Abstract:
Starbursts are rarely found in compact groups of galaxies. SQ-A, a starburst in the intra-group medium (IGrM) of the famous compact group Stephan's Quintet (SQ), is quite unique. Its triggering mechanism has been an enigma ever since its discovery. If SQ-A is triggered by a high-speed collision between an intruder galaxy and the IGrM, why does the same collision cause a star-formation (SF) suppression rather than starburst in the SQ's large scale shock (~40 kpc)? In this paper we aim to solve this puzzle using new ALMA and VLA data. Our results can have far-reaching implications for studies of interacting galaxy systems (mergers, groups, clusters) since the collision triggered SF plays an important role in these systems.
