APEX telescope observations of new molecular ions

TL;DR

This study reports the detection of key interstellar hydrides SH+ and OH+ using the APEX telescope, revealing their abundance in diffuse clouds and providing a systematic survey of these molecules across the Galaxy.

Contribution

First systematic survey of SH+ and OH+ hydrides in diffuse clouds and star-forming regions using APEX telescope observations.

Findings

Detected widespread absorption of hydrides in diffuse clouds.

Hydrides are abundant components of interstellar medium.

Surveyed multiple regions in the Galaxy for hydride presence.

Abstract

Hydrides are key ingredients of interstellar chemistry since they are the initial products of chemical networks that lead to the formation of more complex molecules. The fundamental rotational transitions of light hydrides fall into the submillimeter wavelength range. Using the APEX telescope, we observed the long sought hydrides SH+ and OH+ in absorption against the strong continuum source Sagittarius B2(M). Both, absorption from Galactic center gas as well as from diffuse clouds in intervening spiral arms over a large velocity range is observed. The detected absorption of a continuous velocity range on the line of sight shows these hydrides to be an abundant component of diffuse clouds. In addition, we used the strongest submillimeter dust continuum sources in the inner Galaxy to serve as background candles for a systematic census of these hydrides in diffuse clouds and massive star forming regions of our Galaxy and initial results of this survey are presented.