CO, H2O, H2O+ line and dust emission in a z = 3.63 strongly lensed starburst merger at sub-kiloparsec scales
Abstract
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.″2-0.″4 resolution images of the rest-frame 188 and 419 μm dust continuum and the CO(6-5), H2O(211-202), and Jup = 2 H2O+ line emission. We also report the detection of H2O(211-202) in this source. The dust continuum and molecular gas emission are resolved into a nearly complete ∼1.″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 CO(6-5), H2O(211-202), and Jup = 2 H2O+ lines are strikingly similar. In the source plane, we reconstruct the dust continuum images and the spectral cubes of the CO, H2O, and H2O+ 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 ± 0.1 kpc plus an overlapping extended disk with a radius twice as large. While the average magnification for the dust continuum is μ ∼ 10-11, the magnification of the line emission varies from 5 to 22 across different velocity components. The line emission of CO(6-5), H2O(211-202), and H2O+ 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 ∼1011 M⊙. Both of the merging companions are intrinsically ultra-luminous infrared galaxies (ULIRGs) with infrared luminosities LIR reaching ≳4 × 1012 L⊙, and the total LIR of G09v1.97 is (1.4 ± 0.7)×1013 L⊙. 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 as = 0.4 kpc, while the receding galaxy (0 to 350 km s-1) resembles an as = 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.
Reduced images and datacubes are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A138- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 2019
- DOI:
- 10.1051/0004-6361/201833876
- arXiv:
- arXiv:1903.00273
- Bibcode:
- 2019A&A...624A.138Y
- Keywords:
-
- galaxies: high-redshift;
- galaxies: ISM;
- gravitational lensing: strong;
- submillimeter: galaxies;
- radio lines: ISM;
- ISM: molecules;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 19 pages, 12 figures, and 4-page appendix, A&