Direct probes of dark matter in the cluster 1ES0657-556 through microwave observations

Aims. The cluster 1ES0657-556 is an ideal astrophysical laboratory to study the distribution and the nature of Dark Matter because this last component is spatially separated from the intracluster gas. We show that microwave observations can provide crucial probes of Dark Matter in this system. Methods. We calculate the expected SZ effect from Dark Matter annihilation in the main mass concentrations of the cluster 1ES0657-556, and we estimate the sources of contamination, confusion and bias to asses its significance. Results. We find that SZ observations at ν ≈ 223 GHz can resolve both spatially and spectrally the SZDM signal and isolate it from the other SZ signals, and mainly from the thermal SZ effect which is null at ν ∼ 220-223 GHz for the case of 1ES0657-556. We conclude that SZ observations with ≲arcmin resolution and ≲μK sensitivity of 1ES0657-556 are crucial, and maybe unique, to find direct astrophysical probes of the existence and of the nature of Dark Matter, or to set strong experimental limits. © ESO 2007.