The Next Generation Fornax Survey (NGFS). II. The Central Dwarf Galaxy Population

We present a photometric study of the dwarf galaxy population in the core region (less than or similar to r(vir)/4) of the Fornax galaxy cluster based on deep u' g' i' photometry from the Next Generation Fornax Cluster Survey.. All imaging data were obtained with the Dark Energy Camera mounted on the 4 m Blanco telescope at the Cerro Tololo Interamerican Observatory. We identify 258 dwarf galaxy candidates with luminosities -17 less than or similar to. M-g' less than or similar to - 8 mag, corresponding to typical stellar masses of 9.5 greater than or similar to log M-*/M-circle dot greater than or similar to 5.5, reaching similar to 3 mag deeper in point- source luminosity and similar to 4 mag deeper in surface brightness sensitivity compared to the classic Fornax Cluster Catalog. Morphological analysis shows that the dwarf galaxy surface-brightness profiles are well represented by single- component Sersic models with average Sersic indices of < n > u' , g', i' =( 0.78-0.83) +/- 0.02 and average effective radii of < r(e)> u', g', i' = ( 0.67-0.70) +/- 0.02 kpc. Color-magnitude relations indicate a flattening of the galaxy red sequence at faint galaxy luminosities, similar to the one recently discovered in the Virgo cluster. A comparison with population synthesis models and the galaxy mass-metallicity relation reveals that the average faint dwarf galaxy is likely older than similar to 5 Gyr. We study galaxy scaling relations between stellar mass, effective radius, and stellar mass surface density over a stellar mass range covering six orders of magnitude. We find that over the sampled stellar mass range several distinct mechanisms of galaxy mass assembly can be identified: ( 1) dwarf galaxies assemble mass inside the half-mass radius up to log M-* approximate to 8.0, ( 2) isometric mass assembly occurs in the range 8.0 less than or similar to logM(*)/M-circle dot less than or similar to 10.5, and ( 3) massive galaxies assemble stellar mass predominantly in their halos at log M-* approximate to 10.5 and above.