Bulges and Disks in the Nearby Universe: Applications to Evolution and Formation of Galaxies

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Doctor of Philosophy (PhD)
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Physics & Astronomy
Fundamental Parameters
Astrophysics and Astronomy
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We present a catalog of 2D, PSF-corrected de Vacouleurs, Sersic, de Vacouleurs + Exponential, and Sersic + Exponential fits of ~7 x 10^5 spectroscopically selected galaxies drawn from the Sloan Digital Sky Survey (SDSS) Data Release 7. Fits are performed for the SDSS r-band utilizing the fitting routine Galfit and analysis pipeline PyMorph. Simulations are used to test the two-dimensional decompositions of SDSS galaxies. We compare these fits to prior catalogs and present a physically motivated flagging system which suggests that more than 90 per cent of two-component fits can be used for analysis. The catalogs provide a robust set of structural and photometric parameters for future galaxy studies. The catalog is then extended into the g-band and i-band. The data and fitted images are available online at http://shalaowai.physics.upenn.edu/~ameert/fit_catalog/. Two applications of the catalog are presented. The sensitivity to the choice of light profile and its affect on the massive end of the stellar mass function is quantified. The total stellar mass density at z ~ 0.1 is about 1.2 times larger than in previous analysis of the SDSS using the new catalog. The differences are most pronounced at the massive end, where the measured number density of objects having M_star greater than or equal to 6 x 10^11 M_sun is approximately five times larger. The systematics of fitting different model profiles on the size-luminosity relation of galaxies in the SDSS (i.e. at z ~ 0.1) are also quantified in the r-band. The net effect on the R-L relation is small, except for the most luminous tail. Neither the early- nor the late-type relations are pure power laws: both show significant curvature, which we quantify. This curvature confirms that two mass scales are special for both early- and late-type galaxies: M_star ~ 3 x 10^10 and 2 x 10^11 M_sun. The intrinsic scatter in the R-L relation is shown to decrease at large L and/or M_star and should provide additional constraints on models of how the most massive galaxies formed. Future work applying the analysis to DES and LSST galaxies at higher redshifts is suggested to further constrain models of galaxy formation and evolution at higher redshifts.

Mariangela Bernardi
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