Structural properties of discs and bulges of early-type galaxies

被引:40
作者
de Jong, RS
Simard, L
Davies, RL
Saglia, RP
Burstein, D
Colless, M
McMahan, R
Wegner, G
机构
[1] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[2] Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7, Canada
[3] Univ Oxford, Oxford OX1 3RH, England
[4] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[5] Arizona State Univ, Dept Phys & Astron, Tempe, AZ 85287 USA
[6] Anglo Australian Observ, Epping, NSW 1710, Australia
[7] Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA
[8] Dartmouth Coll, Dept Phys & Astron, Wilder Lab, Hanover, NH 03755 USA
关键词
galaxies : elliptical and lenticular; cD; galaxies : fundamental parameters; galaxies : statistics; galaxies : structure;
D O I
10.1111/j.1365-2966.2004.08394.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have used the EFAR sample of galaxies to investigate the light distributions of early-type galaxies. We decompose the two-dimensional 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 if we assume that all galaxies can have a spheroidal and a disc component, then the brightest, bulge-dominated elliptical galaxies have a fairly broad distribution in the Sersic profile shape parameter n(B), with a median of approximately 3.7 and with sigma similar to 0.9. Other galaxies have smaller n(B) values. This means that spheroids are in general less concentrated than the de Vaucouleurs R-1/4-law profile, which has n(B) = 4. While the result of our light decomposition is robust, we cannot prove without kinematic information that these components are spheroids and discs, in the usual sense of pressure- and rotation-supported stellar systems. However, we show that the distribution of disc inclination angles is consistent with a random orientation if we take our selection effects into account. 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 the luminosity dimension and a lognormal 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, but extending to brighter magnitudes; at fainter luminosities the scale size distribution of elliptical galaxies peaks at distinctly smaller sizes than the size distribution of spiral galaxies; and (5) bulge components of early-type galaxies are typically a factor of 1.5-2.5 smaller than the discs of spiral galaxies with a slight luminosity dependence, while disc components of early-type galaxies are typically twice as large as the discs of spiral galaxies at all luminosities.
引用
收藏
页码:1155 / 1170
页数:16
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