Searching for signatures of cosmic superstrings in the CMB

Abstract

Because cosmic superstrings generically form junctions and gauge theoreticstrings typically do not, junctions may provide a signature to distinguishbetween cosmic superstrings and gauge theoretic cosmic strings. Incosmic microwave background anisotropy maps, cosmic strings lead todistinctive line discontinuities. String junctions lead to junctionsin these line discontinuities. In turn, edge detection algorithms suchas the Canny algorithm can be used to search for signatures of stringsin anisotropy maps. We apply the Canny algorithm to simulated mapswhich contain the effects of cosmic strings with and without string junctions.The Canny algorithm produces edge maps. To distinguish betweenedge maps from string simulations with and without junctions, weexamine the density distribution of edges and pixels crossed by edges.We find that in string simulations without Gaussian noise (such asproduced by the dominant inflationary fluctuations) our analysisof the output data from the Canny algorithm can clearly distinguishbetween simulations with and without string junctions. In the presenceof Gaussian noise at the level expected from the current bounds on thecontribution of cosmic strings to the total power spectrum of densityfluctuations, the distinction between models with and without junctionsis more difficult. However, by carefully analyzing the data themodels can still be differentiated.