Takashi Hiramatsu (Kyoto University, Japan)
Cosmic Microwave Background (CMB) is known as a remnant of Big-Bang, and lots of past works in cosmology have paid attention to its potential to prove the very early Universe. In these days, our main interests moved to quite fine structures of the Universe, for instance, the statistical properties of the primordial fluctuations constructing the large-scale structure, and in fact we can investigate them thanks to rapid and sophisticated development of observational technologies. The simplest way to quantify the non-trivial statistical properties of the fluctuations is to calculate their bispectrum, or three-point correlation function. In our previous work, we developed a novel formalism, curve-of-sight formula, to compute the bispectrum of CMB temperature fluctuations in JCAP 10 (2014) 051, and have been developing a new Boltzmann solver implementing the curve-of-sight formula. In this talk, we show the up-to-date numerical results of the CMB bispectrum using the curve-of-sight formula, and also report the current status of the development of our numerical code aiming at solving the 2nd-order Boltzmann equations.