Hostname: page-component-cd9895bd7-8ctnn Total loading time: 0 Render date: 2024-12-12T08:30:51.707Z Has data issue: false hasContentIssue false
  • English
  • Français

Measures of Galactic and Intergalactic Mass in Clusters

Published online by Cambridge University Press:  25 May 2016

D. Windridge ,
S. Phillipps  and
M. Birkinshaw
D. Windridge
Affiliation:
Astrophysics Group, University of Bristol
S. Phillipps
Affiliation:
Astrophysics Group, University of Bristol
M. Birkinshaw
Affiliation:
Astrophysics Group, University of Bristol

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

If a galaxy cluster's X-ray gas distribution follows an isothermal polytropic β model, we may write the electron radial density distribution as; ne = ne0(1 + r2/rc2)–3/2β, rc being the core radius and ne0 the central electron density. This may be related to both an X-ray surface brightness distribution and a Sunyaev-Zel'dovich effect distribution (Sarazin 1986). Fitting to observational data then enables us to constrain the value of β. The normalisation value, ne0, to obtain a total mass estimate is calculated via the relationship between the X-ray and S-Z distribution normalisation constants, and the gas temperature and spectral emissivity parameters from fits to the X-ray spectrum. We are then in a position to evaluate ne(r) and its integral; the total electron gas mass. If we can further assume that there exists a simple ratio between the electron and proton number densities within the gas, we may straightforwardly posit a value for the total gas mass. An additional method of determining the polytropic gas index exists, with optical constraints on the galactic velocity dispersion, through the relation; β = μmHσz2/kBTe. Studies at optical, as well as X-ray and radio wavelengths are thus useful as a corroborative measure in determining the total gas mass.

Type
Part 5. Extra-Galactic Astronomy
Information
Symposium - International Astronomical Union , Volume 179: New Horizons from Multi-Wavelength Sky Surveys , 1998 , pp. 266 - 267
Copyright
Copyright © Kluwer 1998 

References

Birkinshaw, M. & Hughes, J. P., 1994, Astrophys. J. 420, 33.Google Scholar
Driver, S. P. et al., 1994, Mon. Not. R. astron. Soc. 266, 155.Google Scholar
Irwin, M. & Hatzidimitriou, D., 1995, Mon. Not. R. astron. Soc. 277, 1354.Google Scholar
Longmore, A. J. et al., 1982, Mon. Not. R. astron. Soc. 200, 325.CrossRefGoogle Scholar
Persic, M. & Salucci, P., 1992, Mon. Not. R. astron. Soc. 258, 14P.Google Scholar
Sarazin, C. L., 1986, Rev. Mod. Phys. 58, 1.Google Scholar
Schechter, P. L., 1976, Astrophys. J. 203, 297.CrossRefGoogle Scholar