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Environmental Effects on the physical properties of galaxies: Clues to the formation of S0 galaxies
Acceso Abierto
Clusters of galaxies
In this thesis, we have investigated the origin of S0 galaxies and the density morphology relation (DMR Dressler 1980b). The DMR states that elliptical and S0 galaxies inhabit regions of high galaxy density, such as clusters of galaxies. Many scenarios try to explain this relation, and range from environmental effects to clusters' intrinsic properties. Among the identified environmental effects are tidal effects, galaxy harassment, ram pressure, starvation, galaxy encounters, or thermal evaporation. To address this problem, we have analyzed the structure of galaxies of low-redshift (z) X-ray selected Abell Clusters, using R-band wide field CCD images obtained with the Kitt Peak National Observatory (KPNO) 0:9 m telescope. We have developed the Driver for GALFIT on Cluster Galaxies (DGCG), a script program in Perl to drive GALFIT code (Peng et al. 2002) almost automatically on crowded fields. DGCG has build-in routines to select objects, and depending on their proximity it can either mask or model neighboring objects. We have tested DGCG with synthetic models of galaxies, and have shown that the simultaneous fitting approach is better than the masking method for galaxies that are close together in the line of sight. The final sample contains 1453 galaxies out of 2419 from 21 galaxy clusters from the Low-Redshift Optical Cluster Survey (LOCOS López-Cruz et al. 2004). DGCG fitted 2419 galaxies using two approaches: a single Sérsic model and two-component model (Sérsic + Exponential). As a result, 2227 (92%) galaxies have reached suitable models. As an important part of this thesis, we have proposed a new classification scheme by combining bulge to total luminosity ratio, axis ratio, bumpiness and Sérsic index, which has allowed us to segregate three classes: spiral, S0 and elliptical (S-S0-E) galaxies. We used Dressler (1980a) classifications to calibrate this proposed classification method. We have recovered the DMR, the Kormendy relation (KR), the luminosity-size relation (LSR), the Faber-Jackson relation (FJR), and the fundamental plane (FP). We have identified bulges and pseudobulges using the KR; this has allowed us to discover that the FJR can also be used to segregate pseudobulges from bulges. The FP for bulges and pseudobulges have different slopes. Using the distribution of the Sérsic index and the surface brightness profiles by morphological type, we have provided evidence that gravitational dynamical processes formed S0 galaxies.
Instituto Nacional de Astrofísica, Óptica y Electrónica
Tesis de doctorado
Público en general
Añorve-Solano C.
Versión aceptada
acceptedVersion - Versión aceptada
Appears in Collections:Doctorado en Astrofísica

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