Using the Atacama Large Millimeter/submillimeter Array ( ALMA ) , we report high angular-resolution observations of the redshift z =3.63 galaxy H -ATLAS J083051.0+013224 ( G09v1.97 ) , one of the most luminous strongly lensed galaxies discovered by the Herschel -Astrophysical Terahertz Large Area Survey ( H -ATLAS ) .
We present 0 \aas@@fstack { \prime \prime } 2–0 \aas@@fstack { \prime \prime } 4 resolution images of the rest-frame 188 and 419 \mu m dust continuum and the { \mathrm { CO } } ( 6 \text { - - } 5 ) , H 2 O ( 2 _ { 11 } \text { - - } 2 _ { 02 } ) , and J _ { \mathrm { up } } = 2 H _ { 2 } O ^ { + } line emission .
We also report the detection of H _ { 2 } ^ { 18 } O ( 2 _ { 11 } \text { - - } 2 _ { 02 } ) in this source .
The dust continuum and molecular gas emission are resolved into a nearly complete \sim 1 \aas@@fstack { \prime \prime } 5 diameter Einstein ring plus a weaker image in the center , which is caused by a special dual deflector lensing configuration .
The observed line profiles of the { \mathrm { CO } } ( 6 \text { - - } 5 ) , H 2 O ( 2 _ { 11 } \text { - - } 2 _ { 02 } ) , and J _ { \mathrm { up } } = 2 H _ { 2 } O ^ { + } lines are strikingly similar .
In the source plane , we reconstruct the dust continuum images and the spectral cubes of the CO , H 2 O , and H _ { 2 } O ^ { + } line emission at sub-kiloparsec scales .
The reconstructed dust emission in the source plane is dominated by a compact disk with an effective radius of 0.7 \pm 0.1 kpc plus an overlapping extended disk with a radius twice as large .
While the average magnification for the dust continuum is \mu \sim 10–11 , the magnification of the line emission varies from 5 to 22 across different velocity components .
The line emission of { \mathrm { CO } } ( 6 \text { - - } 5 ) , H 2 O ( 2 _ { 11 } \text { - - } 2 _ { 02 } ) , and H _ { 2 } O ^ { + } have similar spatial and kinematic distributions .
The molecular gas and dust content reveal that G09v1.97 is a gas-rich major merger in its pre-coalescence phase , with a total molecular gas mass of \sim 10 ^ { 11 } M _ { \odot } .
Both of the merging companions are intrinsically ultra-luminous infrared galaxies ( ULIRGs ) with infrared luminosities L _ { \mathrm { IR } } reaching \gtrsim 4 \times 10 ^ { 12 } L _ { \odot } , and the total L _ { \mathrm { IR } } of G09v1.97 is ( 1.4 \pm 0.7 ) \times 10 ^ { 13 } L _ { \odot } .
The approaching southern galaxy ( dominating from V = - 400 to - 150 km s ^ { -1 } relative to the systemic velocity ) shows no obvious kinematic structure with a semi-major half-light radius of a _ { \mathrm { s } } = 0.4 kpc , while the receding galaxy ( 0 to 350 km s ^ { -1 } ) resembles an a _ { \mathrm { s } } = 1.2 kpc rotating disk .
The two galaxies are separated by a projected distance of 1.3 kpc , bridged by weak line emission ( - 150 to 0 km s ^ { -1 } ) that is co-spatially located with the cold dust emission peak , suggesting a large amount of cold interstellar medium ( ISM ) in the interacting region .
As one of the most luminous star-forming dusty high-redshift galaxies , G09v1.97 is an exceptional source for understanding the ISM in gas-rich starbursting major merging systems at high redshift .