Cosmo-tomography toward PKS1830−211: Variability of the quasar and of its foreground molecular absorption monitored with ALMA

Context. Time variability of astronomical sources provides crude information on their typical size and the implied physical mechanisms. PKS 1830−211 is a remarkable radio-bright lensed quasar with foreground molecular absorber in lens galaxy at z = 0.89. Small-scale morphological changes core–jet structure – which magnified by lensing result varying illumination screen, turn causes variations absorption profile. Aims. We aim to study time system (the two main images corresponding sightlines absorber) order obtain constraints both activity small-scale structures interstellar medium absorber. Methods. used ALMA monitor submillimeter continuum emission 1830−211, together spectra H 2 O CH molecules, 17 visits spread over six months 2016. Complementing this, we available data investigate period 2012−2022. Results. From data, followed evolution flux density, flux-density ratio, spectral index, differential polarization between quasar; all quantities show significant related intrinsic quasar. propose simple parametric model core plus ballistic plasmon account for evolution, from constrain delay 25 ± 3 days images. The lines reveal A principal component analysis highlights apparent wavy variations, possibly linked helical jet precession deep averaged towards southwest image, detect rare isotopolog 13 estimate an abundance ratio 12 CH/ ∼ 150. also measure oxygen isotopic ratios, 16 O/ 18 65.3 0.7 11.5 0.5 0.89 Finally, find continuous shallow trough water spanning velocity interval nearly 500 km s −1 . This broad could be signature extra-planar component. Conclusions. All together, formed its lens–absorber acts as powerful gravitational microscope, providing us possibility dissect ISM background