We present the discovery of HLock01-LAB , a luminous and large Ly \alpha nebula at z = 3.326 .
Medium-band imaging and long-slit spectroscopic observations with the Gran Telescopio Canarias reveal extended emission in the Ly \alpha 1215Å , C iv 1550Å , and He ii 1640Å lines over \sim 100 kpc , and a total luminosity L _ { Ly \alpha } = ( 6.4 \pm 0.1 ) \times 10 ^ { 44 } erg s ^ { -1 } .
HLock01-LAB presents an elongated morphology aligned with two faint radio sources contained within the central \sim 8 kpc of the nebula .
The radio structures are consistent to be faint radio jets or lobes of a central galaxy , whose spectrum shows nebular emission characteristic of a type-II active galactic nucleus ( AGN ) .
The continuum emission of the AGN at short wavelengths is , however , likely dominated by stellar emission of the host galaxy , for which we derive a stellar mass M _ { * } \simeq 2.3 \times 10 ^ { 11 } M _ { \odot } .
Our kinematic analysis shows that the ionized gas is perturbed almost exclusively in the inner region between the radio structures , probably as a consequence of jet-gas interactions , whereas in the outer regions the ionized gas appears more quiescent .
The detection of extended emission in C iv and C iii ] indicates that the gas within the nebula is not primordial .
Feedback may have enriched the halo at at least 50 kpc from the nuclear region .
Using rest-frame UV emission-line diagnostics , we find that the gas in the nebula is likely heated by the AGN .
Nevertheless , at the center of the nebula we find extreme emission line ratios of Ly \alpha /C iv \sim 60 and Ly \alpha /He ii \sim 80 , one of the highest values measured to date , and well above the standard values of photoionization models ( Ly \alpha /He ii \sim 30 for case B photoionization ) .
Our data suggest that jet-induced shocks are likely responsible for the increase of the electron temperature and , thus , the observed Ly \alpha enhancement in the center of the nebula .
This scenario is further supported by the presence of radio structures and perturbed kinematics in this region .
The large Ly \alpha luminosity in HLock01-LAB is likely due to a combination of AGN photoionization and jet-induced shocks , highlighting the diversity of sources of energy powering Ly \alpha nebulae .
Future follow-up observations of HLock01-LAB will help in revealing in more detail the excitation conditions of the gas induced by jets and investigate the underlying cooling and feedback processes in this unique object .