A Multi-Wavelength Study of Fundamental plane and Effective Radius in Elliptical Galaxies

• Main Authors: ShengFeng Yen, 顏聖峰
• Other Authors: Chung-Ming Ko
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/d29y2z

碩士 === 國立中央大學 === 天文研究所 === 97 === In this thesis, we collect a catalog of 5707 galaxies from SDSS(g’,r’,i’,z’) which have counterpart in 2MASS(J,H,Ks). A subsample of 716 galaxies is selected for their larger effective angular size (effective radius larger than 3 aresec in all 7 bands). Both samples fit a fundamental plane (FP) as expected. We examine the FP for 7 bands including g’,r’,i’,z’,J,H,Ks. We work out the mass of each galaxy by two mass models (one is King’s model in Newtonian dynamics, one is polytropic model in MONDian dynamics). The Newtonian mass is always larger than MONDian mass. We note that the mass-to-light ratio depends on mass weakly. Assuming M/L ∝ M , we find that is different in different dynamics, in different band. The size of each galaxy depends on observing wavelength. We study the size-wavelength relation. We can classify the galaxies into four groups. (1) single power law from optical to infrared, (2) a break in effective radius between optical and infrared, (3) a minimum around the transition between optical and infrared, (4) cannot be classified into the previous 3 classes. We expect that the size is more reliable in the larger galaxies samples, and find that in this sample, 62.3% are class-1, 21.2% are class-2, 10.5% are class-3, and 6.0% are class-4. In other world, there are more than 80 % ellipticals have more concentrated older star population than younger one.