  Using X-ray temperature and surface brightness profiles of the hot
intracluster medium derived from ASCA and ROSAT observations we place
constraints on the dark matter and baryon fraction distributions in the poor
clusters Abell 1060 and AWM 7. Although their total mass distributions are
similar, AWM 7 has twice the baryon fraction of Abell 1060 in the best-fit
models. The functional form of the dark matter distribution is ill-determined,
however mass models where the baryon fractions in Abell 1060 and AWM 7
significantly overlap are excluded. Such variations in baryon fraction are not
predicted by standard models and imply that some mechanism in addition to
gravity plays a major role in organizing matter on cluster scales.
