  We investigate the regularity of galaxy cluster gas density profiles and the
link to the relation between core-excised luminosity, LXc, and mass from the Yx
proxy, MYx, for 93 SZE-selected objects. The sample spans masses M500=[0.5 -
20] x 10e14 Msun, and lies at redshifts 0.05<z<1.13. Using XMM-Newton
observations, we derive an average ICM density profile for the SZE-selected
systems and determine its scaling with mass and redshift. This average profile
evolves slightly stronger than self-similar (a_z = 2.09+/-0.02), and has
significant dependence on mass (a_M = 0.22 +/- 0.01). Deviations from the
average scaling with radius indicate different evolution for the core regions
and the bulk. We measure the radial variation of the intrinsic scatter, finding
a slight evolution with redshift. The average profile of the SZE-selected
systems describes that of X-ray-selected systems at low redshift. The scaled
core properties are positively skewed at later times, suggesting an increased
incidence of centrally peaked objects at lower redshifts. The relation between
LXc and MYx has an intrinsic scatter of 13%. Using simulations, we investigate
the impact of selection effects, intrinsic scatter, and covariance on this
relation. The slope is insensitive to selection and intrinsic scatter between
quantities; however, the scatter is very dependent on the covariance between
LXc and Yx. Accounting for our use of the Yx proxy to determine the mass, we
estimate an upper limit to the intrinsic scatter with respect to the true mass
of 22%. We probe the connection between the scatter in density profiles and
that in the LXc-M relation. Our results suggest that the ICM bulk evolves
approximately self-similarly, with the core regions evolving separately;
indicate a variation of the gas content with mass; and show that LXc has a
tight relation to the underlying mass.
