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Abstract: We explore for the first time the method of cross-correlation of radiosynchrotron emission and tracers of large-scale structure in order to detectthe diffuse IGM-WHIM. We performed a cross-correlation of a 34 x 34 degree areaof 2MASS galaxies for two redshift slices 0.03 < z < 0.04 and 0.06 < z < 0.07with the corresponding region of the 1.4 GHz Bonn survey. For this analysis, weassumed that the synchrotron surface brightness is linearly proportional tosurface density of galaxies. We also sampled the cross-correlation functionusing 24 distant fields of the same size from the Bonn survey, to better assessthe noise properties. Though we obtained a null result, we found that by addinga signal weighted by the 2MASS image with a filament peak surface brightnessof 1 7 mK and 7 49 mK would produce a 3 sigma positive correlation for the0.03 < z < 0.04 and 0.06 < z < 0.07 redshift slices respectively. Thesedetection thresholds correspond to minimum energy magnetic fields as low as 0.2microG, close to some theoretical expectations for filament field values. Thisinjected signal is also below the rms noise of the Bonn survey, anddemonstrates the power of this technique and its utility for upcoming sensitivecontinuum surveys such as GALFACTS at Arecibo and those planned with theMurchison Widefield Array MWA.



Autor: Shea Brown, Damon Farnsworth, Lawrence Rudnick

Fuente: https://arxiv.org/



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