Abstract Details
| Name: Laxmikant Chaware Affiliation: Pt. Ravishankar Shukla University, Raipur Conference ID: ASI2015_561 Title : Multiwavelength Study of Galaxies Using Deep Survey Fields Authors and Co-Authors : Laxmikant Chaware Pt. Ravishankar Shukla University, Raipur Abstract Type : Oral Abstract Category : Thesis Abstract : The deep images of six LFC fields at our disposal with excellent SNR and availability of complementary data for the fields in the public domain from the other surveys motivated us to (i) study the properties of the isophotal shapes of early-type galaxies (E/SO) to very faint outer regions, well beyond the levels reached by previous studies of this type. And, (ii) to explore Low Surface Brightness (LSB) galaxies which emit much less light per unit area than normal high surface brightness galaxies do and remain undetected in most of the observations because of the difficulty in detecting them against the night sky brightness. These exploit the fact that the data has been obtained through very long exposures with a 5m telescope, and therefore provides an opportunity to study low surface brightness regions of a large sample of galaxies. In this thesis work we generated photometric catalogs for all the objects that were detected in the images of six LFC fields. We performed surface photometry and bulge-disk decomposition for a large sample of galaxies chosen from each field. We carried out a redshift survey to derive absolute magnitudes and physical sizes of the galaxies using the 2dF/AAOmega multi-fiber system on the 4m Anglo Australian Telescope (AAT). We observed 673 galaxies with AAOmega and determined redshifts for 398 galaxies. We chose a well defined sample of 132 early-type galaxies from one of the LFC field SDSS 1208+0010 in which we have redshift information for maximum number of galaxies. We derive a range of isophotal shape parameters for sample galaxies that measure their ellipticity and orientation, and also higher order departures from a purely elliptical shape. We then derive mean values for these parameters in four radial bins along the semi major axis of each galaxy. We find empirical fitting formulae for the probability distribution of the different isophotal parameters in each bin, which will be useful for comparison with theoretical studies, e.g. from N-body simulations. We have investigated possible correlations of isophotal shape parameters with other global properties of the galaxies, and inspected whether the correlations change along the radius. Our main finding of the investigation is that the isophotal shapes of the inner regions of our sample of galaxies are statistically different from the isophotal shapes observed in the outer regions. In the central regions we see patterns similar to those seen in previous studies of nearby galaxies, with some galaxies showing 'boxy' isophotes while others appear 'disky'. However, the pattern seen in the inner region of each galaxy tends to change as the radius increases, suggesting that while the inner parts of the galaxies are coherent and presumably the result of specific dynamical processes, at larger radii the shapes and orientations of the isophotes change. This may indicate effects from the formation and evolution of each galaxy which are not yet fully relaxed. We performed a search for LSB galaxies in one of the LFC field m0836 and found 27 LSB galaxy candidates. |