TY - JOUR
T1 - GEMS
T2 - Galaxy fitting catalogs and testing parametric galaxy fitting codes: GALFIT and GIM2D
AU - Häussler, Boris
AU - McIntosh, Daniel H.
AU - Barden, Marco
AU - Bell, Eric F.
AU - Rix, Hans Walter
AU - Borch, Andrea
AU - Beckwith, Steven V.W.
AU - Caldwell, John A.R.
AU - Heymans, Catherine
AU - Jahnke, Knud
AU - Jogee, Shardha
AU - Koposov, Sergey E.
AU - Meisenheimer, Klaus
AU - Sánchez, Sebastian F.
AU - Somerville, Rachel S.
AU - Wisotzki, Lutz
AU - Wolf, Christian
PY - 2007
Y1 - 2007
N2 - 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.
AB - 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.
KW - Catalogs
KW - Galaxies: general
KW - Galaxies: photometry
KW - Galaxies: statistics
KW - Methods: data analysis
KW - Surveys
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U2 - 10.1086/518836
DO - 10.1086/518836
M3 - Article
AN - SCOPUS:35348848331
SN - 0067-0049
VL - 172
SP - 615
EP - 633
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
IS - 2
ER -