282 citations · 611 across the 7 of their papers we have counts for
6 papers
Chandra Observations of low velocity dispersion groups
Stephen F. Helsdon, Trevor J. Ponman, J. S. Mulchaey
Deviations of galaxy groups from cluster scaling relations can be understood in terms of an excess of entropy in groups. The main effect of this excess is to reduce the density and…
The morphology-density relation in X-ray bright galaxy groups
Stephen F. Helsdon, Trevor J. Ponman
We have examined the morphological make-up of X-ray bright groups. The brighter galaxies in these groups exhibit clear morphology-density and morphology-radius relations. The group…
X-ray bright groups and their galaxies
Stephen F. Helsdon, Trevor J. Ponman
Combining X-ray data from the ROSAT PSPC and optical data drawn from the literature, we examine in detail the relationship between the X-ray and optical properties of X-ray bright…
X-ray luminosities of galaxies in groups
Stephen F. Helsdon, Trevor J. Ponman, Ewan O'Sullivan +1
We have derived the X-ray luminosities of a sample of galaxies in groups, making careful allowance for contaminating intragroup emission. The L_X:L_B and L_X:L_{FIR} relations of s…
Are X-ray properties of loose groups different from those of compact groups?
S. F. Helsdon, T. J. Ponman
We compare the X-ray properties of loose and compact galaxy groups, using a combined sample of 42 groups. We find that we are unable to separate loose and compact groups on the lum…
The intragroup medium in loose groups of galaxies
S. F. Helsdon, T. J. Ponman
We have used the ROSAT PSPC to study the properties of a sample of 24 X-ray bright galaxy groups, representing the largest sample examined in detail to date. Hot plasma models are…