Large Scale Structure: Its possible imprint on the CMB?

Abstract

We present the new results of the Jodrell-IAC Cosmic Microwave Background (CMB) anisotropy experiment for declination +40°. A similar level of sensitivity has been achieved with respect to the reported previous experiment at an angular scale of 8.8° in Davies et al. 1987. A positive temperature deviation of ≈ 0.3mK at 10.46GHz is identified at RA 14^h55^m; known point sources with flux densities greater than 6Jy are seen in other sections of the scan, but none are known at the position of the 14^h55^m feature. This feature appears, albeit weakly, in both the 5.6° and the 8.8° data. We note that this position coincides with that of the large void in Boötes (Kirshner et al. 1981) where it crosses δ = +40°. Also at this same position there appears an unusual string of galaxies, tentatively attributed by Tago et al. 1986, to the relic of a density singularity. It seems unlikely that the apparent level of anisotropy can be caused by these structures, at least by gravitational means alone, but there remains the possibility that the origin, apart from it being intrinsic to the CMB, could be galactic.