In order to construct a sample of ultra-luminous infrared galaxies ( ULIRGs , with infrared luminosity , L _ { IR } > 10 ^ { 12 } L _ { \odot } ) at 0.5 < z < 1 , we are conducting an optical follow-up program for bright 90- \mu m FIR sources with a faint optical ( i < 20 mag ) counterpart selected in the AKARI Far-Infrared Surveyor ( FIS ) Bright Source catalog ( Ver.2 ) .
AKARI-FIS-V2 J0916248+073034 , identified as a ULIRG at z = 0.49 in the spectroscopic follow-up observation , indicates signatures of an extremely strong outflow in its emission line profiles .
Its [ O iii ] 5007Å emission line shows FWHM of 1830 km s ^ { -1 } and velocity shift of -770 km s ^ { -1 } in relative to the stellar absorption lines .
Furthermore , low-ionization [ O ii ] 3726Å 3729Å doublet also shows large FWHM of 910 km s ^ { -1 } and velocity shift of -380 km s ^ { -1 } .
After the removal of an unresolved nuclear component , the long-slit spectroscopy 2D image possibly shows that the outflow extends to radius of 4 kpc .
The mass outflow and energy ejection rates are estimated to be 500 M _ { \odot } yr ^ { -1 } and 4 \times 10 ^ { 44 } erg s ^ { -1 } , respectively , which imply that the outflow is among the most powerful ones observed in ULIRGs and QSOs at 0.3 < z < 1.6 .
The co-existence of the strong outflow and intense star formation ( star formation rate of 990 M _ { \odot } yr ^ { -1 } ) indicates that the feedback of the strong outflow has not severely affect the star-forming region of the galaxy .