Abstract

Invited Talk - Splinter DwarfGalaxies

Monday, 09 September 2024, 16:20   (S24)

Hierarchical merging events at the smallest scales

Elena Sacchi
Leibniz Institut für Astrophysik Potsdam (AIP)

The current cosmological paradigm predicts that galaxies form by means of a hierarchical merging process irrespective of the galaxy mass, making the realm of dwarf galaxies particularly interesting (though observationally challenging) to test the smallest scales. In this context, I will introduce the results of the Smallest Scale of Hierarchy (SSH) survey, aimed at looking for signatures of recent merging events in a sample of 45 isolated star-forming local (< 10 Mpc) dwarf galaxies (-11 < M_B < -18) resolved into stars by deep wide-field LBT imaging. Limiting the survey to resolved galaxy only allows us to discriminate between young stars, that trace the (typically) strongly asymmetric distribution of star forming regions, and old stars, specifically Red Giant Branch (RBG) stars (at least 1-2 Gyr old), whose distribution should reliably trace the galaxy gravitational potential and the possible disturbances induced by interactions with satellites. I will discuss the most evident cases in which we found clear evidence for a merging with smaller satellites, as well as the hydrodynamical modeling and HST follow-ups of some of the most interesting galaxies. I will finally compare these results with the current theoretical predictions for galaxy formation within the LCDM cosmological framework.