The recent weak-lensing measurement of the dark matter mass of the high-redshift galaxy cluster XMMUJ2235.3-2557 of $(8.5\pm 1.7)\times {10}^{14}{M}_{\odot }$ at $z=1.4$, indicates that, if the cluster is assumed to be the result of the collapse of dark matter in a primordial Gaussian field in the standard lambda cold dark matter model, then its abundance should be $<2\times {10}^{-3}$ clusters in the observed area. Here we investigate how to boost the probability of XMMUJ2235.3-2557, in particular, resorting to deviations from Gaussian initial conditions. We show that this abundance can be boosted by factors $>3–10$ if the non-Gaussianity parameter $f_{\mathrm{NL}}^{\mathrm{local}}$ is in the range 150–200. This value is comparable to the limit for $f_{\mathrm{NL}}$ obtained by current constraints from the cosmic microwave background. We conclude that mass determination of high-redshift, massive clusters can offer a complementary probe of primordial non-Gaussianity.

• Received 2 September 2009

DOI:https://doi.org/10.1103/PhysRevD.80.127302