ALMA and PKS 1830-211: the Molecular Absorption and the Background Blazar

The line of sight to the lensed blazar PKS1830-211 intercepts the disk of a foreground spiral galaxy at z=0.89, yielding absorption detected in 40+ molecular species. These molecules can be used as cosmological probes at a look-back time of more than half the present age of the Universe. We can determine their excitation and measure the temperature of the cosmic microwave background, compare their kinematics and set constraints on the variations of the fundamental constants, measure the isotopic ratios from different isotopologues and investigate the elemental enrichment from stellar processes, and, of course, investigate the chemistry in the disk of the absorber. Besides, we obtained ALMA data observed serendipitously at the time of a strong gamma-ray flare of the background blazar, allowing us to investigate its submm activity and the submm to gamma-ray connection. Last we present the first ALMA polarimetry results, with the highest Faraday rotation ever measured, revealing a strong magnetic field at the base of the jet in PKS 1830-211. In short, one target, but many and diverse science results !