Predictions on the angular power spectrum of clustered extragalactic point sources at CMB frequencies from flat and all--sky 2D-simulations

摘要

We present predictions on the angular power spectrum of CMB fluctuations dueto extragalactic point sources (EPS) by using a method for simulating realistic2D distributions of clustered EPS. Both radio and far--IR selected sourcepopulations are taken into account. To analyze different clustering scenarios,we exploit angular power spectra of EPS, $P(k)$, estimated either by datacoming from currently available surveys or by means of theoretical predictions.By adopting the source number counts predicted by the Toffolatti et al. (1998)evolution model -- capable of accounting well for the available data at radiocm wavelengths -- we are able to reproduce current data on the two--pointangular correlation functions, $w(heta)$, of radio sources. We can confirmthat the detection of primordial CMB anisotropies is not hampered by undetectedclustered sources at frequencies $leq 150-200$ GHz. On the other hand, ourcurrent findings show that at higher frequencies the clustering signal couldseverely reduce the detectability of intrinsic CMB anisotropies, thusconfirming previous theoretical predictions. We also show that unsubtracted EPScan account for the excess signal at high multipoles detected by recent CMBanisotropy experiments. Moreover, the additional power due to the clustering ofsources gives rise to a small but not negligible contribution to the sameexcess signal. As a final result, we also present an example of a currentlyfeasible {it realistic map} of EPS at 70 GHz, by taking into account data onbright detected sources as well as the previously quoted model for numbercounts.