Research Theme: Cosmology and Gravity

With the development of observational techniques over the past few decades, the research on cosmology has made enormous progress. By exploiting observational data, it is now possible to probe the physics like

Evolution of the early universe based on quantum gravity and string theory

Growth of primordial density perturbations for the origins of Cosmic Microwave Background (CMB) temperature anisotropies and large-scale structures

Dark energy and dark matter

Black holes, neutron stars, and gravitational waves

In our lab, we are working on a wide variety of research topics related to cosmology and general relativity listed below.

Construction of theoretically consistent inflationary models and their observational constraints 　　

Particle production in the early Universe

CMB temperature anisotropies

Dark matter and growth of large-scale structures

Dark energy—construction of theoretical models and observational constraints

Extended theories of gravity and their observational signatures

Physics of black holes and neutron stars, and testing the regime of strong gravity through gravitational waves

In particular, we probe the physics in the early Universe like inflation by using the latest observational data of CMB. We also try to understand the source for late-time cosmic acceleration from the theoretical viewpoint and place constraints on dark energy models from observational data including supernovae type-Ia and CMB (see the figure below). The underlying physics of two epochs of cosmic acceleration in the early and late Universe has not been completely understood yet, so we would like to approach the origins of them by using numerous observational data including gravitational waves first detected in 2015. Ultimately, we aim to construct a viable cosmological model consistent with observations in theories beyond General Relativity and Standard Model of particle physics.