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- Cooling_flow abstract "A cooling flow occurs according to the theory that the intracluster medium (ICM) in the centres of galaxy clusters should be rapidly cooling at the rate of tens to thousands of solar masses per year. This should happen as the ICM (a plasma) is quickly losing its energy by the emission of X-rays. The X-ray brightness of the ICM is proportional to the square of its density, which rises steeply towards the centres of many clusters. Also the temperature falls to typically a third or a half of the temperature in the outskirts of the cluster. The typical timescale for the ICM to cool is relatively short, less than a billion years. As material in the centre of the cluster cools out, the pressure of the overlying ICM should cause more material to flow inwards (the cooling flow).In a steady state, the rate of mass deposition, i.e. the rate at which the plasma cools, is given by where L is the bolometric (i.e. over the entire spectrum) luminosity of the cooling region, T is its temperature, k is the Boltzmann constant and μm is the mean molecular mass.It is currently thought that the very large amounts of expected cooling are in reality much smaller, as there is little evidence for cool X-ray emitting gas in many of these systems. This is the cooling flow problem. Theories for why there is little evidence of cooling include Heating by the central Active galactic nucleus (AGN) in clusters, possibly via sound waves (seen in the Perseus and Virgo clusters) Thermal conduction of heat from the outer parts of clusters Cosmic ray heating Hiding cool gas by absorbing material Mixing of cool gas with hotter materialHeating by AGN is the most popular explanation, as they emit a lot of energy over their lifetimes, and some of the alternatives listed have theoretical problems.".
- Cooling_flow wikiPageID "12770444".
- Cooling_flow wikiPageRevisionID "544912178".
- Cooling_flow hasPhotoCollection Cooling_flow.
- Cooling_flow subject Category:Extragalactic_astronomy.
- Cooling_flow subject Category:Galaxy_clusters.
- Cooling_flow subject Category:Space_plasmas.
- Cooling_flow type Abstraction100002137.
- Cooling_flow type Agglomeration107959269.
- Cooling_flow type BodySubstance105263850.
- Cooling_flow type Bunch107959943.
- Cooling_flow type Collection107951464.
- Cooling_flow type ExtracellularFluid105398023.
- Cooling_flow type GalaxyClusters.
- Cooling_flow type Group100031264.
- Cooling_flow type LiquidBodySubstance105397468.
- Cooling_flow type Matter100020827.
- Cooling_flow type Part113809207.
- Cooling_flow type PhysicalEntity100001930.
- Cooling_flow type Plasma105403427.
- Cooling_flow type Relation100031921.
- Cooling_flow type SpacePlasmas.
- Cooling_flow type Substance100019613.
- Cooling_flow comment "A cooling flow occurs according to the theory that the intracluster medium (ICM) in the centres of galaxy clusters should be rapidly cooling at the rate of tens to thousands of solar masses per year. This should happen as the ICM (a plasma) is quickly losing its energy by the emission of X-rays. The X-ray brightness of the ICM is proportional to the square of its density, which rises steeply towards the centres of many clusters.".
- Cooling_flow label "Cooling Flow".
- Cooling_flow label "Cooling flow".
- Cooling_flow label "Courant de refroidissement".
- Cooling_flow sameAs Cooling_Flow.
- Cooling_flow sameAs Courant_de_refroidissement.
- Cooling_flow sameAs m.02x4553.
- Cooling_flow sameAs Q1129714.
- Cooling_flow sameAs Q1129714.
- Cooling_flow sameAs Cooling_flow.
- Cooling_flow wasDerivedFrom Cooling_flow?oldid=544912178.
- Cooling_flow isPrimaryTopicOf Cooling_flow.