On the Abiotic Origin of Dimethyl Sulfide: Discovery of DMS in the Interstellar Medium

Following the discovery of dimethyl sulfide (CH₃SCH₃, DMS) signatures in comet 67P/Churyumov-Gerasimenko, we report the first detection of this organosulfur species in the interstellar medium, during the exploration of an ultradeep molecular line survey performed toward the Galactic Center molecular cloud G+0.693-0.027 with the Yebes 40m and IRAM 30m telescopes.

We derive a molecular column density of N = (2.6 ± 0.3)×10¹³ cm⁻², yielding a fractional abundance relative to H₂ of ∼1.9×10⁻¹⁰. This implies that DMS is a factor of ∼1.6 times less abundant than its structural isomer CH₃CH₂SH and ∼30 times less abundant than its O-analogue dimethyl ether (CH₃OCH₃) toward this cloud, in excellent agreement with previous results on various O/S pairs.

Furthermore, we find a remarkable resemblance between the relative abundance of DMS/CH₃OH in G+0.693-0.027 (∼1.7×10⁻³) and in the comet (∼1.3×10⁻³). Although the chemistry of DMS beyond Earth is yet to be fully disclosed, this discovery provides conclusive observational evidence on its efficient abiotic production in the interstellar medium, casting doubts about using DMS as a reliable biomarker in exoplanet science.

Miguel Sanz-Novo, Víctor M. Rivilla, Christian P. Endres, Valerio Lattanzi, Izaskun
Jiménez-Serra, Laura Colzi, Shaoshan Zeng, Andrés Megías, Álvaro López-Gallifa, Antonio Martínez-Henares, David San Andrés, Belén Tercero, Pablo de Vicente, Sergio Martín, Miguel A. Requena-Torres, Paola Caselli, Jesús Martín-Pintado

Comments: Accepted in ApJL
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2501.08892 [astro-ph.GA](or arXiv:2501.08892v2 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2501.08892
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Related DOI:
https://doi.org/10.3847/2041-8213/adafa7
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Submission history
From: Miguel Sanz-Novo
[v1] Wed, 15 Jan 2025 16:03:04 UTC (3,820 KB)
[v2] Mon, 3 Feb 2025 07:20:27 UTC (3,820 KB)
https://arxiv.org/abs/2501.08892

Astrobiology, Astrochemistry,