Simple models of cooling flows
A semi-analytic model of cluster cooling flows is presented. The model assumes that episodic nuclear activity followed by radiative cooling without mass-dropout cycles the cluster gas between a relatively homogeneous, nearly isothermal post-outburst state and a cuspy configuration in which a cooling...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2002
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| _version_ | 1826288664668274688 |
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| author | Kaiser, C Binney, J |
| author_facet | Kaiser, C Binney, J |
| author_sort | Kaiser, C |
| collection | OXFORD |
| description | A semi-analytic model of cluster cooling flows is presented. The model assumes that episodic nuclear activity followed by radiative cooling without mass-dropout cycles the cluster gas between a relatively homogeneous, nearly isothermal post-outburst state and a cuspy configuration in which a cooling catastrophe initiates the next nuclear outburst. Fitting the model to Chandra data for the Hydra cluster, a lower limit of $284\Myr$ until the next outburst of Hydra A is derived. Density, temperature and emission-measure profiles at several times prior to the cooling catastrophe are presented. It proves possible to fit the mass $M(\sigma)$ with entropy index $P\rho^{-\gamma}$ less than $\sigma$ to a simple power-law form, which is almost invariant as the cluster cools. We show that radiative cooling automatically establishes this power-law form if the entropy index was constant throughout the cluster gas at some early epoch or after an AGN activity cycle. To high precision, the central value of $\sigma$ decreases linearly in time. The fraction of clusters in a magnitude-limited sample that have gas cooler than $T$ is calculated, and is shown to be small for $T=2\keV$. Similarly, only 1 percent of clusters in such a sample contain gas with $P\rho^{-\gamma} < 2\keV\cm^2$. Entropy production in shocks is shown to be small. The entropy that is radiated from the cluster can be replaced if a few percent of the cluster gas passes through bubbles heated during an outburst of the AGN. |
| first_indexed | 2024-03-07T02:17:08Z |
| format | Journal article |
| id | oxford-uuid:a2a6654c-1471-4b36-8e37-b0b84724fa0b |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T02:17:08Z |
| publishDate | 2002 |
| record_format | dspace |
| spelling | oxford-uuid:a2a6654c-1471-4b36-8e37-b0b84724fa0b2022-03-27T02:21:25ZSimple models of cooling flowsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:a2a6654c-1471-4b36-8e37-b0b84724fa0bEnglishSymplectic Elements at Oxford2002Kaiser, CBinney, JA semi-analytic model of cluster cooling flows is presented. The model assumes that episodic nuclear activity followed by radiative cooling without mass-dropout cycles the cluster gas between a relatively homogeneous, nearly isothermal post-outburst state and a cuspy configuration in which a cooling catastrophe initiates the next nuclear outburst. Fitting the model to Chandra data for the Hydra cluster, a lower limit of $284\Myr$ until the next outburst of Hydra A is derived. Density, temperature and emission-measure profiles at several times prior to the cooling catastrophe are presented. It proves possible to fit the mass $M(\sigma)$ with entropy index $P\rho^{-\gamma}$ less than $\sigma$ to a simple power-law form, which is almost invariant as the cluster cools. We show that radiative cooling automatically establishes this power-law form if the entropy index was constant throughout the cluster gas at some early epoch or after an AGN activity cycle. To high precision, the central value of $\sigma$ decreases linearly in time. The fraction of clusters in a magnitude-limited sample that have gas cooler than $T$ is calculated, and is shown to be small for $T=2\keV$. Similarly, only 1 percent of clusters in such a sample contain gas with $P\rho^{-\gamma} < 2\keV\cm^2$. Entropy production in shocks is shown to be small. The entropy that is radiated from the cluster can be replaced if a few percent of the cluster gas passes through bubbles heated during an outburst of the AGN. |
| spellingShingle | Kaiser, C Binney, J Simple models of cooling flows |
| title | Simple models of cooling flows |
| title_full | Simple models of cooling flows |
| title_fullStr | Simple models of cooling flows |
| title_full_unstemmed | Simple models of cooling flows |
| title_short | Simple models of cooling flows |
| title_sort | simple models of cooling flows |
| work_keys_str_mv | AT kaiserc simplemodelsofcoolingflows AT binneyj simplemodelsofcoolingflows |