文章基本信息

标题：OH+ and H2O+ absorption toward PKS 1830–211
本地全文：下载
作者：S. Muller ; S. Muller ; H. S. P. Müller 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2016
卷号：595
页码：1-10
DOI：10.1051/0004-6361/201629073
语种：English
出版社：EDP Sciences
摘要：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.
关键词：quasars: absorption lines;quasars: individual: PKS 1830;211;galaxies: abundances;radio lines: galaxies;galaxies: ISM;ISM: molecules