On Extragalactic Phosphorus Nitride, PN

D. Haasler, V. M. Rivilla, S. Martín, J. Holdship, S. Viti, N. Harada, J. Mangum, K. Sakamoto, S. Muller, K. Tanaka, Y. Yoshimura, K. Nakanishi, L. Colzi, L. Hunt, K. L. Emig, R. Aladro, P. Humire, C. Henkel, and P. van der Werf
reported on the
First Extragalactic Detection of a Phosphorus-bearing Molecule with ALCHEMI: Phosphorus Nitride (PN)
Astron. Astrophys. 659, (2022) Art. No. A158.

The J = 2 – 1 and J = 3 – 2 transitions of PN near 93.980 and 140.968 GHz, respectively, were observed with ALMA in the course of a very extensive molecular line survey (84.2 to 373.2 GHz) of the central molecular zone (CMZ) of the near-by star-burst galaxy NGC 253. Both transitions were detected toward the source GMC 6 with good and fairly good signal-to-noise ratios (S/N), respectively. The J = 2 – 1 transition was also detected with reasonable S/N toward the source GMC 4. The two transitions detected toward GMC 6 constrain the excitation temperature to 4.4 ± 1.3 K.

Other phosphorus-bearing molecules were searched for, but not detected. The PO/PN ratio was found to be < 1.3 for GMC 6, still compatible with PO/PN > 1 in Galactic sources. The PH3/PN ratio was found to be < 2.7 toward the same position.


Contributor(s): H. S. P. Müller; 04, 2022