PKS1830-211: OH and HI at z=0.89 and the first MeerKAT UHF spectrum

Abstract

The Large Survey Project (LSP) "MeerKAT Absorption Line Survey" (MALS) is a blind HI 21-cm and OH 18-cm absorption line survey in the L- and UHF-bands, with the primary goal to better determine the occurrence of atomic and molecular gas in the circum-galactic and inter-galactic medium, and its redshift evolution. Here we present the first results using the UHF-band, obtained towards the strongly lensed radio source PKS1830, detecting absorption in the lens galaxy. With merely 90min of data acquired on-source for science verification and processed using the Automated Radio Telescope Imaging Pipeline (ARTIP), we detect in absorption the known HI 21-cm and OH 18-cm main lines at z=0.89 at an unprecedented signal-to-noise ratio (4000 in the continuum, with 6km/s channels). For the first time we report the detection at z=0.89 of OH satellite lines, so far not detected at z $>$ 0.25. We decompose the OH lines into a thermal and a stimulated contribution, where the 1612 and 1720MHz lines are conjugate. The total OH 1720MHz emission line luminosity is 6100Lsun. This is the most luminous known 1720MHz maser line. The absorption components of the different images of the background source sample different light paths in the lensing galaxy, and their weights in the total absorption spectrum are expected to vary in time, on daily and monthly time scales. We compare our normalized spectra with those obtained more than 20 yrs ago, and find no variation. We interpret the absorption spectra with the help of a lens galaxy model, derived from an N-body hydro-dynamical simulation, with a morphology similar to its optical HST image. It is possible to reproduce the observations without invoking any central gas outflows. There are, however, distinct and faint high-velocity features, most likely high-velocity clouds. These clouds may contribute to broaden the HI and OH spectra.

arXiv comment13 pages, 11 figures, accepted in Astronomy and Astrophysics

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• A study of submillimeter methanol absorption toward PKS1830-211: Excitation, invariance of the proton-electron mass ratio, and systematics
• Evolution of cold gas at 2<z<5: a blind search for HI and OH absorption lines towards mid-infrared color selected radio-loud AGNs
• LADUMA: Discovery of a luminous OH megamaser at $z>0.5$
• MALS SALT-NOT survey of MIR-selected powerful radio-bright AGN at 0<z<3.5
• Detections of 21-cm absorption with a blind FAST survey at z $⩽$ 0.09
• Cosmo-tomography toward PKS1830-211: Variability of the quasar and of its foreground molecular absorption monitored with ALMA
• The MeerKAT Absorption Line Survey: Homogeneous continuum catalogues towards a measurement of the cosmic radio dipole
• Discovery of Hydrogen Radio Recombination Lines at z=0.89 towards PKS 1830-211
• PKS1413+135: OH and HI at z = 0.247 with MeerKAT
• A sub-ppm upper limit on the cosmological variations of the fine structure constant alpha
• New constraints on the values of the fundamental constants at a look-back time of 7.3 Gyr
• Quasars behind the disk of M31 galaxy
• An improved time delay from VLA and ATCA monitoring of the gravitational lens system PKS 1830-211