Directly imaging the cooling flow in the Phoenix cluster.

Area of Science:

• Astrophysics
• Galaxy Evolution
• Cosmic Plasma Physics

Background:

• Galaxy clusters contain hot intracluster medium (ICM) that should cool rapidly.
• The "cooling flow problem" describes the discrepancy between expected gas cooling and observed low star formation rates.
• Previous theories suggested black hole jets prevent ICM cooling, but direct evidence across all gas phases was lacking.

Purpose of the Study:

• To map gas phases in a galaxy cluster core at unprecedented scale and resolution.
• To investigate the cooling flow problem by observing the Phoenix cluster.
• To understand the role of black hole feedback in regulating ICM cooling and star formation.

Main Methods:

• Utilized the James Webb Space Telescope (JWST) for observations.
• Mapped the [Ne VI] λ 7.652-μm emission line to probe gas at 10^5.5 Kelvin.
• Analyzed gas phases across a range of temperatures (10^5 K to 10^6 K) in the cluster core.

Main Results:

• Detected extended [Ne VI] emission cospatial with the coolest ICM and star-forming regions.
• Evidence suggests a recent, rapid cooling episode in the Phoenix cluster.
• Estimated a short-lived spike in the cooling rate, between 5,000-23,000 solar masses per year.

Conclusions:

• The study provides the first large-scale map of gas across multiple temperature phases in a cluster core.
• Observations indicate that black hole feedback can both regulate and promote gas cooling.
• The findings challenge the notion that black hole jets solely prevent cooling, suggesting a more complex interplay.