Speaker
Description
In the ΛCDM cosmological framework, dark matter (DM) halos represent the building blocks for galactic structures. Galaxies are expected to form stars from their gas reservoirs in the gravitational potential of these DM halos, which are predicted to be more common with decreasing mass. But not all DM halos effectively convert this gas into stars, forming a galaxy. Gas may accumulate without undergoing star formation activity. Such galaxies are expected to be nearly dark due to the scarcity of stars, and in some cases, be completely dark due to the absence of stars. Such objects are named “dark galaxies” and their existence may contribute to solving the so-called “Missing Satellite
Problem, which has puzzled astronomers for decades.
Since dark galaxies contain a modest amount of cold neutral hydrogen (HI) gas, they are detectable with radio telescopes. We have collected deep imaging data with OmegaCAM@VST of five isolated “dark galaxies” candidates identified in the WALLABY ASKAP pilot survey to reveal the optical counterpart of these extreme objects. This will allow us to place a limit on how “dark” these galaxies truly are, thereby helping to clarify the nature of the HI emission and studying the structural properties of the mysterious class of galaxies.
In this talk, I will present recent results obtained by combining information on HI data with deep photometry from VST images.