Andrew Fabian
Institute of Astronomy, University of Cambridge (Cambridge, Royaume-Uni)
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris
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| « Hidden cooling flows in clusters and groups of galaxies » |
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Andrew Fabian |
| Half of all clusters of galaxies have a cool core in which the gas temperature drops inward and the density rises as expected from a cooling flow. Over 20 years ago, simple analyses of high resolution X-ray spectra showed little evidence for the cooling flow continuing below 1 keV at the rates inferred from higher temperatures. We have now re-examined the RGS spectra of over 20 clusters and groups and 4 early-type galaxies and find that an intrinsically-absorbed (Hidden) Cooling Flow model allows for significant continuous mass cooling rates to 0.1 keV and below at the level of 15-50% of the expected rates from above 1 keV. The rates range from 1-20 Msun/yr in groups to 15-100 in regular clusters. Several highly luminous clusters have mass cooling rates of 1000 Msun/yr or more. Where available, the Far Infrared flux is compatible with that expected from X-ray absorption. Larger scale AGN feedback can account for 50-85% of the reduction in mass cooling rates but the remainder is significant. We discuss these results and outline the possible fate of the cooled gas, including Very Cold Gas Clouds, Low- Mass Star Formation, outward dragging by rising bubbles and non-luminous swallowing by the central black hole. |
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vendredi 26 mai 2023 - 11:00 Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |