PKS 1830-211 OH and HI spectra

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 6100L_{sun}_. This is the most luminous known 1720MHz maser line.

It is also among the highest luminosities for the OH-main lines megamasers. 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 20yrs ago, and find no variation, in spite of the high signal-to-noise ratios.

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. The resulting absorption lines depend mainly on the background continuum, and the radial distribution of the gas surface density, for each atomic /molecular species.We show that it is possible to reproduce the observations assuming a realistic spiral galaxy disk, without invoking any central gas outflows.

There are, however, distinct and faint high-velocity features in the ALMA millimeter absorption spectra, that most likely originate from high-velocity clouds or tidal features. These clouds may contribute to broaden the Hi and OH spectra.