We report ground-based follow-up observations of the exceptional source , ID 141 , one the brightest sources detected so far in the H -ATLAS cosmological survey .
ID 141 was observed using the IRAM 30-meter telescope and Plateau de Bure interferometer ( PdBI ) , the Submillimeter Array ( SMA ) and the Atacama Pathfinder Experiment ( APEX ) submillimeter telescope to measure the dust continuum and emission lines of the main isotope of carbon monoxide and carbon ( [ C I ] and [ C II ] ) .
The detection of strong CO emission lines with the PdBI confirms that ID 141 is at high redshift ( z = 4.243 \pm 0.001 ) .
The strength of the continuum and emission lines suggests that ID 141 is gravitationally lensed .
The width ( \Delta V _ { FWHM } \sim 800 km s ^ { -1 } ) and asymmetric profiles of the CO and carbon lines indicate orbital motion in a disc or a merger .
The properties derived for ID 141 are compatible with a ultraluminous ( L _ { FIR } \sim 8.5 \pm 0.3 \times 10 ^ { 13 } \mu _ { L } ^ { -1 } L _ { \odot } , where \mu _ { L } is the amplification factor ) , dense ( n \approx 10 ^ { 4 } cm ^ { -3 } ) and warm ( T _ { kin } \approx 40 K ) starburst galaxy , with an estimated star-formation rate of ( 0.7 to 1.7 ) \times 10 ^ { 4 } \mu _ { L } ^ { -1 } M _ { \odot } / yr .
The carbon emission lines indicate a dense ( n \approx 10 ^ { 4 } cm ^ { -3 } ) Photo-Dominated Region , illuminated by a far-UV radiation field a few thousand times more intense than that in our Galaxy .
In conclusion , the physical properties of the high- z galaxy ID 141 are remarkably similar to those of local ultraluminous infrared galaxies .