Gemini Follow-up of two massive HI clouds discovered with the Australian Square Kilometer Array Pathfinder

Abstract

Using the Gemini Multi Object Spectrograph (GMOS) we search for optical counterparts of two massive (~10^9 solar masses) neutral hydrogen clouds near the spiral galaxy IC 5270, located in the outskirts of the IC 1459 group. These two HI clouds were recently discovered using the Australian Square Kilometer Array Pathfinder (ASKAP). Two low surface brightness optical counterparts to one of these HI clouds are identified in the new Gemini data that reaches down to magnitudes of ~27.5 mag in the g-band. The observed HI mass to light ratio derived with these new data, M_(HI)/L_g =242, is among the highest reported to date. We are also able to rule out that the two HI clouds are dwarf companions of IC 5270. Tidal interactions and ram pressure stripping are plausible explanations for the physical origin of these two clouds.