The Fornax Deep Survey with the VST

Abstract

Context. The Fornax Deep Survey (FDS), an imaging survey in the u , g , r , and i -bands, has a supreme resolution and image depth compared to the previous spatially complete Fornax Cluster Catalog (FCC). Our new data allows us to study the galaxies down to r -band magnitude m r ≈ 21 mag (M r ≈ −10.5 mag), which opens a new parameter regime to investigate the evolution of dwarf galaxies in the cluster environment. After the Virgo cluster, Fornax is the second nearest galaxy cluster to us, and with its different mass and evolutionary state, it provides a valuable comparison that makes it possible to understand the various evolutionary effects on galaxies and galaxy clusters. These data provide an important legacy dataset to study the Fornax cluster. Aims. We aim to present the Fornax Deep Survey (FDS) dwarf galaxy catalog, focusing on explaining the data reduction and calibrations, assessing the quality of the data, and describing the methods used for defining the cluster memberships and first order morphological classifications for the catalog objects. We also describe the main scientific questions that will be addressed based on the catalog. This catalog will also be invaluable for future follow-up studies of the Fornax cluster dwarf galaxies. Methods. As a first step we used the SExtractor fine-tuned for dwarf galaxy detection, to find galaxies from the FDS data, covering a 26 deg 2 area of the main cluster up to its virial radius, and the area around the Fornax A substructure. We made 2D-decompositions of the identified galaxies using GALFIT, measure the aperture colors, and the basic morphological parameters like concentration and residual flux fraction. We used color-magnitude, luminosity-radius and luminosity-concentration relations to separate the cluster galaxies from the background galaxies. We then divided the cluster galaxies into early-and late-type galaxies according to their morphology and gave first order morphological classifications using a combination of visual and parametric classifications. Results. Our final catalog includes 14 095 galaxies. We classify 590 galaxies as being likely Fornax cluster galaxies, of which 564 are dwarfs (M r > −18.5 mag) consisting our Fornax dwarf catalog. Of the cluster dwarfs we classify 470 as early-types, and 94 as late-type galaxies. Our final catalog reaches its 50% completeness limit at magnitude M r = −10.5 mag and surface brightness µ e,r = 26 mag arcsec −2 , which is approximately three magnitudes deeper than the FCC. Based on previous works and comparison with a spectroscopically confirmed subsample, we estimate that our final Fornax dwarf galaxy catalog has 10% contamination from the background objects.The catalogs are only at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/620/A165Article published by EDP Sciences A165, page 1 of 31 A&A 620, A165 (2018)

Neutral hydrogen gas within and around NGC 1316

“…Future data with better frequency resolution will allow us to better characterise their morphology and kinematics. Figure 2 shows primary-beam-corrected, constant-columndensity H i contours overlaid on an r-band optical image from the Fornax Deep Survey (Iodice et al 2016(Iodice et al , 2017Venhola et al 2018) . Figure 3 shows the H i velocity field.…”

Observational properties of ultra-diffuse galaxies in low-density environments: field UDGs are predominantly blue and star forming

“…Our model colour distributions for the mock UDG catalogues. The data we fit are from Venhola et al (2018) and correspond to late-type (small blue points) and early-type (small red points) dwarf galaxies in the Fornax cluster. We fit simple linear models (uninterrupted coloured lines) and their 1σ uncertainties (dashed lines) after clipping outliers at 3σ.…”

A spectroscopic census of the Fornax cluster and beyond: preparing for next generation surveys

“…The input photometry is derived from the FDS (Iodice et al 2016), with catalogues of resolved objects provided by Venhola et al (2018). We impose a magnitude limit of g ≤ 19.5 to be generally consistent with the observations with the same instrument by Drinkwater et al (2000a).…”

“…The Fornax cluster has recently been at the centre of several major observing programmes over a wide range of wavelengths. This includes deep optical imaging (Iodice et al 2016;Venhola et al 2018;Eigenthaler et al 2018), optical integral field unit (IFU) observations of selected targets (Scott et al 2014;Mentz et al 2016;Sarzi et al 2018), ALMA observations (Zabel et al 2019;Morokuma-Matsui et al 2019), far-infrared Herschel imaging (Davies et al 2013) and, at radio wavelengths, a survey carried out with the Australia Telescope Compact Array (ATCA; Lee-Waddell et al 2018).…”

“…Example of an extended galaxy with multiple spectra sufficiently far apart from each other that they are not identified as duplicate observations of the same galaxy. The white square indicates the position of the object from theVenhola et al (2018) photometry catalogue, while the white circles are the coordinates of the three spectra. Each circle has a 2 ′′ radius, and the square is 4 ′′ on a side.…”