Structural properties of disk galaxies. I. The intrinsic equatorial ellipticity of bulges

Méndez-Abreu, J.; Aguerri, J. A. L.; Corsini, E. M.; Simonneau, E.
Referencia bibliográfica

Astronomy and Astrophysics, Volume 478, Issue 2, February I 2008, pp.353-369

Fecha de publicación:
2
2008
Número de autores
4
Número de autores del IAC
1
Número de citas
150
Número de citas referidas
133
Descripción
Context: A variety of formation scenarios have been proposed to explain the diversity of properties observed in bulges. Studying their intrinsic shape can help to constrain the dominant mechanisms at the epochs of their assembly. Aims: 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 of the intrinsic equatorial ellipticity of bulges. Methods: We present a new fitting algorithm (GASP2D) to perform two-dimensional photometric decomposition of the 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 probability distribution function of the equatorial ellipticity of the bulges was derived from the distribution of the observed ellipticities of bulges and misalignments between bulges and disks. Results: 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 < B/A > = 0.85. Their probability distribution function is not significantly dependent on morphology, light concentration or luminosity. The possible presence of nuclear bars does not influence our results. Conclusions: The interplay between bulge and disk parameters favors scenarios in which bulges have assembled from mergers and/or have grown over long times through disk secular evolution. However, all these mechanisms have to be tested against the derived distribution of bulge intrinsic ellipticities. Table 3 is only available in electronic form at http://www.aanda.org
Proyectos relacionados
Imagen del Proyecto
Grupo de Estudios de Formación Estelar GEFE
El proyecto interno GEFE está enmarcado en el proyecto coordinado, ESTALLIDOS, financiado por el plan nacional desde el año 2001. El ultimo proyecto aprobado es ESTALLIDOS 6.0 (AYA2016- 79724-C4-2-P). En el proyecto GEFE trabajamos en base al caso científico del proyecto ESTALLIDOS 6.0. Los estallidos de formación estelar (Starbursts o SB) son
Casiana
Muñoz Tuñón
Abell 370 se encuentra a aproximadamente 4 mil millones de años luz de distancia en la constelación de Cetus, el monstruo marino
Evolución de Galaxias en Cúmulos
Las estructuras en el Universo, a todas las escalas de masa, se han formado de una forma jerárquica y principalmente producidas por fusiones de galaxias. Sin embargo, esta formación jerárquica de las galaxias está modulada por el entorno en el cual se crean y evolucionan. Mientras que las galaxias de campo presentan una evolución pasiva, los
Jairo
Méndez Abreu