# Odin observations of ammonia in the Sgr A +50 km/s Cloud and Circumnuclear Disk

## TL;DR

This study uses Odin satellite observations to detect ammonia in the Galactic Centre's +50 km/s Cloud and Circumnuclear Disk, revealing emission and absorption features that inform about shock processes and gas dynamics.

## Contribution

It provides new observational data on ammonia in the Galactic Centre, highlighting the presence of NH3 emission and absorption in specific regions and suggesting shock-related formation mechanisms.

## Key findings

- NH3 emission detected in +50 km/s Cloud and CND
- NH3 absorption observed in spiral arm features
- Large velocity width indicates shock-related gas processes

## Abstract

Context. The Odin satellite is now into its sixteenth year of operation, much surpassing its design life of two years. One of the sources which Odin has observed in great detail is the Sgr A Complex in the centre of the Milky Way. Aims. To study the presence of NH3 in the Galactic Centre and spiral arms. Methods. Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the Sgr A +50 km/s Cloud and Circumnuclear Disk (CND). Results. Significant NH3 emission has been observed in both the +50 km/s Cloud and the CND. Clear NH3 absorption has also been detected in many of the spiral arm features along the line of sight from the Sun to the core of our Galaxy. Conclusions. The very large velocity width (80 km/s) of the NH3 emission associated with the shock region in the southwestern part of the CND may suggest a formation/desorption scenario similar to that of gas-phase H2O in shocks/outflows.