The search for complex molecules in the ISM: a complete 3 mm line survey of Sgr B2-N and -M

TL;DR

This study presents a comprehensive 3 mm line survey of the Sgr B2-N and -M molecular cloud cores, revealing a rich molecular diversity and providing detailed spectral data crucial for understanding complex molecule formation in space.

Contribution

It offers the first complete 3 mm molecular line survey of Sgr B2-N and -M, identifying numerous molecular species, isotopologues, and vibrational states, and advances spectral analysis methods in astrochemistry.

Findings

Detected about 100 features/GHz in Sgr B2(N)

Identified 51 molecular species in Sgr B2(N)

Uncovered 41 molecular species in Sgr B2(M)

Abstract

Famous for the extraordinary richness of its molecular content, the Sgr B2 molecular cloud complex is the prime target in the long-standing search for ever more complex species. We have completed a molecular line survey of the hot dense cores Sgr B2(N) and Sgr B2(M) in the 3 mm wavelength range with the IRAM 30 m telescope. We performed the analysis of this huge data set by modeling the whole spectrum at once in the LTE approximation. Ongoing analyses yield an average line density of about 100 features/GHz above 3 sigma for Sgr B2(N), emitted and/or absorbed by a total of 51 molecular species. We find lines from 60 rare isotopologues and from 41 vibrationally excited states in addition to the main species, vibrational ground state lines. For Sgr B2(M), we find about 25 features/GHz above 3 sigma, from 41 molecular species plus 50 isotopologues and 20 vibrationally excited states. Thanks to the constant updates to the Cologne Database for Molecular Spectroscopy, we are working our way through the assignment of the unidentified features, currently 40% and 50% above 3 sigma for Sgr B2(N) and Sgr B2(M), respectively.