Maser Activity of Organic Molecules toward Sgr B2(N)

By Keith Cowing
Status Report
April 24, 2024
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Maser Activity of Organic Molecules toward Sgr B2(N)
Infrared sources towards Sgr B2(N) reported by the GLIMPSE IRC 4 Band at 8.0µm (Left) and the 2MSAA Ks Band at 2.2µm (Right). The 84 GHz CH3OH maser emission at 58.5 km s−1 is shown with contours, as in Figure 2(r). — astro-ph.GA

At centimeter wavelengths, single-dish observations have suggested that the Sagittarius (Sgr) B2 molecular cloud at the Galactic Center hosts weak maser emission from several organic molecules, including CH2NH, HNCNH, and HCOOCH3.

However, the lack of spatial distribution information of these new maser species has prevented us from assessing the excitation conditions of the maser emission as well as their pumping mechanisms. Here, we present a mapping study toward Sgr B2 North (N) to locate the region where the complex maser emission originates.

We report the first detection of the Class I methanol (CH3OH) maser at 84 GHz and the first interferometric map of the methanimine (CH2NH) maser at 5.29 GHz toward this region. In addition, we present a tool for modeling and fitting the unsaturated molecular maser signals with non-LTE radiative transfer models and Bayesian analysis using the Markov-Chain Monte Carlo approach. These enable us to quantitatively assess the observed spectral profiles.

The results suggest a two-chain-clump model for explaining the intense CH3OH Class I maser emission toward a region with low continuum background radiation. By comparing the spatial origin and extent of maser emission from several molecular species, we find that the 5.29 GHz CH2NH maser has a close spatial relationship with the 84 GHz CH3OH Class I masers. This relationship serves as observational evidence to suggest a similar collisional pumping mechanism for these maser transitions.

Ci Xue, Anthony Remijan, Alexandre Faure, Emmanuel Momjian, Todd R. Hunter, Ryan A. Loomis, Eric Herbst, Brett McGuire

Comments: 17 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2404.12622 [astro-ph.GA] (or arXiv:2404.12622v1 [astro-ph.GA] for this version)
Submission history
From: Ci Xue
[v1] Fri, 19 Apr 2024 04:41:26 UTC (4,410 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) 🖖🏻