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Article overview
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Scaling Relations and the Fundamental Line of the Local Group Dwarf Galaxies | | Joanna Woo
; Stephane Courteau
; Avishai Dekel
; | | Date: |
9 Jul 2008 | | Abstract: | We study the scaling relations between global properties of dwarf galaxies in
the Local Group. In addition to quantifying the correlations between pairs of
variables, we explore the "shape" of the distribution of galaxies in log
parameter space using standardised Principal Component Analysis (PCA), the
analysis is performed first in the 3-D structural parameter space of stellar
mass M*, internal velocity V and characteristic radius R* (or surface
brightness mu*). It is then extended to a 4-D space that includes a
stellar-population parameter such as metallicity Z or star formation rate SFR.
We find that the Local-Group dwarfs basically define a one-parameter
"Fundamental Line" (FL), primarily driven by stellar mass, M*. A more detailed
inspection reveals differences between the star-formation properties of dwarf
irregulars (dI’s) and dwarf ellipticals (dE’s), beyond the tendency of the
latter to be more massive. In particular, the metallicities of dI’s are
typically lower by a factor of 3 at a given M* and they grow faster with
increasing M*, showing a tighter FL in the 4-D space for the dE’s. The
structural scaling relations of dI’s resemble those of the more massive
spirals, but the dI’s have lower star formation rates for a given M* which also
grow faster with increasing M*. On the other hand, the FL of the dE’s departs
from the fundamental plane of bigger ellipticals. While the one-parameter
nature of the FL and the associated slopes of the scaling relations are
consistent with the general predictions of supernova feedback (Dekel & Woo
2003), the differences between the FL’s of the dE’s and the dI’s remain a
challenge and should serve as a guide for the secondary physical processes
responsible for these two types. | | Source: | arXiv, 0807.1331 | | Services: | Forum | Review | PDF | Favorites | |
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