Astrochemistry

Detections Of Interstellar 2-cyanopyrene And 4-cyanopyrene In TMC-1

By Keith Cowing
Status Report
astro-ph.GA
October 4, 2024
Filed under , , , , , , , , ,
Detections Of Interstellar 2-cyanopyrene And 4-cyanopyrene In TMC-1
Velocity-stacked spectra and matched filter responses of 2- and 4-cyanopyrene. The stacked GOTHAM observations (black) are overlaid with the simulated stacked spectrum of 2- and 4-cyanopyrene (blue and pink, respectively), each consisting of the 150 brightest SNR lines (left panels). Marginalized posterior parameters were used in both simulations, as reported in Supplementary Table A3. The corresponding impulse response for the matched filtering analysis is shown, yielding a significance of 8.0 σ and 12.9 σ for the 2- and 4-cyanopyrene detections, respectively (right panels). The small features in the stacked simulated spectrum (pink) in the bottom left panel result from the densely populated 4-cyanopyrene lines (see Fig. A3) that add up in the stack. — astro-ph.GA

Polycyclic aromatic hydrocarbons (PAHs) are among the most ubiquitous compounds in the universe, accounting for up to ~25% of all interstellar carbon. Since most unsubstituted PAHs do not possess permanent dipole moments, they are invisible to radio astronomy.

Constraining their abundances relies on the detection of polar chemical proxies, such as aromatic nitriles. We report the detection of 2- and 4-cyanopyrene, isomers of the recently detected 1-cyanopyrene. We find that these isomers are present in an abundance ratio of ~2:1:2, which mirrors the number of equivalent sites available for CN addition.

We conclude that there is evidence that the cyanopyrene isomers formed by direct CN addition to pyrene under kinetic control in hydrogen-rich gas at 10 K and discuss constraints on the H/CN ratio for PAHs in TMC-1.

Gabi Wenzel, Thomas H. Speak, P. Bryan Changala, Reace H. J. Willis, Andrew M. Burkhardt, Shuo Zhang, Edwin A. Bergin, Alex N. Byrne, Steven B. Charnley, Zachary T. P. Fried, Harshal Gupta, Eric Herbst, Martin S. Holdren, Andrew Lipnicky, Ryan A. Loomis, Christopher N. Shingledecker, Ci Xue, Anthony J. Remijan, Alison E. Wendlandt, Michael C. McCarthy, Ilsa R. Cooke, Brett A. McGuire

Comments: Accepted in Nature Astronomy; version is prior to editorial revisions
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2410.00670 [astro-ph.GA] (or arXiv:2410.00670v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2410.00670
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Submission history
From: Brett McGuire
[v1] Tue, 1 Oct 2024 13:28:42 UTC (5,999 KB)
https://arxiv.org/abs/2410.00670

Astrobiology, Astrochemistry,

Keith Cowing

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) 🖖🏻

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