Lee S. Kelvin, Simon P. Driver, Aaron S. G. Robotham, David T. Hill, Mehmet Alpaslan, Ivan K. Baldry, Steven P. Bamford, Joss Bland-Hawthorn, Sarah Brough, Alister W. Graham, Boris Häussler, Andrew M. Hopkins, Jochen Liske, Jon Loveday, Peder Norberg, Steven Phillipps, Cristina C. Popescu, Matthew Prescott, Edward N. Taylor, Richard J. Tuffs
We present single-S\'ersic two-dimensional model fits to 167,600 galaxies
modelled independently in the ugrizYJHK bandpasses using reprocessed Sloan
Digital Sky Survey Data Release Seven (SDSS DR7) and UKIRT Infrared Deep Sky
Survey Large Area Survey (UKIDSS-LAS) imaging data available from the GAMA
database. In order to facilitate this study we developed SIGMA, an R wrapper
around several contemporary astronomy software packages including Source
Extractor, PSF Extractor and GALFIT 3. SIGMA produces realistic 2D model fits
to galaxies, employing automatic adaptive background subtraction and empirical
PSF measurements on the fly for each galaxy in GAMA. Using these results, we
define a common coverage area across the three GAMA regions containing 138,269
galaxies. We provide S\'ersic magnitudes truncated at 10 re which show good
agreement with SDSS Petrosian and GAMA photometry for low S\'ersic index
systems (n < 4), and much improved photometry for high S\'ersic index systems
(n > 4), recovering as much as \Delta m = 0.5 magnitudes in the r band. We
employ a K band S\'ersic index/u - r colour relation to delineate the massive
(n > ~2) early-type galaxies (ETGs) from the late-type galaxies (LTGs). The
mean S\'ersic index of these ETGs shows a smooth variation with wavelength,
increasing by 30% from g through K. LTGs exhibit a more extreme change in
S\'ersic index, increasing by 52% across the same range. In addition, ETGs and
LTGs exhibit a 38% and 25% decrease respectively in half-light radius from g
through K. These trends are shown to arise due to the effects of dust
attenuation and stellar population/metallicity gradients within galaxy
populations.
View original:
http://arxiv.org/abs/1112.1956
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