Chlorine-bearing molecules in molecular absorbers at intermediate redshifts
Journal article, 2019

We use observations of chlorine-bearing species in molecular absorbers at intermediate redshifts to investigate chemical properties and Cl-35/Cl-37 isotopic ratios in the absorbing sightlines. Chloronium (H2Cl+) is detected along three independent lines of sight in the z = 0.89 and z = 0.68 molecular absorbers located in front of the lensed quasars PKS 1830-211 and B 0218+357, respectively. Hydrogen chloride (HCl) was observed only toward PKS 1830-211, and is found to behave differently from H2Cl+. It is detected in one line of sight with an abundance ratio [H2Cl+]/[HCl] similar to 1, but remains undetected in the other, more diffuse, line of sight, with a ratio [H2Cl+] / [HCl] > 17. The absorption profiles of these two chlorine-bearing species are compared to other species and discussed in terms of the physical properties of the absorbing gas. Our findings are consistent with the picture emerging from chemical models where different species trace gas with different molecular hydrogen fraction. The Cl-35/Cl-37 isotopic ratios are measured in the different lines of sight and are discussed in terms of stellar nucleosynthesis.

quasars: individual: PKS 1830-211

galaxies: ISM

galaxies: abundances

quasars: individual: B 0218+357

radio lines: galaxies

quasars: absorption lines


S. H. J. Wallstrom

Academia Sinica

KU Leuven

Sebastien Muller

Chalmers, Space, Earth and Environment, Onsala Space Observatory, Onsala Space Observatory, Observation Support

Evelyne Roueff

Pierre and Marie Curie University (UPMC)

R. Le Gal

Harvard-Smithsonian Center for Astrophysics

John H Black

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

M. Gerin

Pierre and Marie Curie University (UPMC)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 629 A128

Subject Categories

Astronomy, Astrophysics and Cosmology


Theoretical Chemistry


Onsala Space Observatory



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