Surface Photometry and Radial Color Gradients of Nearby Luminous Early-type Galaxies in SDSS Stripe 82 - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: We make use of the images from the Sloan Digital Sky Survey Stripe 82 topresent an analysis of r band surface brightness profiles and radial colorgradients g - r, u - r in 111 nearby early-type galaxies ETGs. With Stripe82 images, we are able to pay special attentions to the low-surface-brightnessareas LSB areas of the galaxies. The LSB areas make a difference to theSersic fittings and concentration indices, making both the indices less thanthe typical values for ETGs. There are about 60% negative color gradientsred-core within 1.5Re , much more than the approximately 10% positive onesblue-core within the same radius. However, taking into account of the LSBareas, we find that the color gradients are not necessarily monotonic: aboutone third of the red-core or blue-core galaxies have positive or negativecolor gradients in the outer areas. So LSB areas not only make ETGs- Sersicprofiles deviate from de Vaucouleur ones and shift to the disk end, but alsoreveal that quite a number of ETGs have opposite color gradients in inner andouter areas. These outcomes remind us the necessity of double-Sersic fitting.These LSB phenomena may be interpreted by mergers and thus differentmetallicity in the outer areas. Isophotal parameters are also discussed brieflyin this paper: more disky nearby ETGs are spotted than boxy ones.



Autor: Fangzhou Jiang, Song Huang, Qiusheng Gu

Fuente: https://arxiv.org/







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