Garrelt Mellema

TL;DR: In this article, a new upper limit on the 21 cm signal power spectrum at a redshift of z approximate to 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR).

TL;DR: In this article, the authors present numerical radiation-hydrodynamic simulations of the evolution of H II regions formed in an inhomogeneous medium resulting from turbulence simulations and find that the filamentary structure of the underlying density distribution produces a highly irregul ar shape for the ionized region, in which the ionization front escapes to large distances in some directions within 8 0,000 years, in other directions, on the other hand, neutral gas in the form of dense globules persists within 1 parsec of the central star for the full duration of their simulation (400,

TL;DR: In this paper, the authors present numerical radiation-hydrodynamic simulations of the evolution of HII regions formed in an inhomogeneous medium resulting from turbulence simulations, and find that the filamentary structure of the underlying density distribution produces a highly irregular shape for the ionized region, in which the ionization front escapes to large distances in some directions within 80,000 years.

TL;DR: In this article, the authors compare nine independent RT codes directly coupled to gas dynamics on three relatively simple astrophysical hydrodynamics problems: (i) the expansion of an H ii region in a uniform medium, (ii) an ionization front in a 1/r2 density profile with a flat core and (iii) the photoevaporation of a uniform dense clump.

TL;DR: In this article, the authors show that reionization began much earlier with minihalo sources than without, and was greatly extended, which boosts the intergalactic electron-scattering optical depth and the large-angle polarization fluctuations of the cosmic microwave background significantly.