Maser Activity of Organic Molecules toward Sgr B2(N)
Name
Xue_2024_ApJ_967_164.pdf
Description
Published version
Size
3.3 MB
Format
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Checksum (MD5)
ec34e361e04218412ba37c360322892e
Author(s)
Xue, Ci
Remijan, Anthony
Faure, Alexandre
Momjian, Emmanuel
Hunter, Todd R
Loomis, Ryan A
Herbst, Eric
McGuire, Brett
Date Issued
May 30, 2024
Journal
The Astrophysical Journal
Publisher
American Astronomical Society
Citation
Ci Xue et al 2024 ApJ 967 164
Version
Final published version
Abstract
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 on 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.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.3847/1538-4357/ad4094
