ALBERT

Description: We present Multi Unit Spectroscopic Explorer (MUSE) integral field unit spectroscopic observations of the ~150 kpc Lyα halo around the z  = 4.1 radio galaxy TN J1338–1942. This 9-h observation maps the full two-dimensional kinematics of the Lyα emission across the halo, which shows a velocity gradient of v ~ 700 km s –1 across 150 kpc in projection, and also identified two absorption systems associated with the Lyα emission from the radio galaxy. Both absorbers have high covering fractions (~1) spanning the full ~150 80 kpc 2 extent of the halo. The stronger and more blueshifted absorber ( v ~ –1200 km s –1 from the systemic) has dynamics that mirror that of the underlying halo emission and we suggest that this high column material ( n (H i ) ~ 10 19.4  cm –2 ), which is also seen in C iv absorption, represents an outflowing shell that has been driven by the active galactic nuclei (AGN) or the star formation within the galaxy. The weaker ( n (H i ) ~ 10 14  cm –2 ) and less blueshifted ( v ~ –500 km s –1 ) absorber most likely represents material in the cavity between the outflowing shell and the Lyα halo. We estimate that the mass in the shell must be ~10 10  M – a significant fraction of the interstellar medium from a galaxy at z  = 4. The large scales of these coherent structures illustrate the potentially powerful influence of AGN feedback on the distribution and energetics of material in their surroundings. Indeed, the discovery of high-velocity (~1000 km s –1 ), group-halo-scale (i.e. 〉150 kpc) and mass-loaded winds in the vicinity of the central radio source is in agreement with the requirements of models that invoke AGN-driven outflows to regulate star formation and black hole growth in massive galaxies.