Simulating the Cooling Flow of Cool-Core Clusters
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Transcript of Simulating the Cooling Flow of Cool-Core Clusters
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Simulating the Cooling Flow of Cool-Core Clusters
Yuan LiAdvisor: Greg Bryan
Department of Astronomy, Columbia University
July 2011
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The Cooling Flow Problem
• In Cool-Core Clusters: tcool << Hubble Time• Steady state => Cooling flow• 100s Msun /yr >> SFR => Heating sources: AGN
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• How cold gas cools out of the flow: local or global? • The amount of cold gas produced• The rate of gas accretion on to a central SMBH• The lack of cool gas observed in X-rays• The impact of other processes (thermal
conduction, Type Ia SN heating, etc) on the cooling instability
• Will focus on heating in later work
Key Questions:
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Simulation Setup• Enzo, an Adaptive Mesh
Refinement (AMR) code: Mpc to pc scale (smallest cell: 2pc)
• 3D, spherical symmetric + rotation • An Isolated Cluster at z = 1• Comoving box size = 16 Mpc/h• NFW Dark Matter + BCG + SMBH +
gas• Initial gas density and
temperature: observations of Perseus Cluster
• Initial pressure: HSE• Initial velocity: Gaussian random
velocity + rotation• No feedback (yet)
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Results: Density Temperature and Pressure
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Compressional Heating / Cooling Rotational Support
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Results: Time-scales
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16.6 kpc
Projection-z
t=296 Myr
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330 pc
Projection-z
t=296 Myr
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330 pc
Projection-x
t=296 Myr
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Results: The Amount of Cool GasCompared to Observations
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Results: Estimated AGN Feedback
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Results: Impact of Resolution
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Conclusion• A global cooling catastrophe occurs first at a transition radius
of about 50 pc from the SMBH• The temperature profile remains remarkably flat as the cluster
core cools• There is a distinct lack of gas below a few keV• Local thermal instabilities do not grow outside the transition
radius• Thermal conduction and Type Ia SN heating are not important• The final result is sensitive to the presence of the BCG and the
resolution of the simulation• Next step: including feedback
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Results: Gas Inflow Velocity
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Classic Cooling Flow