New Paper: Stochastic Reionization from the Smallest Galaxies

Also last week, we submitted a paper, led by Pengfei Chen (now in the finance sector), on the stochastic nature of reionization during its initial phases. Here we used the galactic properties from the Renaissance Simulations as the source model in a reionization simulation. We find that before a redshift of 10 (age of the universe = 500 million years), small galaxies dominate, whose ionized regions are stochastically flicker because of the burstiness of the first galaxies. After that time, larger galaxies that have more steady star formation dominate the ionizing photon budget and contribute the majority of the photons to reionization.

New Paper: Turbulent accretion onto black holes

Last week, our paper (arXiv), led by KwangHo Park, on the behavior of accretion flows onto intermediate mass black holes was submitted to the Astrophysical Journal. Here we used 3D radiation hydrodynamics simulations to study how the surrounding environment is affected by radiation feedback that originates from the gas around the black hole. We found that the accretion rates are oscillatory in nature, agreeing with previous 1D and 2D simulations, but these bursts induce turbulence, which can enhance black hole growth rates during quiescent phases. Although turbulent energy does not dominate the energy budget, it plays a key role in the regulation of black hole fueling.