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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
GEMS: Galaxy fitting catalogs and testing parametric galaxy fitting codes: GALFIT and GIM2D
Astrophysical Journal, Supplement Series, Volume 172, No. 2, Year 2007
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Description
In the context of measuring the structures of intermediate-redshift galaxies with HSTACS surveys, we tune, test, and compare two widely used fitting codes (GALFIT and GIM2D) for fitting single-component Sérsic models to both simulated and real galaxy data. Our study focuses on the GEMS survey with the sensitivity of typical HST survey data, and we include our final catalog of fit results for all 41,495 objects detected in GEMS. Using simulations, we find that fitting accuracy depends sensitively on galaxy profile shape. Exponential disks are well fit and have small measurement errors, whereas fits to de Vaucouleurs profiles show larger uncertainties owing to the large amount of light at large radii. Both codes provide reliable fits with little systematic error for galaxies with effective surface brightnesses brighter than that of the sky; the formal uncertainties returned by these codes significantly underestimate the true uncertainties (as estimated using the simulations). We find that GIM2D suffers significant systematic errors for spheroids with close companions owing to the difficulty of effectively masking out neighboring galaxy light; there appears to be no work-around to this important systematic in GIM2D's current implementation. While this crowding error affects only a small fraction of galaxies in GEMS, it must be accounted for in the analysis of deeper cosmological images or of more crowded fields with GIM2D, In contrast, GALFIT results are robust to the presence of neighbors because it can simultaneously fit the profiles of multiple companions as well as the galaxy of interest. We find GALFIT's robustness to nearby companions and factor of ≳20 faster runtime speed are important advantages over GIM2D for analyzing large HSTACS data sets. © 2007. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Häussler, Boris
Germany, Heidelberg
Max Planck Institute for Astronomy
McIntosh, Daniel H.
United States, Amherst
University of Massachusetts Amherst
Bell, Eric F.
Germany, Heidelberg
Max Planck Institute for Astronomy
Rix, Hans Walter R.
Germany, Heidelberg
Max Planck Institute for Astronomy
Caldwell, John A.R.
United States, Austin
University of Texas System
Heymans, Catherine E.
Canada, Vancouver
The University of British Columbia
Jahnke, Knud
Germany, Heidelberg
Max Planck Institute for Astronomy
Jogee, Shardha
United States, Austin
The University of Texas at Austin
Koposov, Sergey E.
Germany, Heidelberg
Max Planck Institute for Astronomy
Meisenheimer, Klauss
Germany, Heidelberg
Max Planck Institute for Astronomy
Sánchez, Sebastián F.
Spain, Almeria
Centro Astronómico Hispano-alemán
Somerville, Rachel S.
Germany, Heidelberg
Max Planck Institute for Astronomy
Wisotzki, Lutz
Germany, Potsdam
Universität Potsdam
Statistics
Citations: 227
Authors: 13
Affiliations: 10
Identifiers
Doi:
10.1086/518836
ISSN:
00670049
Study Design
Cross Sectional Study
Study Approach
Quantitative