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We present the results of a search for unidentified emission lines in deepSuzaku X-ray spectra for the central regions of the four X-ray brightest galaxyclusters: Perseus, Coma, Virgo and Ophiuchus. We employ an optimized energyrange for our analysis (3.2-5.3 keV) that is relatively free of instrumentalfeatures, and a baseline plasma emission model that incorporates the abundancesof elements with the strongest expected emission lines at these energies (S,Ar, Ca) as free parameters. For the Perseus Cluster core, employing thisbaseline model, we find evidence for an additional emission feature at anenergy $3.51^{+0.02}_{-0.01}$ keV with a flux of ~$2.87\times10^{-7}$ph/s/cm^2/arcmin^2. At slightly larger radii, we detect an emission line at3.59+/-0.02 keV with a flux of ~$4.8\times10^{-8}$ ph/s/cm^2/arcmin^2. Theenergies and fluxes of these features are broadly consistent with previousclaims, although the radial variation of the line strength appears in tensionwith standard dark matter (DM) model predictions. Assuming a decaying DM originfor the Perseus emission features allows us to predict the energies and linefluxes for the other clusters in our sample. Critically, we do not detect anemission feature at the predicted energy and line flux in the Coma, Virgo andOphiuchus clusters. The formal 99.5 per cent upper limits on the strengths ofan emission line in each cluster are below the decaying DM model predictions,scaling from the Perseus Cluster center, apparently ruling the model out. Inthe light of these results, we search for other explanations for the ~3.55 keVemission feature in Perseus. Our results suggest that systematic effectsassociated with modeling the complex spectra for the Perseus Cluster core,details of the assumed ionization balance, and errors in the predictedemissivities of the spectral lines may in part be responsible for the ~3.5 keVfeature.

A Suzaku Search for Dark Matter Emission Lines in the X-ray Brightest Galaxy Clusters