Dissipationless collapse and the formation of elliptical galaxies

A brief review of previous work and the present situation in the problem of formation of elliptical galaxies via dissipation-less collapse are presented, as well as the results of a new set of numerical experiments. It is shown that collapses started from cold initial conditions are different from w...

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Autor principal: Aguilar, L. A.
Formato: Articulo Comunicacion
Lenguaje:Español
Publicado: 1987
Materias:
Astronomía
Galaxias
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/138379
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-138379
record_format dspace
spelling I19-R120-10915-1383792024-09-09T18:28:38Z http://sedici.unlp.edu.ar/handle/10915/138379 Dissipationless collapse and the formation of elliptical galaxies Aguilar, L. A. 1987 2022-06-27T13:32:31Z es Astronomía Galaxias A brief review of previous work and the present situation in the problem of formation of elliptical galaxies via dissipation-less collapse are presented, as well as the results of a new set of numerical experiments. It is shown that collapses started from cold initial conditions are different from warmer collapses, due to the presence of a dynamical instability associated with radial orbits. This instability leads to triaxial final configurations, regardless of the initial amount of random kinetic energy, rotational kinetic energy, or shape of the initial conditions, as long as 2T/W ≲ 0.1, where T is the total (rotational plus thermal) kinetic energy and W is the potential energy of the initial conditions. Warmer initial conditions preserve their initial shape, or become oblate if initially rotating. Cold initial conditions produce equilibrium system with realistic density profiles, an opposed to collapses from warmer conditions that result in core-halo profiles, unlike the observed surface brightness profiles of elliptical galaxies. Although the same cold collapses that result in triaxial shapes produce realistic density profiles, it is shown that these two effects are not directly connected: cold collapses simulated with an N-body code that enforces spherical symmetry result in realistic density profiles too. Asociación Argentina de Astronomía Articulo Comunicacion http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) application/pdf
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
Aguilar, L. A.
Dissipationless collapse and the formation of elliptical galaxies
topic_facet Astronomía
Galaxias
description A brief review of previous work and the present situation in the problem of formation of elliptical galaxies via dissipation-less collapse are presented, as well as the results of a new set of numerical experiments. It is shown that collapses started from cold initial conditions are different from warmer collapses, due to the presence of a dynamical instability associated with radial orbits. This instability leads to triaxial final configurations, regardless of the initial amount of random kinetic energy, rotational kinetic energy, or shape of the initial conditions, as long as 2T/W ≲ 0.1, where T is the total (rotational plus thermal) kinetic energy and W is the potential energy of the initial conditions. Warmer initial conditions preserve their initial shape, or become oblate if initially rotating. Cold initial conditions produce equilibrium system with realistic density profiles, an opposed to collapses from warmer conditions that result in core-halo profiles, unlike the observed surface brightness profiles of elliptical galaxies. Although the same cold collapses that result in triaxial shapes produce realistic density profiles, it is shown that these two effects are not directly connected: cold collapses simulated with an N-body code that enforces spherical symmetry result in realistic density profiles too.
format Articulo
Comunicacion
author Aguilar, L. A.
author_facet Aguilar, L. A.
author_sort Aguilar, L. A.
title Dissipationless collapse and the formation of elliptical galaxies
title_short Dissipationless collapse and the formation of elliptical galaxies
title_full Dissipationless collapse and the formation of elliptical galaxies
title_fullStr Dissipationless collapse and the formation of elliptical galaxies
title_full_unstemmed Dissipationless collapse and the formation of elliptical galaxies
title_sort dissipationless collapse and the formation of elliptical galaxies
publishDate 1987
url http://sedici.unlp.edu.ar/handle/10915/138379
work_keys_str_mv AT aguilarla dissipationlesscollapseandtheformationofellipticalgalaxies
_version_ 1809774293151645696

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