IATE   20350
INSTITUTO DE ASTRONOMIA TEORICA Y EXPERIMENTAL
Unidad Ejecutora - UE
artículos
Título:
Environmental Influences on the Morphology & Dynamics of Group Size Haloes
Autor/es:
RAGONE-FIGUEROA C.; PLIONIS M.
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Editorial:
Blackwell Publishing Limited.
Referencias:
Lugar: Londres, Reino Unido; Año: 2007 vol. 377 p. 1785 - 1794
ISSN:
0035-8711
Resumen:
We use group-sized haloes, with masses in the range 1013 <
M < 2 × 1014h-1Msolar,
identified with a `friends of friends' (FOF) algorithm in a concordance
Λ cold dark matter (ΛCDM) GADGET2 (dark matter only)
simulation to investigate the dependence of halo properties on the
environment at z = 0. The study is carried out using samples of haloes
at different distances from their nearest massive cluster halo,
considered as such if its mass is larger than the upper limit of the
above halo mass range (i.e. M >= 2 ×
1014h-1Msolar). We find that the
fraction of haloes with substructure typically increases in high-density
regions. The halo mean axial ratio <c/a> also increases in
overdense regions, a fact which is true for the whole range of halo mass
studied. This can be explained as a reflection of an earlier halo
formation time in high-density regions, which gives haloes more time to
evolve and become more spherical. Moreover, this interpretation is
supported by the fact that, at a given halo-cluster distance, haloes
with substructure are more elongated than their equal mass counterparts
with no substructure, reflecting that the virialization (and thus
sphericalization) process is interrupted by merger events. The velocity
dispersion of low-mass haloes with strong substructure shows a
significant increase near massive clusters with respect to equal mass
haloes with low levels of substructure or with haloes found in
low-density environments. The alignment signal between the shape and the
velocity ellipsoid principal axes decreases going from lower to higher
density regions, while such an alignment is stronger for haloes without
substructure. We also find, in agreement with other studies, a tendency
of halo major axes to be aligned and of minor axes to lie roughly
perpendicular with the orientation of the filament within which the halo
is embedded, an effect which is stronger in the proximity of the massive
clusters.