2012/11/30 by Alan Meert, A. Meert, Vinu Vikram +1 · 74 citations
Physics and Astronomy · #Approx #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Effective radius #Exponential function #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Magnitude (astronomy) #Physics #RADIUS #Sigma #Sky #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stt822
published in Monthly Notices of the Royal Astronomical Society 433(2), 1344-1361 (Oxford University Press) · 19 pages, 17 figures, Version accepted to MNRAS
openalex publication_date 2013/06/04 · arxiv created 2013/06/06 · arxiv updated 2013/06/10 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the results of fitting simulations of an unbiased sample of Sloan Digital Sky Survey (SDSS) galaxies utilizing the fitting routine galfit and analysis pipeline pymorph. These simulations are used to test the two-dimensional decompositions of SDSS galaxies. The simulations show that single Sérsic models of SDSS data are recovered with σmag ≈ 0.025 mag and σradius ≈ 5 per cent. The global values (half-light radius and magnitude) are equally well constrained when a two-component model is used. Sub-components of two-component models present more scatter. SDSS resolution is the primary source of error in the recovery of models. We use a simple statistical correction of the biases in fitted parameters, providing an example using the Sérsic index. Fitting a two-component Sérsic + Exponential model to a single Sérsic galaxy results in a noisier, but unbiased, recovery of the input parameters (σtotalmag ≈ 0.075 mag and σradius ≈ 10 per cent); fitting a single Sérsic profile to a two-component system results in biases of total magnitude and half-light radius of ≈ 0.05-0.10 mag and 5–10 per cent in radius. Using an F-test to select the best-fitting model from among the single- and two-component models is sufficient to remove this bias. We recommend fitting a two-component model to all galaxies when attempting to measure global parameters such as total magnitude and half-light radius.