merging instability in groups of galaxies with dark matter
title_full Merging instability in groups of galaxies with dark matter
title_fullStr Merging instability in groups of galaxies with dark matter
title_full_unstemmed Merging instability in groups of galaxies with dark matter
title_sort merging instability in groups of galaxies with dark matter
publishDate 1987
url http://sedici.unlp.edu.ar/handle/10915/138856
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AT mosconim merginginstabilityingroupsofgalaxieswithdarkmatter
AT garcialambasd merginginstabilityingroupsofgalaxieswithdarkmatter
bdutipo_str Repositorios
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