| Issue |
A&A
Volume 472, Number 3, September IV 2007
|
|
|---|---|---|
| Page(s) | 727 - 737 | |
| Section | Cosmology (including clusters of galaxies) | |
| DOI | https://doi.org/10.1051/0004-6361:20077466 | |
| Published online | 02 July 2007 | |
High redshift X-ray galaxy clusters*
I. The impact of point sources on the cluster properties
1
Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: m.branchesi@ira.inaf.it
2
INAF – Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy e-mail: [gioia;rfanti;cfanti]@ira.inaf.it
Received:
13
March
2007
Accepted:
17
June
2007
Context.The current generation of X-ray observatories like Chandra allows studies with very fine spatial details. It is now possible to resolve X-ray point sources projected into the cluster diffuse emission and exclude them from the analysis to estimate the “correct” X-ray observables.
Aims.We wish to verify the incidence of point sources on the cluster thermal emission and to evaluate the impact of their non-thermal emission on the determination of cluster properties.
Methods.To these ends we use a sample of 18 high-z (0.25 < z < 1.01) clusters from the Chandra archive and subtract the non-thermal emission of the point sources from the extended thermal emission due to the cluster itself. We perform a detailed analysis of the cluster properties and compare the changes observed in the X-ray observables, like temperature and luminosity or their inter-relation, when one keeps the point sources in the analysis.
Results.The point sources projected into the cluster extended emission
affect the estimates of cluster temperature or luminosity considerably
(up to 13% and 17% respectively). These percentages become even
larger for clusters with 
0.7 where temperature and luminosity
increase up to 24% and 22%, respectively.
Conclusions.The conclusions are that point sources should be removed to correctly estimate the cluster properties. However the inclusion of the point sources does not impact significantly the slope and normalization of the Lbol–T relationship since for each cluster the correction to be applied to T and Lbol produces a moderate shift in the Lbol–T plane almost parallel to the best-fit of the “correct” Lbol–T relation.
Key words: galaxies: clusters: general / galaxies: high-redshift / cosmology: observations / galaxies: intergalactic medium / X-rays: galaxies: clusters
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.