| We present new JWST/NIRSpec IFU observations of the core of a galaxy protocluster hosting a massive, dusty star-forming galaxy (DSFG). Previous work using VLT/MUSE and high-resolution ALMA imaging had already shown CGM-scale emission in this system, such as a bright Lyman-α blob, and an enigmatic 15 kpc-long [CII] 158µm plume, respectively.The new data reveals new extended nebulae surrounding the system as well as multiple compact satellites. A remarkable case is that of two bright [O III] λ5007 nebulae at each side of the DSFG disk along its minor axis. One nebula (O3-N) sits at the base of the [C II] plume, showing a clear FWHM~1300 km/s broad and blueshifted component, suggesting an outflow origin for the [C II] plume. The other nebula (O3-S) stretches over ~10 kpc, and has a velocity gradient that spans 800 km/s, but no evidence of a broad component. O3-S thus resembles the tidal tail left by a companion galaxy. Both sources, however, seem to be powered at least partially by an active galactic nucleus (AGN), as suggested by strong line ratio diagnostics and the detection of high ionization species such as He II and [Ne V]. We interpret this as O3-S being externally irradiated by an obscured or faded AGN, akin to the famous Hanny’s Voorwerp object in the local Universe. Moreover, our deep Hα map shows widespread star formation in the form of low-mass companions and diffuse emission, shedding light on the origins of the Lyman-α blob. These results showcase the complexity of the multiphase CGM in a highly active environment at a very early epoch. |
