Unveiling a Rich System of Faint Dwarf Galaxies in the Next Generation Fornax Survey

TL;DR

This paper reports the discovery of 158 new faint dwarf galaxies in the Fornax cluster, including ultra-diffuse and extremely low surface brightness types, using deep multi-band imaging, revealing their properties, distribution, and clustering.

Contribution

First comprehensive detection and analysis of faint dwarf galaxies in the Fornax cluster using deep multi-band imaging, including ultra-diffuse and ultra-faint types, with insights into their distribution and clustering.

Findings

Discovered 158 new dwarf galaxies in Fornax cluster.

Confirmed presence of ultra-diffuse galaxies in Fornax.

Identified clustering of dwarf galaxies on scales below 100 kpc.

Abstract

We report the discovery of 158 previously undetected dwarf galaxies in the Fornax cluster central regions using a deep coadded $u, g$ and $i$-band image obtained with the DECam wide-field camera mounted on the 4-meter Blanco telescope at the Cerro Tololo Interamerican Observatory as part of the {\it Next Generation Fornax Survey} (NGFS). The new dwarf galaxies have quasi-exponential light profiles, effective radii $0.1\!<\!r_e\!<\!2.8$ kpc and average effective surface brightness values $22.0\!<\!\mu_i\!<\!28.0$ mag arcsec$^{-2}$. We confirm the existence of ultra-diffuse galaxies (UDGs) in the Fornax core regions that resemble counterparts recently discovered in the Virgo and Coma galaxy clusters.~We also find extremely low surface brightness NGFS dwarfs, which are several magnitudes fainter than the classical UDGs. The faintest dwarf candidate in our NGFS sample has an absolute magnitude of $M_i\!=\!-8.0$\,mag. The nucleation fraction of the NGFS dwarf galaxy sample appears to decrease as a function of their total luminosity, reaching from a nucleation fraction of $>\!75\%$ at luminosities brighter than $M_i\!\simeq\!-15.0$ mag to $0\%$ at luminosities fainter than $M_i\!\simeq\!-10.0$ mag. The two-point correlation function analysis of the NGFS dwarf sample shows an excess on length scales below $\sim\!100$ kpc, pointing to the clustering of dwarf galaxies in the Fornax cluster core.