The central region of the Fornax cluster -- I. A catalog and photometric properties of galaxies in selected CCD fields

TL;DR

This paper provides a detailed photometric catalog of galaxies in the Fornax cluster's central region, analyzing their properties and confirming known relations while clarifying the distribution of dwarf galaxies.

Contribution

It presents a new, extensive V and I photometric catalog of Fornax galaxies, including surface brightness profiles and analysis of dwarf galaxy distribution and properties.

Findings

Confirmed that Fornax dwarf galaxies follow similar brightness-magnitude relations as Local Group dwarfs.

Ruled out an excess of dwarf galaxies around NGC 1399, attributing observed density to a background cluster.

Added four new dwarf galaxies to existing catalogs.

Abstract

We present a photometric catalog (based on V and I photometry) of galaxies in the central regions of the Fornax galaxy cluster. Our 11 CCD fields cover 0.17 degrees in total. The limiting surface brightness is around 24 mag arsec^-2, similar to that of Ferguson's (1989, AJ 98, 367) catalog, whereas our limiting total magnitude is around V = 22 mag, about two magnitudes fainter. It is the surface brightness limit, however, that prevents us from detecting the counterparts of the faintest Local Group dwarf spheroidals. The photometric properties of all objects are presented as a catalog. The properties and fit parameters of the surface brightness profiles for a sub-sample are presented as a second catalog (both catalogs are available in electronic form at the CDS). We can only add 4 new dwarf galaxies to Ferguson's catalog. However, we confirm that the dwarf galaxies in Fornax follow a similar surface brightness-magnitude relation as the Local Group dwarfs. They also follow the color (metallicity) - relation seen in other galaxy clusters. A formerly suspected excess of dwarf galaxies surrounding the central cD galaxy NGC 1399 can finally be ruled out. An enhanced density of objects around NGC 1399 can indeed be seen, but it appears displaced with respect to the central galaxy and is identified as a background cluster at z = 0.11 in Paper II of these series, which will discuss spectroscopic results for our sample.