Chemical enrichment of the Intracluster Medium
- Author(s)
- Verena Baumgartner, Dieter Breitschwerdt
- Abstract
X-ray observations (e.g. Fukazawa et al. 1998) show that the Intracluster Medium (ICM) contains metals with abundances ~ 0.2 - 0.3 Z ⊙. Since heavy elements are produced mainly in stars of cluster galaxies, they must have been transported into the intracluster space. We investigate the efficiency of galactic winds, expelling metals from the galaxies and hence being one of the main contributors for ICM enrichment. The most powerful outflows are provided by starburst-type galaxies where the global star formation rate is typically enhanced by a factor of 10 or more. Type II SN-Explosions originating from OB stars in associations create a large cavity filled with hot rarefied gas containing the processed material. In our model we describe SN-Explosions as a continuous process applying the thin-shell approximation for the expansion of the superbubble (Kompaneets 1960) in an exponentially stratified ambient medium. After having reached a few scale heights the accelerating outer shell breaks up due to Rayleigh-Taylor instabilities allowing hot and metal enriched gas to blow out of the disk and into the ICM (MacLow et al. 1989). It is possible for the mass-loaded wind to escape from the potential well of the galaxy if the energy input is sufficiently high i.e. the velocity of the flow exceeds the escape velocity of the galaxy. As time proceeds a halo of metal enriched wind gas will surround the galaxy (as a "relic wind") and will therefore be coupled to the Hubble flow. Since the star formation rate had a peak at redshift z ~ 2, and was still higher up to z ~ 5 than today, the metals stripped from these winds during cluster formation should be taken into account with respect to the enrichment of the ICM. Deriving the supernova rate from a cluster IMF we show solutions for bubbles breaking out of the disk and feeding the halo. These serve as an input into a numerical wind simulation (Breitschwerdt et al. 1991), from which we deduce mass loss and hence chemical enrichment rates. Comparisons are made between the various processes supplying metal enriched material. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Organisation(s)
- Department of Astrophysics
- Journal
- Astronomische Nachrichten
- Volume
- 326
- Pages
- 485
- ISSN
- 0004-6337
- DOI
- https://doi.org/10.1002/asna.200585001
- Publication date
- 2005
- Austrian Fields of Science 2012
- 103003 Astronomy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/5807e4b8-d75d-4639-a370-cf6ebe5c9b7a