Scientific Seminars

Compact groups of galaxies: small, dense, elusive

Emanuela Pompei
ESO

2007-09-19    14:00    Brera -

Compact groups of galaxies became known to astronomers during the 80's, thanks to eyeball searches of photographic plates. Their high surface density and their low velocity dispersion, coupled with isolation on the sky made groups objects so peculiar that very few scientists believed in their physical reality. Today compact groups have been proved to be physically bound objects, with a variety of structures; however the three fundamental questions about them remain still open: - when and how do groups form? - how do they evolve? - what is their relation with larger scale structures on the sky? Attempting to find an answer to these questions, we performed two extended surveys of compact groups in the southern emisphere, one in the nearby Universe and another at higher redshift. During the talk we will present the results obtained so far in these surveys and how these results can help answering the open questions about compact groups.