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Astrochemistry overview and challenges: Machine Learning Approach

Hakima MOKRANE

Astrochemistry is the field studying chemical processes in astronomical environments. It is rapidly evolving and explores the issue of the formation of molecules of increasing complexity in space and particular physical conditions that deviate significantly from those frequently encountered in chemistry laboratories.
The presence of this molecular diversity constitutes a firm evidence that efficient formation processes in the interstellar medium. This talk aims to introduce a new methodology and new approach for studying astrochemistry and present ideas that are explored by astrochemists to investigate the chemistry taking place in various astronomical environments.
The more ambitious question of the molecular complexity is addressed, the issue of molecular complexity constitutes one of the main modern scientific questions addressed by astrochemistry.
More than 200 different species detected up today in the interstellar and circumstellar media have also been identified in icy environments. The formation of water molecules from the reaction between O3 and D-atoms is studied experimentally for the first time. Ozone is deposited on non-porous amorphous solid water ice, and D-atoms are then sent onto the sample held at 10 K. HDO molecules are detected during the desorption of the whole substrate where isotope mixing takes place, indicating that water synthesis has occurred. The efficiency of water formation via hydrogenation of ozone is of the same order of magnitude as that found for reactions involving O-atoms or O2 molecules and exhibits no apparent activation barrier. These experiments validate the assumption made by models using ozone as one of the precursors of water formation via solid-state chemistry on interstellar dust grains. The fact that, for most of the species observed so far in the ISM, the most abundant isomer of a given generic chemical formula is the most stable one (MEP) suffers very few exceptions. Two couples of isomers, CH3COOH/HCOOCH3 and CH3CH2OH/CH3OCH3 whose formation is thought to occur on the icy mantles of interstellar grains. Here I applied machine learning and AI to build and improve molecular reactions and I will introduce a new methodology in astrochemistry.