other query modes : |
Identifier query |
Coordinate query |
Criteria query |
Reference query |
Basic query |
Script submission |
TAP |
Output options |
Help |
2004MNRAS.350.1511O - Mon. Not. R. Astron. Soc., 350, 1511-1535 (2004/June-1)
The GEMS project: X-ray analysis and statistical properties of the group sample.
OSMOND J.P.F. and PONMAN T.J.
Abstract (from CDS):
The steepening of the LX-TXrelation in the group regime reported previously is not seen in our sample, which fits well on to the cluster trend, albeit with large non-statistical scatter. A number of biases affect the fitting of regression lines under these circumstances, and until the impact of these has been thoroughly investigated it seems best to regard the slope of the group LX-TXrelation as being poorly determined. A significant problem in comparing the properties of groups and clusters is the derivation of system radii, to allow different systems to be compared within regions having the same overdensity. We find evidence that group velocity dispersion (σv) provides a very unreliable measure of system mass (and hence radius), with a number of groups having remarkably low values of σv, given that they appear from their X-ray properties to be collapsed systems. We confirm that the surface brightness profiles of groups are significantly flatter than those of clusters - the maximum value of the βfitparameter for our sample is 0.58, lower than the typical value of 0.67 seen in clusters - however, we find no significant tendency within our sample for cooler groups to show flatter profiles. This result is inconsistent with simple universal pre-heating models. The morphology of the galaxies in the GEMS groups is correlated to their X-ray properties in a number of ways: we confirm the very strong relationship between X-ray emission and a dominant early-type central galaxy, which has been noted since the early X-ray studies of groups, and also find that spiral fraction is correlated with the temperature of the hot gas and hence the depth of the gravitational potential. A class of spiral-rich groups with little or no X-ray emission probably corresponds to groups that have not yet fully collapsed.
Abstract Copyright: 2004 RAS
Journal keyword(s): galaxies: clusters: general - galaxies: evolution - galaxies: formation - galaxies: general - intergalactic medium - X-rays: galaxies: clusters
Simbad objects: 111
To bookmark this query, right click on this link: simbad:2004MNRAS.350.1511O and select 'bookmark this link' or equivalent in the popup menu
© Université de Strasbourg/CNRS
• Contact