Elena Rasia, Stefano Borgani, Stefano Ettori, Pasquale Mazzotta, Massimo Meneghetti
[Abridged] Since fifteen years, the concentration-mass relation has been investigated diffusely in theoretical studies. On the other hand, only recently this relation has been derived from X-ray observations. When that happened, the results caused a certain level of concern: the X-ray normalizations and slopes were found significantly dissimilar from those predicted by theory. By analyzing a total of 52 objects, simulated each time with different physical recipes for the baryonic component, as well as 60 synthetic X-ray images, we aim at determining if these discrepancies are real or artificial. In particular, we investigate how the simulated concentration-mass relation depends i) on the radial range used to derive the concentration, ii) on the presence of baryons in the simulations, and on the prescription used to reproduce the gas. Finally, we evaluate iii) how the results differ when adopting an X-ray approach for the analysis and iv) how the selection functions based on X-ray luminosity, temperature, and SZ-signal can impact the results. All effects studied go in the direction of explaining the discrepancy between observations and simulations, but they contribute at different levels: while the fitting radial range and the baryonic component play only a minor role, the X-ray approach and selection function have profound repercussion on the results.
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http://arxiv.org/abs/1301.7476
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