Speaker

Aurélien Valade

AIP / CPPM

Abstract

The originality of the CLUES consortium is the producing of so-called constrained simulations, cosmolical that aim at reproducing the structure of the Local Universe. A key step in the making of simulations is the creation of constrained initial conditions, which are not only statistically consistent with the CMB but also contain the seeds of the structure that will evolve the low-redshift Local Universe. The traditional approach of the CLUES consortium relies on the Wiener Filter / Constrained Realization applied to the CosmicFlows catalogs of peculiar velocities. Yet, as data goes deeper, the assumptions behind the WF/CR methodology cease to be valid. This leads to the necessity to patch the data with so-called "correction techniques", whose designing might be seen as ad-hoc. We propose an new approach based on the full forward modeling of the problem: initial conditions are guessed, evolved to a low redshift universe and compared to the Cosmicflows data. A series of such initial conditions that are in agreement with the data is produced through an efficient Hamiltonian Monte Carlo algorithm. Our implementation, named HAMLET, has succesfully reconstructed the low-redshift matter distribution in the Local Universe from the Cosmicflows-4catalog using the linear theory. We are currently working on extending the model to generate jointly initial conditions as well as non-linear, low-redshift maps evolved with a 2nd order Lagrangian pertubation method.

Scientific theme

Initial conditions, constrained simulations, forward modeling