VizieR Online Data Catalog: GAMA. MegaMorp/GalfitM profile fits (Haeussler+, 2022)

This catalogue provides the results of fitting both a single Sersic component model as well as a two-component bulge-disk model to the 2D surface brightness distributions of galaxies in the GAMA II G09/G12/G15 survey (Driver et al., 2011MNRAS.413..971D, J/MNRAS/413/971) regions using the http://www.nottingham.ac.uk/astronomy/megamorph MegaMorph multi-band fitting method, Galapagos-2 (Haeussler et al., 2013MNRAS.430..330H, Barden et al., 2012MNRAS.422..449B) and GalfitM (Haeussler et al., 2013MNRAS.430..330H). In this method the ugri (from KiDS, de Jong et al., 2013ExA....35...25D) and zYJHK (from VIKING, Edge et al., 2013Msngr.154...32E, Cat. II/329) surface brightness distributions of a galaxy are fit simultaneously while imposing some constraints on how some of the model parameters are allowed to vary with wavelength.

Summary of fitting procedure are given in Haeussler et al., 2013MNRAS.430..330H, https://ui.adsabs.harvard.edu/abs/2013MNRAS.430..330H, and Haeussler et al. (2022A&A...664A..92H, this paper).

Some important information in order to use the catalogue are summarized here:

- PSFs have been created using PSFEx (astromatic, Bertin, 2011, ASP Conf. Ser., 442) using a dense grid. The closest PSF to an object has been chosen for the fit

- Source detection has been carried out using SExtractor (Bertin & Arnouts, 1996A&AS..117..393B), on the r-band image. SOurce identification has been carried out via a unique/best identification within 2 arcseconds.

- Component centres, axial ratios and position angles are constrained to be the same at all wavelengths

- We provide both a single Sersic model and two 2-component (Sersic + exponential (GA_{MMBD1) and deVauc + exponential (GA}MMBD4)) models to our sample. Sersic index and effective radius for the single Sersic fit are allowed to vary (up to) as a quadratic function of wavelength, whilst Sersic index and effective radius for each component of the 2-component fit are constant with wavelength (==4 in case of de Vaucouleurs profiles f the bulges).

- In all cases an 8th-order polynomial is used for magnitude, which is therefore effectively free to vary between bands. The MAG*CHEB values are hence to be used with a big grain of salt to interpolate values.

- Effective filter wavelengths are used as follows for the polynomial fits u-band: 3543Å g-band: 4770Å r-band: 6231Å i-band: 7625Å z-band: 9134Å Y-band: 10305Å J-band: 12483Å H-band: 16313Å K/Ks-band: 22010Å

Chebyshev values for magnitudes (warning!) Chebyshev values for magnitudes in all fits apply full freedom, (e.g. polynomial of 8th order for 9 bands). As such, the polynomial between the mentioned wavelengths are unconstrained and not ideal for interpolating magnitudes. In practice, they are often smooth, but care should be taken when trying to interpolate the wavelengths to, e.g., restframe wavelengths. Chebyshev polynomials for halflight radius and sersic index are of lower value and can be interpreted without issue

We advice users to carefully select their samples. Advice is given in Haeussler et al. (2013MNRAS.430..330H and 2022) on what constraints to use for such a selection. E.g. objects along the edge of the allowed parameter space should be considers and non-free fits, and their values should be avoided. As such a selection will depend on the science case (clean vs large sample), we make no attempt to solve this issue universally for all science cases. In Haeussler 2013 and 2022, we use the following constraints, and we advice user to avoid values CLOSE to those (e.g. 0.205<n_galfit<7.95, for a 0.2<n<8 constraint) for single-sersic fits (checked for EACH BAND): - 0.2 < n < 8 - 0.3 < re < 400 - 0.001 < q < 1.0 - 0 < mag < 40 - mag_{best-5+offset < mag < mag}best+5+offset (within 5 mags of starting value of the fit) with offset (ugrizYJHK) being [1.6562516, 0.93480262, -0.035029945, -0.55207007, -0.77597345, -0.84817872, -0.95977787, -1.1561573, -1.1386097] - flag_galfit == 2 (fit needs to have finished) for B/D fits (checked for EACH BAND): - 0.2 < n_bulge < 8 - X and Y position within 0.5*re_galfitr of single-sersic position - 0.3 < re_bulge < 400 - 0.3 < re_disk < 400 - 0.001 < q_bulge < 1.0 - 0.001 < q_disk < 1.0 - 0 < mag_bulge < 40 - 0 < mag_disk < 40 - mag_galfitband[i]+2.5alog10(2)-5 < mag_bulge[i] < mag_galfitband[i]+2.5alog10(2)+5 (within 5 magnitudes of starting value of the fit, e.g. half the flux of the single-sersic fit) - mag_galfitband[i]+2.5alog10(2)-5 < mag_disk[i] < mag_galfitband[i]+2.5alog10(2)+5 (within 5 magnitudes of starting value of the fit, e.g. half the flux of the single-sersic fit) - flag_galfitbd == 2 (fit needs to have finished)

(4 data files).