Phosphorus-bearing molecules in the Galactic Center

V M Rivilla, I Jiménez-Serra, S Zeng, S Martín, J Martín-Pintado, J Armijos-Abendaño, S Viti, R Aladro, D Riquelme, M Requena-Torres, D Quénard, F Fontani, M T Beltrán. 2018. Phosphorus-bearing molecules in the Galactic Center. Monthly Notices of the Royal Astronomical Society 475, 1, DOI: 10.1093/mnrasl/slx208

Phosphorus (P) is one of the essential elements for life due to its central role in biochemical processes. Recent searches have shown that P-bearing molecules (in particular PN and PO) are present in star-forming regions, although their formation routes remain poorly understood. In this letter, we report observations of PN and PO towards seven molecular clouds located in the Galactic Center, which are characterized by different types of chemistry. PN is detected in five out of seven sources, whose chemistry is thought to be shock-dominated. The two sources with PN non-detections correspond to clouds exposed to intense UV/X-rays/cosmic ray (CR) radiation. PO is detected only towards the cloud G+0.693-0.03, with a PO/PN abundance ratio of similar to 1.5. We conclude that P-bearing molecules likely form in shocked gas as a result of dust grain sputtering, while are destroyed by intense UV/X-ray/CR radiation.

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