科研之友
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摘要
Studying the flow of baryons into and out of galaxies is an important part of understanding the evolution of galaxies over time. We present a detailed case study of the environment around an intervening Ly alpha absorption line system at z(abs) = 0.633, seen towards the quasar J0423-0130 (z(QSO) = 0.915). We detect with ALMA the (CO)-C-12(2-1), (CO)-C-12(3-2), and 1.2 mm continuum emission from a galaxy at the redshift of the Ly alpha absorber at a projected distance of 135 kpc. From the ALMA detections, we infer interstellar medium conditions similar to those in low-redshift luminous infrared galaxies. Director's Discretionary Time (DDT) Multi-Unit Spectroscopic Explorer (MUSE) integral field unit observations reveal the optical counterpart of the (CO)-C-12 emission line source and three additional emission line galaxies at the absorber redshift, which together form a galaxy group. The (CO)-C-12 emission line detections originate from the most massive galaxy in this group. While we cannot exclude that we miss a fainter host, we reach a dust-uncorrected star formation rate (SFR) limit of >0.3 M-circle dot yr(-1) within 100 kpc from the sightline to the background quasar. We measure the dust-corrected SFR (ranging from 3 to 50 M-circle dot yr(-1)), the morpho-kinematics and the metallicities of the four group galaxies to understand the relation between the group and the neutral gas probed in absorption. We find that the Ly alpha absorber traces either an outflow from the most massive galaxy or intragroup gas. This case study illustrates the power of combining ALMA and MUSE to obtain a census of the cool baryons in a bounded structure at intermediate redshift.
- 出版日期2018-3
