Identification of molecular clouds in emission maps: a comparison between methods in the 13CO/C18O (J = 3–2) Heterodyne Inner Milky Way Plane Survey

Raffaele Rani*, Toby J.T. Moore, David J. Eden, Andrew J. Rigby, Ana Duarte-Cabral, Yueh Ning Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The growing range of automated algorithms for the identification of molecular clouds and clumps in large observational data sets has prompted the need for the direct comparison of these procedures. However, these methods are complex and testing for biases is often problematic: only a few of them have been applied to the same data set or calibrated against a common standard. We compare the FELLWALKER method, a widely used watershed algorithm, to the more recent Spectral Clustering for Interstellar Molecular Emission Segmentation (SCIMES). SCIMES overcomes sensitivity and resolution biases that plague many friends-of-friends algorithms by recasting cloud segmentation as a clustering problem. Considering the 13CO/C18O (J = 3–2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) and the CO High-Resolution Survey (COHRS), we investigate how these two different approaches influence the final cloud decomposition. Although the two methods produce largely similar statistical results over the CHIMPS dataset, FW appears prone to oversegmentation, especially in crowded fields where gas envelopes around dense cores are identified as adjacent, distinct objects. FW catalogue also includes a number of fragmented clouds that appear as different objects in a line-of-sight projection. In addition, cross-correlating the physical properties of individual sources between catalogues is complicated by different definitions, numerical implementations, and design choices within each method, which make it very difficult to establish a one-to-one correspondence between the sources.

Original languageEnglish
Pages (from-to)1832-1852
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume523
Issue number2
DOIs
Publication statusPublished - 2023 Aug 1

Keywords

  • ISM: clouds
  • methods: data analysis
  • molecular data
  • submillimetre: ISM
  • surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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