Colloquium on Oct. 25th, 2019

Constraining neutrino mass and dark energy with peculiar velocities and lensing dispersions of Type Ia supernovae

Speaker: Toshi Futamase (Tohoku Univ.)

Venue: Room 2111, SWIFAR Building

Time: 3:30 PM, Friday, 25th October, 2019

Abstract:

Large scale structure of the universe causes noises in the measurement of the cosmological parameters. At the same time it carries important information in cosmology. As an example I consider such noises in the magnitude-redshift relation of type Ia supernovae. Namely I show that peculiar velocities and the lensing effect in the measurement of Type Ia supernovae can be used to constrain the sum of neutrino masses, Σm_ν, and dark energy equation of state, w=w_0+w_a (1- a). At low redshifts, the peculiar velocity signal dominates while at high redshifts lensing does. I show that using lensing and peculiar velocity of supernovae from the upcoming surveys WFIRST and ZTF, without other observations,we can constrain Σm_ν< 0.31 eV, σ(w_0)<0.02 , and σ(w_a)<0.18  (1σ  CL) in the  Σm_ν-w 0 -w a  parameter space, where all the other cosmological parameters are fixed. We find that adding peculiar velocity information from low redshifts shrinks the volume of the parameter ellipsoid in this space by 〜33 %.