Bibcode
Méndez-Abreu, J.; Aguerri, J. A. L.; Corsini, E. M.; Simonneau, E.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 487, Issue 2, 2008, pp.555-556
Advertised on:
8
2008
Revista
Número de citas
13
Número de citas referidas
12
Descripción
(Abridged) A variety of formation scenarios was proposed to explain the
diversity of properties observed in bulges. Studying their intrinsic
shape can help in constraining the dominant mechanism at the epochs of
their assembly. The structural parameters of a magnitude-limited sample
of 148 unbarred S0--Sb galaxies were derived in order to study the
correlations between bulges and disks as well as the probability
distribution function (PDF) of the intrinsic equatorial ellipticity of
bulges. It is presented a new fitting algorithm (GASP2D) to perform the
two-dimensional photometric decomposition of galaxy surface-brightness
distribution. This was assumed to be the sum of the contribution of a
bulge and disk component characterized by elliptical and concentric
isophotes with constant (but possibly different) ellipticity and
position angles. Bulge and disk parameters of the sample galaxies were
derived from the J-band images which were available in the Two Micron
All Sky Survey. The PDF of the equatorial ellipticity of the bulges was
derived from the distribution of the observed ellipticities of bulges
and misalignments between bulges and disks. Strong correlations between
the bulge and disk parameters were found. About 80% of bulges in
unbarred lenticular and early-to-intermediate spiral galaxies are not
oblate but triaxial ellipsoids. Their mean axial ratio in the equatorial
plane is = 0.85. There is not significant dependence of
their PDF on morphology, light concentration, and luminosity. The
interplay between bulge and disk parameters favors scenarios in which
bulges assembled from mergers and/or grew over long times through disk
secular evolution. But all these mechanisms have to be tested against
the derived distribution of bulge intrinsic ellipticities.