IATE   20350
INSTITUTO DE ASTRONOMIA TEORICA Y EXPERIMENTAL
Unidad Ejecutora - UE
artículos
Título:
Galaxy-induced transformation of dark matter haloes
Autor/es:
ABADI, MARIO G.; NAVARRO, JULIO F.; FARDAL, MARK; BABUL, ARIF; STEINMETZ, MATTHIAS
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2010 vol. 407 p. 435 - 446
ISSN:
0035-8711
Resumen:
We use N-body/gasdynamical cosmological simulations to examine
the effect of the assembly of a central galaxy on the shape and mass
profile of its surrounding dark matter halo. Two series of simulations
are compared; one that follows only the evolution of the dark matter
component of individual haloes in the proper Λcold dark matter (ΛCDM)
cosmological context, and a second series where a baryonic component is
added and followed hydrodynamically. The simulations with baryons
include radiative cooling but neglect the formation of stars and their
feedback. The efficient, unimpeded cooling that results leads most
baryons to collect at the halo centre in a centrifugally supported disc
which, due to angular momentum losses, is too small and too massive when
compared with typical spiral galaxies. This admittedly unrealistic
model allows us, nevertheless, to gauge the maximum effect that galaxies
may have in transforming their surrounding dark haloes. We find, in
agreement with earlier work, that the shape of the halo becomes more
axisymmetric: post galaxy assembly, haloes are transformed from triaxial
into essentially oblate systems, with well-aligned isopotential
contours of roughly constant flattening (〈c/a〉∼ 0.85).
Haloes always contract as a result of galaxy assembly, but the effect
is substantially less pronounced than predicted by the traditional
adiabatic-contraction hypothesis. The reduced contraction helps to
reconcile ΛCDM haloes with constraints on the dark matter content inside
the solar circle and should alleviate the longstanding difficulty of
matching simultaneously the scaling properties of galaxy discs and the
galaxy luminosity function. The halo contraction we report is also less
pronounced than found in earlier simulations, a disagreement which
suggests that halo contraction is not solely a function of the initial
and final distribution of baryons. Not only how much baryonic mass has
been deposited at the centre of a halo matters, but also the mode of its
deposition. Although simple formulae might work in particular cases
where galaxies form nearly adiabatically, in general it might prove
impossible to predict the halo response to galaxy formation without a
detailed understanding of a galaxy's detailed assembly history.