ALMA observations of a metal-rich damped Ly α absorber at z = 2.5832: evidence for strong galactic winds in a galaxy group

Abstract

We report on the results of a search for CO(3-2) emission from the galaxy counterpart of a high-metallicity Damped Lyα Absorber (DLA) at z = 2.5832 towards the quasar Q0918+1636. We do not detect CO emission from the previously identified DLA galaxy counterpart. The limit we infer on M gas /M is in the low end of the range found for DLA galaxies, but is still consistent with what is found for other star-forming galaxies at similar redshifts. Instead we detect CO(3-2) emission from another intensely star-forming galaxy at an impact parameter of 117 kpc from the line-of-sight to the quasar and 131 km s −1 redshifted relative to the velocity centroid of the DLA in the quasar spectrum. In the velocity profile of the low-and high-ionisation absorption lines of the DLA there is an absorption component consistent with the redshift of this CO-emitting galaxy. It is plausible that this component is physically associated with a strong outflow in the plane of the sky from the CO-emitting galaxy. If true, this would be further evidence, in addition to what is already known from studies of Lyman-break galaxies, that galactic outflows can be traced beyond 100 kpc from star-forming galaxies. The case of this z = 2.583 structure is an illustration of this in a group environment.

Quasar Sightline and Galaxy Evolution (QSAGE) survey – I. The galaxy environment of O vi absorbers up to z = 1.4 around PKS 0232−04

“…voids, filaments, groups, and clusters) with respect to observations of the CGM (e.g. Penton, Stocke & Shull 2002;Aracil et al 2006;Tejos et al 2012Tejos et al , 2016Stocke et al 2014;Burchett et al 2016Burchett et al , 2018Fumagalli et al 2016Fumagalli et al , 2017bBielby et al 2017a;Péroux et al 2017;Fynbo et al 2018;Pessa et al 2018). Such studies are adding important context to for interpreting CGM observations, but are again primarily limited to z 0.5 or z > 2.…”

A Long Stream of Metal-Poor Cool Gas around a Massive Starburst Galaxy at z = 2.67

“…Interestingly, the DLA galaxies previously identified in the optical/near-IR are not detected in CO and vice versa (Kanekar et al 2020), indicating that observations at different wavelength are complementary to one another and that H I-absorption-selection tags gas-rich galaxies of all types. Some DLAs also have multiple emission counterparts that are consistent with the absorption redshifts, suggesting a group/cluster environment (e.g., Fynbo et al 2018).…”

The nature of H{\sc i}-absorption-selected galaxies at $z \approx 4$

“…Recently, significant progress has been made in identifying the galaxies associated with high-z DLAs, using mm-wave studies with the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA searches for redshifted [CII] 158µm and CO emission associated with high-metallicity DLAs have resulted in the identification of more than ten HI-selected galaxies, out to z ≈ 4.5 (e.g., Neeleman et al 2017Neeleman et al , 2018Neeleman et al , 2019Fynbo et al 2018;Kanekar et al 2020). The ALMA DLA galaxies have been found to lie mostly at large impact parameters to the QSO sightline, b 15 kpc, very different from the HI-selected galaxies identified in optical imaging (e.g., Neeleman et al 2019;Kanekar et al 2020).…”

“…Molecular gas and dust in high-z HI-selected galaxies JVLA or ALMA searches for CO emission have now been carried out in more than 30 absorption-selected galaxies, at z ≈ 0.1 − 4.8, with more than 15 detections of CO emission (e.g. Neeleman et al 2016Neeleman et al , 2018Neeleman et al , 2020Møller et al 2018;Kanekar et al 2018Kanekar et al , 2020Fynbo et al 2018;Klitsch et al 2019;Péroux et al 2019). At z < 1 and z ≈ 4, most of the HI-selected galaxies had earlier been identified via their optical or [CII] 158µm emission, while, at z ≈ 2, the CO searches were themselves used to identify the HI-selected galaxy.…”