Gravitational Lensing Effect on the Two-point Correlation of Hotspots in the Cosmic Microwave Background

Masahiro Takada1, Eiichiro Komatsu1,2 and Toshifumi Futamase1

1. Astronomical Institute, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
2. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA


We investigate the weak gravitational lensing effect due to the large-scale structure of the universe on two-point correlations of local maxima ({\em hotspots}) in the 2D sky map of the cosmic microwave background (CMB) anisotropy. According to the Gaussian random statistics as most inflationary scenarios predict, the hotspots are discretely distributed with some {\em characteristic} angular separations on the last scattering surface owing to oscillations of the CMB angular power spectrum. The weak lensing then causes pairs of hotspots which are separated with the characteristic scale to be observed with various separations. We found that the lensing fairly smoothes the oscillatory features of the two-point correlation function of hotspots. This indicates that the hotspots correlations can be a new statistical tool for measuring shape and normalization of the power spectrum of matter fluctuations from the lensing signatures.