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arXiv · 2509.16572

Atomic and molecular gas in the Milky Way. I. Structure decomposition

Xin Liu·Fujun Du
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Abstract

We present GDCluster, a fully automated algorithm for decomposing spectral-line datacube of interstellar gas into coherent structures. Assuming a multi-Gaussian nature of observed spectra, GDCluster employs and augments the derivative spectroscopy technique for precise parameter estimation, incorporates spatial-continuity constraints during spectral fitting, and extends these constraints to spatial clustering. This approach effectively resolves velocity blending structures in PPV space-particularly critical for ubiquitous HI spectra where emissions from multiple phases are severely blended. Applied to the all-sky HI4PI data, a 10 degree times 10 degree CRAFTS survey region, and a 45 degree times 10 degree MWISP survey region, GDCluster extracts 45,299, 2247, and 47,119 structures in HI and CO (1-0), respectively. Comparative analyses demonstrate GDCluster's superiority over DBSCAN in separating overlapping spectra with complex velocity components.

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Xin Liu, Fujun Du. 2025-09-20. Atomic and molecular gas in the Milky Way. I. Structure decomposition. https://arxiv.org/abs/2509.16572

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