| Summary: | 碩士 === 國立臺灣師範大學 === 地球科學系 === 106 === Scaling relations of early-type galaxies (ETGs) connect galaxy properties. The ETG fundamental plane is one of the earliest examples that correlates effective radius Re with velocity dispersion σ. and surface brightness and is applied to estimate distance (Dressler 1987; Djorgovski and Davis 1987). Follow-up studies frequently utilize this scaling technique to find correlations among different properties of ETGs. In this study, based on the energy point of view, we construct our virial Fundamental Plane (vFP) with two variables of total mass density (ρ ~ M/V) and Virial Energy Density (VED ~ M2/ReV) to correlate properties of early-type galaxies, such as mass M, luminosity L, Re, σ and Age. Two sets of sample, core sample and extended sample, are included. The core sample includes 258 ETGs (z < 0.011), which are adopted from the ATLAS3D project (Cappellari et al. 2011, 2013b). The extended sample includes 3,128 ETGs (0.01< z < 0.1), which are selected from 14,034 galaxies (Nair and Abraham 2010), a subset of SDSS Data Release 4 (DR4).
The results show that the properties of ETGs can be well constrained by the ρ -VED vFP, which could construct surfaces of σRe, σRe/8, Vcirc, L, E/L and Age. The vFP can define the MDM –surface, which offers a good solution to estimate the DM masses within one Re of ETGs. Simultaneously, the obtained DM masses could transform the distribution of Mstar –surface and the Mtotal –surface from a random type to a flat type with small thicknesses. We also note that both the stellar mass and dark matter mass are significantly correlated with ETG ellipticity ε, if it is not ignored in the galaxy volume estimate. The connections are Mstar ~ Mtotal(1−ε)0.5 and MDM ~ Re Mtotal0.5 (1−ε)0.75. Our results also reveal that the more massive ETGs are, the lower their mass density, which means if an ETG grows via multiple -merging evolution and keeps the original masses of the mergers, its volume becomes larger than the sum of the individual volumes of the mergers. On the other hand, the mass-to-light ratio and the stellar-to-dynamical mass ratio also evolve during the lifetime of ETGs, as our obtained correlations suggest Mstar ⁄L ~ Age (1/0.93~0.96) and Mtotal ⁄L ~ Age (1/1.00~1.02).
Keywords: ETGs, fundamental plane (FP), vFP, VED, galaxy properties, property surface
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