Chemical complexity in feedback from supernova remnants: First detection of PO+ in IC443 and W44
Year: 2026
Type: article
Abstract: Supernova remnant (SNR) shocks may play a role in shaping the initial physical and chemical properties of star formation in galaxies. By releasing refractory elements into the gas phase, they could potentially inject material of pre-biotic significance into molecular clouds, which could later be inherited by planetary systems. Therefore, such shocks could indeed be relevant for the emergence of life as we know it. In this work, we investigate the presence of phosphorus-bearing (P-bearing) species in molecular clouds impacted by SNR shocks. Phosphorus is a crucial biological element, but its presence and main reservoir in molecular clouds remain highly elusive. We present high-sensitivity 3 mm single-pointing observations obtained with the 30 m antenna at the Instituto de Radioastronomia Millímetrica, towards the interaction sites between the SNRs W44 and IC443 and their associated molecular clouds. Focussing on the detection of PO+(2-1) and PN(2-1), we derived the molecular column densities and abundances in local thermodynamic equilibrium (LTE). Here, we discuss the implication of this assumption and we investigate the correlation between P-bearing species and the shock tracer silicon monoxide (SiO). We detected, for the first time, PO+$ emission towards SNRs, with abundances of ̧hi(PO^+)∼ 8times10^-12-5times10^-11. On the other hand, no significant PN emission was detected. In particular, PO^+ towards both SNRs is associated with strong SiO emission, showing similar line widths, but systematic velocity offsets, suggesting that PO^+ preferentially traces the most compressed and possibly more strongly ionised layers of the shock. Moreover, by comparing the derived abundance with those reported in literature towards other star-forming regions, we suggest that the PO$^+ abundance mainly depends on a combination of shock strength and shocked medium density. Our results indicate that phosphorus chemistry in SNR-driven shocks is shifted towards an ion-dominated regime, likely driven by enhanced cosmic-ray ionisation rates. In this scenario, neutral species such as PN are efficiently destroyed, while ion-molecule reactions favour the production of PO+. These findings suggest that SNR-driven shocks might play a role in processing phosphorus-bearing material and shaping gas-phase phosphorus chemistry in molecular clouds, with potential implications for the chemical inventory of star-forming environments.
Source: Astronomy and Astrophysics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W7216509313