2019

First Star-Forming Structures in Fuzzy Cosmic Filaments

by Dr Phil Mocz (Princeton)

Pacific/Honolulu
417A (Watanabe Hall)

417A

Watanabe Hall

Description

In hierarchical models of structure formation, the first galaxies form in low mass dark matter potential wells, probing the behavior of dark matter on kiloparsec (kpc) scales. Even though these objects are not observed today, telescopes such as the James Webb Space Telescope (JWST) will soon offer an observational window into this emergent world. In this talk I describe how the first galaxies are assembled in a `fuzzy' dark matter (FDM) cosmology where dark matter is an ultralight ~10^-22 eV boson and the primordial stars are expected to form along dense dark matter filaments. Using a first-of-its-kind cosmological hydrodynamical simulation, we explore the interplay between baryonic physics and unique wavelike features inherent to FDM. In our simulation, the dark matter filaments show coherent interference patterns on the boson de Broglie scale, develop cylindrical soliton-like cores, and form stars along the entire structure. The filaments are unstable under gravity and collapse into kpc-scale spherical solitons. Features of the dark matter distribution are largely unaffected by the realistic baryonic feedback; on the contrary, gas and stars follow dark matter filaments and their profiles exhibit flattened cores -- smoking gun signatures of FDM. I contrast these results against first structures in cold and warm dark matter cosmologies.