Francisco-Shu Kitaura

 

My interest is to understand how the Universe evolves, how it forms structures, why it expands, and what is the nature of dark matter and dark energy. These belong to the major questions in modern cosmology. My aim is to bridge the gaps between theory, simulations, and observations. I have accumulated a vast expertise in cosmological perturbation theory, numerical simulations, statistical inference techniques, and galaxy surveys, making a large number of ground-breaking contributions in different fields.

Based on the main sample of the Sloan Digital Sky Survey (SDSS), I started working on unprecedented dark matter field reconstructions, which lead to the discovery of a super-void and to the accurate study of the dark matter statistics.

Later, I have done several important contributions to perturbation theory developing nonlinear techniques relating the density to the velocity field, and developing accurate fast structure formation models (augmented Lagrangian perturbation theory: ALPT). I have moreover integrated these methods in a statistical Bayesian framework to reconstruct density fields, velocity fields, and the primordial fluctuations of the Universe from a distribution of galaxies (being the main developer of the ARGO and KIGEN codes).

These techniques have enabled me to study the cosmic web structure and dynamics of the Local Universe (LU) with unprecedented accuracy in a series of works based on observational data from the Two-Micron All-Sky Redshift Survey. These included the first self-consistent full nonlinear constrained (N-body) simulations. Based on the reconstructions of the LU (using the KIGEN code) I worked on a number of astrophysical problems:

 

• the Local Group velocity of galaxies including our Milky Way (the CMB-dipole problem),

• the local expansion of the Universe (the Hubble constant),

• the peculiar voids and clusters in the LU testing the cosmological paradigm (confirming ΛCDM in the LU, solving the missing matter problem in the LU),

• the galaxy morphology and environmental relation (including spiral, elliptical, irregular, and extremely metal poor galaxies),

• and the baryon content in the filamentary network connecting groups of galaxies (the missing baryons problem).

• The velocity reconstructions based on the central galaxy catalogue from the SDSS, to which I contributed, lead to a significant detection of the kinematic Sunyaev Zeldovich effect, accounting for the missing baryons around central galaxies (including one Planck collaboration paper).

 

An investigation of large N-body simulations permitted me to extract effective halo and galaxy bias models (including nonlinear, nonlocal, and stochastics bias components). This lead to the first inference methods including non-Poisson clustering of haloes and galaxies (ARGO), and to accurate efficient methods to produce halo and galaxy catalogues (being the main developer of the PATCHY code). These methods have been used to produce the largest ever simulated galaxy catalogues including precise two and three point clustering for the SDSS Baryon Oscillation Spectroscopic Survey final data release, which have been used to study the scale of the Universe (baryon acoustic oscillations), and gravity (growth rate through redshift space distortions).

 

In addition, at the early stages of my career I produced the first natural simulations of neu- trino driven Supernova explosions based on a hydrodynamical neutrino Boltzman transport code including a detailed micro-physics description.

As the principal investigador (PI) of the cosmology science case for 4MOST, the co-lead of the baryon acoustic oscillations reconstruction working group for EUCLID, and the co-lead of the data analysis working group for J-PAS, I plan to further develop optimal methods for the analysis of the cosmological large-scale structure, which permit to unveil major scientific questions in the formation and origin of our Universe.