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29 April 2024 |
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Article overview
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Structural properties of discs and bulges of early-type galaxies | Roelof S. de Jong
; Luc Simard
; Roger L. Davies
; R.P. Saglia
; David Burstein
; Matthew Colless
; Robert McMahan
; Gary Wegner
; | Date: |
5 Oct 2004 | Subject: | astro-ph | Abstract: | We have used the EFAR sample of galaxies to study the light distributions of early-type galaxies. We decompose the 2D light distribution of the galaxies in a flattened spheroidal component with a Sersic radial light profile and an inclined disc component with an exponential light profile. We show that the brightest, bulge dominated elliptical galaxies have a fairly broad distribution in the Sersic profile shape parameter n_B, with a median of about 3.7 and a sigma of ~0.9. Other galaxies have smaller n_B values, meaning that spheroids are in general less concentrated than the n_B=4 de Vaucouleurs-law profile. The results of our light decompositions are robust, even though without kinematic information we cannot prove that the spheroids and discs are really pressure- and rotation-supported stellar systems. If we assume that the detected spheroids and discs are indeed separate components, we can draw the following conclusions: 1) the spheroid and disc scale sizes are correlated; 2) bulge-to-total luminosity ratios, bulge effective radii, and bulge n_B values are all positively correlated; 3) the bivariate space density distribution of elliptical galaxies in the (luminosity, scale size)-plane is well described by a Schechter luminosity function in and a log-normal scale-size distribution at a given luminosity; 4) at the brightest luminosities, the scale size distribution of elliptical galaxies is similar to those of bright spiral galaxies; at fainter luminosities the elliptical scale size distribution peaks at distinctly smaller sizes than the spiral galaxy distribution; and 5) bulge components of early-type galaxies are typically a factor 1.5 to 2.5 smaller than the disks of spiral galaxies, while disc components of early-type galaxies are typically twice as large as the discs of spiral galaxies. [abridged] | Source: | arXiv, astro-ph/0410121 | Services: | Forum | Review | PDF | Favorites |
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