copyright@sdss
Schematic diagram showing key sciences for unerstanding the structure formation and the background universes.
Automated Galaxy Morphology Classifier
Dr. Yun-Young Choi and Prof. Park have found found the u-r color versus g-i color gradient space can be used for highly successful morphology classication of galaxies in the Sloan Digital Sky Survey.
Park, Changbom, and Choi, Yun-Young, 2005, Astrophysical J., 635, L29-L32 [pdf]
In this space galaxies form early and late type branches well-separated from each other. The location of galaxies along the branches are the degree and locality of star formation activity, and monotonically corresponds to the sequence of morphological subclasses. When the concentration index is used together, the completeness and reliability of classication reaches about 91% for a training set of SDSS galaxies brighter than r_pet ~15.9.
Dr. Yun-Young Choi and Prof. Park have studied the relations among various physical properties of the SDSS galaxies and explored the relation between the environment and galaxy properties.
Park, Changbom, Choi, Y.-Y., Vogeley, M. S., Blanton, M. R., & Gott, J. R. 2007, ApJ, 658, in press [pdf]
Choi, Y.-Y., Park, Changbom, Vogeley, M. S., & Gott, J. R. 2007, ApJ, 658, in press [pdf]
It was found that, at fixed morphology and luminosity, early types show very small dispersions in color, color gradient, concentration, size, and velocity dispersion. Many parameters manifest different behaviors across the absolute
magnitude of about M*. They have also used a new local density estimator to explore the relation between the environment and galaxy properties. It was found that variations of galaxy properties with environment were almost entirely due to the dependence of morphology and luminosity on environment. When morphology and luminosity are fixed, other physical properties are nearly independent of local density without any break or feature. Weak residual dependences on environment include that of the color of late-types and of the luminosity-velocity dispersion relation of early types. Motivated by the study of effects of local density and the nearest companion on galaxy morphology, they have proposed a mechanism that the morphology of galaxies in galaxy systems is transformed by the tidal force.
Ongoing related-subtopics
Dr. Yun-Young Choi and Prof. Park have found found the u-r color versus g-i color gradient space can be used for highly successful morphology classication of galaxies in the Sloan Digital Sky Survey.
Park, Changbom, and Choi, Yun-Young, 2005, Astrophysical J., 635, L29-L32 [pdf]
In this space galaxies form early and late type branches well-separated from each other. The location of galaxies along the branches are the degree and locality of star formation activity, and monotonically corresponds to the sequence of morphological subclasses. When the concentration index is used together, the completeness and reliability of classication reaches about 91% for a training set of SDSS galaxies brighter than r_pet ~15.9.
Galaxy Formation
Dr. Yun-Young Choi and Prof. Park have studied the relations among various physical properties of the SDSS galaxies and explored the relation between the environment and galaxy properties.
Park, Changbom, Choi, Y.-Y., Vogeley, M. S., Blanton, M. R., & Gott, J. R. 2007, ApJ, 658, in press [pdf]
Choi, Y.-Y., Park, Changbom, Vogeley, M. S., & Gott, J. R. 2007, ApJ, 658, in press [pdf]
It was found that, at fixed morphology and luminosity, early types show very small dispersions in color, color gradient, concentration, size, and velocity dispersion. Many parameters manifest different behaviors across the absolute
magnitude of about M*. They have also used a new local density estimator to explore the relation between the environment and galaxy properties. It was found that variations of galaxy properties with environment were almost entirely due to the dependence of morphology and luminosity on environment. When morphology and luminosity are fixed, other physical properties are nearly independent of local density without any break or feature. Weak residual dependences on environment include that of the color of late-types and of the luminosity-velocity dispersion relation of early types. Motivated by the study of effects of local density and the nearest companion on galaxy morphology, they have proposed a mechanism that the morphology of galaxies in galaxy systems is transformed by the tidal force.
Ongoing related-subtopics
Effects
of Interactions on Galaxy Properties
Merging Galaxies
Satellite Galaxies
Merging Galaxies
Satellite Galaxies
Large-Scale Structure
Topology
of Main & Luminous Red Galaxies
We found clear evidence of luminosity and
Park, Changbom, Choi, Yun-Young, Vogeley, Michael, S., Gott, J. Richard, III, Kim, Juhan, Hikage, Chiaki, Matsubara, Takahiro, Park, Myeong-Gu, Suto, Yashushi, Weinberg, David, H. 2005, Astrophysical J., 633, 11-22 [pdf]
We found clear evidence of luminosity and
Park, Changbom, Choi, Yun-Young, Vogeley, Michael, S., Gott, J. Richard, III, Kim, Juhan, Hikage, Chiaki, Matsubara, Takahiro, Park, Myeong-Gu, Suto, Yashushi, Weinberg, David, H. 2005, Astrophysical J., 633, 11-22 [pdf]