Two-dimensional multi-component photometric decomposition of CALIFA galaxies

Abstract

We present a two-dimensional multi-component photometric decomposition of 404 galaxies from the Calar Alto Legacy Integral Field Area Data Release 3 (CALIFA-DR3). They represent all possible galaxies with no clear signs of interaction and not strongly inclined in the final CALIFA data release. Galaxies are modelled in the g, r, and i Sloan Digital Sky Survey (SDSS) images including, when appropriate, a nuclear point source, bulge, bar, and an exponential or broken disc component. We use a human-supervised approach to determine the optimal number of structures to be included in the fit. The dataset, including the photometric parameters of the CALIFA sample, is released together with statistical errors and a visual analysis of the quality of each fit. The analysis of the photometric components reveals a clear segregation of the structural composition of galaxies with stellar mass. At high masses (log(M ⋆ /M ⊙ ) > 11), the galaxy population is dominated by galaxies modelled with a single Sérsic or a bulge+disc with a bulge-tototal (B/T ) luminosity ratio B/T > 0.2. At intermediate masses (9.5 < log(M ⋆ /M ⊙ ) < 11), galaxies described with bulge+disc but B/T < 0.2 are preponderant, whereas, at the low mass end (log(M ⋆ /M ⊙ ) < 9.5), the prevailing population is constituted by galaxies modelled with either pure discs or nuclear point sources+discs (i.e., no discernible bulge). We obtain that 57% of the volume corrected sample of disc galaxies in the CALIFA sample host a bar. This bar fraction shows a significant drop with increasing galaxy mass in the range 9.5 < log(M ⋆ /M ⊙ ) < 11.5. The analyses of the extended multi-component radial profile result in a volume-corrected distribution of 62%, 28%, and 10% for the so-called Type I (pure exponential), Type II (down-bending), and Type III (up-bending) disc profiles, respectively. These fractions are in discordance with previous findings. We argue that the different methodologies used to detect the breaks are the main cause for these differences.

Star Formation in the Local Universe from the CALIFA Sample. II. Activation and Quenching Mechanisms in Bulges, Bars, and Disks

“…Galaxies meeting any of the following criteria were excluded: (1) if they are forming a pair, are forming an interacting system, or have a heavily distorted morphology; and (2) if they are highly inclined galaxies, as the projection effects can affect the results (typically i > 70°). More details about the sample selection are given in Mendez-Abreu et al (2017). A total of 204 galaxies were excluded in this way.…”

“…We use the structural parameters derived for the CALIFA galaxies in Mendez-Abreu et al (2017). These values were obtained by applying the 2D photometric decomposition code GASP2D (Méndez-Abreu et al 2008 over the g-, r-, and i-band images from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7, Abazajian et al 2009).…”

“…This code allows the simultaneous fitting of different galaxy structures such as nuclear point sources, bulges, bars, and disks (including breaks). The reader is referred to Mendez-Abreu et al (2017) for more details about the methodology of the fitting algorithm.…”

No evidence for small disk-like bulges in a sample of late-type spirals

“…We modeled the point spread function (PSF) with a circular Moffat profile (Moffat 1969;Trujillo et al 2001), which is a reliable approximation for photometric decomposition of nearby galaxies in SDSS images (Méndez-Abreu et al 2017), and derived its parameters fitting 5 unsaturated stars with the IRAF task imexamine before trimming the image (Table 2).…”

“…In this context, the bulge is photometrically defined as the extra component dominating the galaxy light above the surfaceluca.costantin@studenti.unipd.it brightness profile of the disk extrapolated in the inner regions of the galaxy. The bulge surface brightness is usually fitted with a Sérsic law spanning a large range of profile shapes, whereas the disk surface brightness is usually fitted with an exponential law (Andredakis 1998;Prieto et al 2001;Aguerri et al 2005;Méndez-Abreu et al 2017). …”