Molecular Emission from a Galaxy Associated with a z sim 2.2 Damped Ly$ Absorber

TY - JOUR

T1 - Molecular Emission from a Galaxy Associated with a z sim 2.2 Damped Ly$ Absorber

AU - Neeleman, M.

AU - Kanekar, N.

AU - Prochaska, J.~X.

AU - Christensen, L.

AU - Dessauges-Zavadsky, M.

AU - Fynbo, J.~P.~U.

AU - Møller, P.

AU - Zwaan, M.~A.

PY - 2018/3/20

Y1 - 2018/3/20

N2 - Using the Atacama Large Millimeter/submillimeter Array, we have detected CO(3-2) line and far-infrared continuum emission from a galaxy associated with a high-metallicity ([M/H] = -0.27) damped Lyα absorber (DLA) at z DLA = 2.19289. The galaxy is located 3.″5 away from the quasar sightline, corresponding to a large impact parameter of 30 kpc at the DLA redshift. We use archival Very Large Telescope-SINFONI data to detect Hα emission from the associated galaxy, and find that the object is dusty, with a dust-corrected star formation rate of Mo yr-1. The galaxy's molecular mass is large, Mmol = (1.4 ± 0.2) × 1011 × (α CO/4.3) × (0.57/r 31) M o, supporting the hypothesis that high-metallicity DLAs arise predominantly near massive galaxies. The excellent agreement in redshift between the CO(3-2) line emission and low-ion metal absorption (∼40 km s-1) disfavors scenarios whereby the gas probed by the DLA shows bulk motion around the galaxy. We use Giant Metrewave Radio Telescope H i 21 cm absorption spectroscopy to find that the H i along the DLA sightline must be warm, with a stringent lower limit on the spin temperature of T s > 1895 × (f/0.93) K. The detection of C i absorption in the DLA, however, also indicates the presence of cold neutral gas. To reconcile these results requires that the cold components in the DLA contribute little to the H i column density, yet contain roughly 50% of the metals of the absorber, underlining the complex multi-phase nature of the gas surrounding high-z galaxies.

AB - Using the Atacama Large Millimeter/submillimeter Array, we have detected CO(3-2) line and far-infrared continuum emission from a galaxy associated with a high-metallicity ([M/H] = -0.27) damped Lyα absorber (DLA) at z DLA = 2.19289. The galaxy is located 3.″5 away from the quasar sightline, corresponding to a large impact parameter of 30 kpc at the DLA redshift. We use archival Very Large Telescope-SINFONI data to detect Hα emission from the associated galaxy, and find that the object is dusty, with a dust-corrected star formation rate of Mo yr-1. The galaxy's molecular mass is large, Mmol = (1.4 ± 0.2) × 1011 × (α CO/4.3) × (0.57/r 31) M o, supporting the hypothesis that high-metallicity DLAs arise predominantly near massive galaxies. The excellent agreement in redshift between the CO(3-2) line emission and low-ion metal absorption (∼40 km s-1) disfavors scenarios whereby the gas probed by the DLA shows bulk motion around the galaxy. We use Giant Metrewave Radio Telescope H i 21 cm absorption spectroscopy to find that the H i along the DLA sightline must be warm, with a stringent lower limit on the spin temperature of T s > 1895 × (f/0.93) K. The detection of C i absorption in the DLA, however, also indicates the presence of cold neutral gas. To reconcile these results requires that the cold components in the DLA contribute little to the H i column density, yet contain roughly 50% of the metals of the absorber, underlining the complex multi-phase nature of the gas surrounding high-z galaxies.

KW - galaxies: high-redshift, galaxies: ISM, galaxies: kinematics and dynamics, quasars: absorption lines, submillimeter: galaxies

U2 - 10.3847/2041-8213/aab5b1

DO - 10.3847/2041-8213/aab5b1

M3 - Journal article

SN - 2041-8205

VL - 856

SP - L12-L18

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

IS - 1

ER -