摘要(英) |
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. |
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