The GUAPOS Project: G31.41+0.31 Unbiased ALMA Spectral Observational Survey. IV. Phosphorus-bearing Molecules And Their Relation With Shock Tracers

By Keith Cowing
Status Report
November 24, 2023
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The GUAPOS Project: G31.41+0.31 Unbiased ALMA Spectral Observational Survey. IV. Phosphorus-bearing Molecules And Their Relation With Shock Tracers
Emission of SO, SiS, and SO2 integrated in velocity. Upper panels: velocity-integrated emission of, from left to right, SO N = 3 − 2, N = 2 − 1(2), N = 2 − 1(3), and N = 4 − 4 (see Table 1 for the spectral parameters). The integration velocity range is 85.7–105.8 km s−1 in all images to match the velocity interval where the PN emission is detected. The black contours start from the 3σ rms level of the integrated maps, which is, from left to right: 4.8 × 10−2 Jy beam−1 km s−1 ; 2.5 × 10−2 Jy beam−1 km s−1 ; 3.6 × 10−2 Jy beam−1 km s−1 ; 2.7 × 10−2 Jy beam−1 km s−1 , and the step is of 10σ rms. The white contour corresponds to the PN integrated emission, and the numbered regions “1” and “2” are those defined in Fig. 1. The synthesised beam is illustrated in the lower-left corner. To the right of the quantum numbers, we indicate the Eup of the transition. Lower panels: same as the upper panels for the SiS J = 5 − 4 and J = 6 − 5 lines, and the SO2 JKa,Kb = 31,3 − 20,2 and JKa,Kb = 101,9 − 100,10 lines. The 3σ rms level is: 2.9 × 10−2 Jy beam−1 km s−1 for SiS J = 5 − 4; 2.3 × 10−2 Jy beam−1 km s−1 for SiS J = 6 − 5; 2.95 × 10−3 Jy beam−1 km s−1 for SO2 JKa,Kb = 31,3 − 30,2; 1 × 10−2 Jy beam−1 km s−1 for SO2 JKa,Kb = 101,9 − 100,10. — astro-ph.GA

The astrochemistry of the important biogenic element phosphorus (P) is still poorly understood, but observational evidence indicates that P-bearing molecules are likely associated with shocks.

We study P-bearing molecules, as well as some shock tracers, towards one of the chemically richest hot molecular core, G31.41+0.31, in the framework of the project “G31.41+0.31 Unbiased ALMA sPectral Observational Survey” (GUAPOS), observed with the Atacama Large Millimeter Array (ALMA). We have observed the molecules PN, PO, SO, SO2, SiO, and SiS, through their rotational lines in the spectral range 84.05-115.91 GHz, covered by the GUAPOS project. PN is clearly detected while PO is tentatively detected.

The PN emission arises from two regions southwest of the hot core peak, “1” and “2”, and is undetected or tentatively detected towards the hot core peak. the PN and SiO lines are very similar both in spatial emission morphology and spectral shape. Region “1” is in part overlapping with the hot core and it is warmer than region “2”, which is well separated from the hot core and located along the outflows identified in previous studies.

The column density ratio SiO/PN remains constant in regions “1” and “2”, while SO/PN, SiS/PN, and SO2/PN decrease by about an order of magnitude from region “1” to region “2”, indicating that SiO and PN have a common origin even in regions with different physical conditions. Our study firmly confirms previous observational evidence that PN emission is tightly associated with SiO and it is likely a product of shock-chemistry, as the lack of a clear detection of PN towards the hot-core allows to rule out relevant formation pathways in hot gas. We propose the PN emitting region “2” as a new astrophysical laboratory for shock-chemistry studies

F. Fontani (1,2,3), C. Mininni (4), M.T. Beltrán (1), V.M. Rivilla (5), L. Colzi (5), I. Jiménez-Serra (5), Á. López-Gallifa (5), Á. Sánchez-Monge (6,7), S. Viti (8) ((1) INAF-Osservatorio Astrofisico di Arcetri, (2) Max-Planck-Institute for Extraterrestrial Physics (MPE), (3) LERMA, Observatoire de Paris, (4) INAF-Istituto di Astrofisica e Planetologia Spaziali, (5) Centro de Astrobiología (INTA-CSIC), (6) Institut de Ciéncies de l Espai (ICE, CSIC), (7) Institut de Estudis Espacials de Catalunya (IEEC), (8) Leiden Observatory)

Comments: 15 pages, 11 figures, accepted for publication in A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2311.13367 [astro-ph.GA] (or arXiv:2311.13367v1 [astro-ph.GA] for this version)
Submission history
From: Francesco Fontani
[v1] Wed, 22 Nov 2023 13:06:47 UTC (1,370 KB)
Astrobiology, Astrochemistry

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻