MUSE sneaks a peek at extreme ram-pressure stripping events - IV.
  Hydrodynamic and gravitational interactions in the Blue Infalling Group
  We report new wide-field (~ 4 x 4 square arcmin) MUSE observations of the
Blue Infalling Group (BIG), a compact group of galaxies located at a projected
distance of ~ 150 kpc from the X-Ray centre of the A1367 cluster at z = 0.021.
Our MUSE observations map in detail the extended ionized gas, primarily traced
by H$\alpha$ emission, in between the members of the group. The gas morphology
and its kinematics appear consistent with a tidal origin due to galaxy
encounters, as also supported by the disturbed kinematics visible in one of the
group members and the presence of tidal dwarf systems. A diffuse tail extending
in the direction opposite to the cluster centre is also detected, hinting at a
global ram-pressure stripping of the intra-group material as BIG falls inside
A1367. Based on the analysis of spatially-resolved emission line maps, we
identify multiple ionization mechanisms for the diffuse gas filaments,
including in situ photoionization from embedded HII regions and shocks.
Combining spatially resolved kinematics and line ratios, we rule out the
association of the most massive galaxy, CGCG097-120, with the group as this
system appears to be decoupled from the intragroup medium and subject to strong
ram pressure as it falls into A1367. Through our new analysis, we conclude that
BIG is shaped by pre-processing produced by gravitational interactions in the
local group environment combined with ram pressure stripping by the global
cluster halo.
