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Correlation of cold molecular gas with Hα and X-ray filaments

Determine whether the cold (<100 K) molecular gas phase in filamentary structures of cool-core clusters exhibits a quantitative correlation with the Hα and soft X-ray emission, using sufficiently sensitive ALMA observations to detect diffuse CO emission in faint filaments.

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Background

While this work establishes a tight correlation between Hα and X-ray surface brightness in filaments, the cold molecular phase carries most of the filament mass. Preliminary studies report spatial and kinematic alignment between CO and the brightest Hα emission, but current ALMA sensitivity limits hinder detections of diffuse cold gas in faint Hα filaments.

Confirming or refuting a correlation between cold molecular gas properties and warm/hot emission would clarify the multiphase structure and energetics of filaments and their role in AGN feeding.

References

In addition to the Hα and X-ray correlation discussed in this paper, it is currently unknown whether there is any correlation with the cold (<100 K) gas phase, which carries the bulk of the mass of the filaments. We leave the correlation with the cold molecular gas properties using ALMA (Atacama Large Millimeter Array) observations for a future study.

— H$α$-X-ray Surface Brightness Correlation for Filaments in Cooling Flow Clusters (2501.01902 - Olivares et al., 3 Jan 2025) in Main text, concluding discussion before Methods