OH+ and H2O+ absorption toward PKS 1830-211
Journal article, 2016
We report the detection of OH+ and H2O+ in the z = 0.89 absorber toward the lensed quasar PKS 1830-211. The abundance ratio of OH+ and H2O+ is used to quantify the molecular hydrogen fraction (fH2) and the cosmic-ray ionization rate of atomic hydrogen (ζH) along two lines of sight, located at 2 kpc and 4 kpc to either side of the absorber's center. The molecular fraction decreases outward, from 0.04 to 0.02, comparable to values measured in the Milky Way at similar galactocentric radii. For ζH , we find values of 2 × 10-14 s-1 and 3 × 10-15 s-1, respectively, which are slightly higher than in the Milky Way at comparable galactocentric radii, possibly due to a higher average star formation activity in the z = 0.89 absorber. The ALMA observations of OH+, H2O+, and other hydrides toward PKS 1830-211reveal the multi-phase composition of the absorbing gas. Taking the column density ratios along the southwest and northeast lines of sight as a proxy of molecular fraction, we classify the species ArH+, OH+, H2Cl+, H2O+, CH, and HF as tracing gases increasingly more molecular. Incidentally, our data allow us to improve the accuracy of H2O+ rest frequencies and thus refine the spectroscopic parameters.
quasar absorption lines
quasars
interstellar molecules
galaxies: abundances
Author
Sebastien Muller
Chalmers, Earth and Space Sciences, Onsala Space Observatory
H. S. P. Müller
University of Cologne
John H Black
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
A. Beelen
Institut d'Astrophysique Spatiale
F. Combes
Centre national de la recherche scientifique (CNRS)
S.J. Curran
Victoria University of Wellington
M. Gerin
Ecole Normale Superieure (ENS)
M. Guélin
Ecole Normale Superieure (ENS)
Institut de Radioastronomie Millimétrique (IRAM)
C. Henkel
Max Planck Society
King Abdulaziz University
S. Martín
European Southern Observatory Santiago
Susanne Aalto
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
E. Falgarone
Ecole Normale Superieure (ENS)
K. M. Menten
Max Planck Society
P. Schilke
University of Cologne
Tommy Wiklind
Catholic University of America
M. A. Zwaan
European Southern Observatory (ESO)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 595 A128(1-10) A128Subject Categories
Astronomy, Astrophysics and Cosmology
Roots
Basic sciences
Infrastructure
Onsala Space Observatory
DOI
10.1051/0004-6361/201629073