XMM-Newton first-light observations of the Hickson galaxy group 16
- Authors: Turner, M.; Reeves, J.; Ponman, T.; Arnaud, M.; Barbera, M.; Bennie, P.; Boer, M.; Briel, U.; Butler, I.; Clavel, J.; Dhez, P.; Cordova, F.; Dos Santos, S.; Ferrando, P.; Ghizzardi, S.; Goodall, C.; Griffiths, R.; Hochedez, J.; Holland, A.; Jansen, F.; Kendziorra, E.; Lagostina, A.; Laine, R.; La Palombara, N.; Lortholary, M.; Mason, K.; Molendi, S.; Pigot, C.; Priedhorsky, W.; Reppin, C.; Rothenflug, R.; Salvetat, P.; Sauvageot, J.; Schmitt, D.; Sembay, S.; Short, A.; Strüder, L.; Trifoglio, M.; Trümper, J.; Vercellone, S.; Vigroux, L.; Villa, G.; Ward, M.
- Publication year: 2001
- Type: Articolo in rivista (Articolo in rivista)
- Key words: Galaxies: active; Galaxies: starburst; X-rays: galaxies; Space and Planetary Science
- OA Link: http://hdl.handle.net/10447/214953
Abstract
This paper presents the XMM-Newton first-light observations of the Hickson-16 compact group of galaxies. Groups are possibly the oldest large-scale structures in the Universe, pre-dating clusters of galaxies, and are highly evolved. This group of small galaxies, at a redshift of 0.0132 (or 80 Mpc) is exceptional in the having the highest concentration of starburst or AGN activity in the nearby Universe. So it is a veritable laboratory for the study of the relationship between galaxy interactions and nuclear activity. Previous optical emission line studies indicated a strong ionising continuum in the galaxies, but its origin, whether from starbursts, or AGN, was unclear. Combined imaging and spectroscopy with the EPIC X-ray CCDs unequivocally reveals a heavily obscured AGN and a separately identified thermal (starburst) plasma, in NGC 835, NGC 833, & NGC 839. NGC 838 shows only starburst thermal emission. Starbursts and AGN can evidently coexist in members of this highly evolved system of merged and merging galaxies, implying a high probability for the formation of AGN as well as starbursts in post-merger galaxies.