Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ===== Argonium, ArH+, in Extragalactic Sources ===== H. S. P. Müller, S. Muller, P. Schilke, E. A. Bergin, J. H. Black, M. Gérin, D. C. Lis, D. A. Neufeld, and S. Suri,\\ reported on the\\ **[[https://doi.org/10.1051/0004-6361/201527254|Detection of Extragalactic Argonium, ArH<sup>+</sup>, toward PKS 1830–211]]**\\ //Astron. Astrophys.// **582**, (2015) Art. No. L4.\\ The ground state rotational transitions of <sup>36</sup>ArH<sup>+</sup> and <sup>38</sup>ArH<sup>+</sup> were observed in absorption in the //z// = 0.89 foreground galaxy toward the quasar PKS 1830–211. The Atacama Large Millimeter Array (ALMA) was used in its Early Science Cycle 2 phase. The transitions were redshifted from about 617 GHz to about 327 GHz. The interstellar abundance of <sup>40</sup>Ar is almost negligible, and <sup>40</sup>ArH<sup>+</sup> was accordingly not detected. The <sup>36</sup>Ar/<sup>38</sup>Ar isotopic ratios were 3.46 ± 0.16 and 4.53 ± 0.33 toward the stronger SW and the weaker NE image, respectively. The values differ from 5.50 ± 0.01 in the Solar neighborhood, suggesting that high-mass supernovae played a greater role in creating elements heavier than helium (metals for astronomers) in the early Universe compared to today, as one would expect; the look-back time at //z// = 0.89 is about 7.5 billion years.\\ \\ We know from [[molecules:ism:arh-plus|Galactic observations]] that argonium is an excellent tracer of the almost purely atomic and very diffuse interstellar medium.\\ \\ A. M. Jacob, K. M. Menten, F. Wyrowski, B. Winkel, D. A. Neufeld and B. S. Koribalski<br> reported on\\ **[[https://doi.org/10.1051/0004-6361/202142544|ArH<sup>+</sup> and H<sub>2</sub>O<sup>+</sup> Absorption towards Luminous Galaxies]]**\\ //Astron. Astrophys.// **659**, (2022) Art. No. 152.\\ The //J// = 1 − 0 transition of <sup>36</sup>ArH<sup>+</sup> was detected with the APEX 12 m dish toward the nearby galaxies NGC 253, NGC 4945, and Arp 220. The molecular fraction of the gas traced by ArH<sup>+</sup> was estimated to be ~10<sup>−3</sup> and that it resides in gas volumes with low electon densities.\\ \\ ---- Contributor(s): H. S. P. Müller; 10, 2015; 04, 2022 ---- molecules/extragalactic/arh-plus_extragalactic.txt Last modified: 2022/04/04 12:53by mueller