Astronomy and Astrophysics, volume 624A, 138-138 (2019/4-1)
CO, H2O, H2O+ line and dust emission in a z = 3.63 strongly lensed starburst merger at sub-kiloparsec scales.
YANG C., GAVAZZI R., BEELEN A., COX P., OMONT A., LEHNERT M.D., GAO Y., IVISON R.J., SWINBANK A.M., BARCOS-MUNOZ L., NERI R., COORAY A., DYE S., EALES S., FU H., GONZALEZ-ALFONSO E., IBAR E., MICHALOWSKI M.J., NAYYERI H., NEGRELLO M., NIGHTINGALE J., PEREZ-FOURNON I., RIECHERS D.A., SMAIL I. and VAN DER WERF P.
Abstract (from CDS):
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=2H2O+ 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=2H2O+ 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±0.1kpc 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 ∼1011M☉. Both of the merging companions are intrinsically ultra-luminous infrared galaxies (ULIRGs) with infrared luminosities LIR reaching ≥4x1012L☉, and the total LIR of G09v1.97 is (1.4±0.7)x1013L☉. The approaching southern galaxy (dominating from V=-400 to -150km/s relative to the systemic velocity) shows no obvious kinematic structure with a semi-major half-light radius of as=0.4kpc, while the receding galaxy (0 to 350km/s) resembles an as=1.2kpc rotating disk. The two galaxies are separated by a projected distance of 1.3kpc, bridged by weak line emission (-150 to 0km/s) 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.
© ESO 2019
galaxies: high-redshift - galaxies: ISM - gravitational lensing: strong - submillimeter: galaxies - radio lines: ISM - ISM: molecules
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<Available at CDS (J/A+A/624/A138): list.dat fits/*>
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