ACP Seminar (Astronomy - Cosmology - Particle Physics)

Speaker: Chiaki Hikage (Nagoya U)
Title: Towards a precision cosmology with CMB and galaxy survey data
Date (JST): Thu, Feb 21, 2013, 14:00 - 15:00
Place: Seminar Room A
Abstract: Current CMB experiments and galaxy surveys provide hints for deviations from the standard Lambda CDM model, e.g., primordial non-Gaussianity (NG), massive neutrinos, and the effective neutrino number more than 3. Upcoming observations have potentials to detect such deviations significantly, however, one has to control systematics more carefully. I will talk about two topics to aim for eliminating systematic uncertainties by combining different measurements and different statistical methods.
1) One of major systematics in the analysis of galaxy redshift surveys comes from the challenge in modeling the relationship between galaxy redshift and underlying matter distribution known as redshift distortion. In particular, satellite galaxies produces the nonlinear redshift distortion effect, i.e., Finger-of-God (FoG), which complicates the interpretation of the galaxy power spectrum. I present a novel method to calibrate the FoG effect by combining lensing and correlation measurements and show the results applied to the SDSS galaxy dataset.
2) Uncertainty in foreground contaminations may bias the measurement of primordial NG from CMB. Consistency checks using different statistical methods are useful for finding systematics because different statistics are sensitive to different aspects of NG. I have constrained the primordial NG from WMAP data using Minkowski Functionals, which are sensitive to higher-order terms beyond the bispectrum. I will also present the CMB constraint on the non-Gaussian isocurvature perturbations.