Related papers: Topology and Sizes of HII Regions during Cosmic Re…
The spatial morphology, spectral characteristics, and time variability of ultracompact H II regions provide strong constraints on the process of massive star formation. We have performed simulations of the gravitational collapse of rotating…
Gas metallicity $Z$ and the related dust-to-gas ratio $f_\textrm{d}$ can influence the growth of HII regions via metal line cooling and UV absorption. We model these effects in star-forming regions containing massive stars. We compute…
The accepted explanation of the observed dichotomy of two orders of magnitude between in situ measurements of electron density in HII regions, derived from emission line ratios, and average measurements based on integrated emission measure,…
Recent observations and simulations have suggested that HII regions around massive stars may vary in their size and emitted flux on timescales short enough to be observed. This variability can have a number of causes, ranging from…
We use cosmological simulations of reionization to predict the effect of large HII regions around individual high-redshift quasars on the possible signal from the redshifted 21cm line of neutral hydrogen in the pre-reionization era. We show…
We investigate the relationship of the HII region luminosity function (HII LF) to the HII region size distribution and density wave triggering in grand-design spiral galaxies. We suggest that the differential nebular size distribution is…
We explore the ability of measurements of the 21-cm power spectrum during reionization to enable the simultaneous reconstruction of the reionization history and the properties of the ionizing sources. For various sets of simulated 21-cm…
We present the first large-scale, full radiative transfer simulations of the reionization of the intergalactic medium in the presence of Lyman-limit systems (LLSs). To illustrate the impact of LLS opacity, possibly missed by previous…
Hypercompact HII regions (HC) are regions of ionized gas associated with the early stages of high-mass star formation. With the aim of better understanding their characteristics, we studied five candidate HC HII regions. Here, we present…
We present predictions for two statistical measures of the hydrogen reionization process at high redshift. The first statistic is the number of neutral segments identified in spectra of high redshift QSOs as a function of their length. The…
Recent measurements of the mean free path (MFP) of ionizing photons at $z=6$ find that it is significantly shorter than extrapolations from lower $z$. This has a substantial impact on the topology of reionization and thus the prospects of…
We present a new set of analytic models for the expansion of HII regions powered by UV photoionisation from massive stars and compare them to a new suite of radiative magnetohydrodynamic simulations of turbulent, self-gravitating molecular…
Recently the numerical simulations of the process of reionization of the universe at z>6 have made a qualitative leap forward, reaching sufficient sizes and dynamic range to determine the characteristic scales of this process. This allowed…
We present MUSE Integral Field Unit (IFU) observations of five individual HII regions in two giant (>100 pc in radius) star-forming complexes in the low-metallicity ($Z$~0.33 $Z_{\odot}$) nearby (D ~ 2 Mpc) dwarf spiral galaxy NGC 300. We…
We compute the bispectra of the 21cm signal during the Epoch of Reionization for three different reionization scenarios that are based on a dark matter N-body simulation combined with a self-consistent, semi-numerical model of galaxy…
We study the topology of the network of ionized and neutral regions that characterized the intergalactic medium during the Epoch of Reionization. Our analysis uses the formalism of persistent homology, which offers a highly intuitive and…
The HII regions are all studied employing the same general prescriptions, despite the possible influence of their environment in their star formation processes. Through the analysis of two samples of 725 inner and 671 outer disk HII region…
Context: How do expanding HII regions interact with their environmental cloud? This is one of the central questions driving the SOFIA legacy program FEEDBACK. Here, we present a case study toward the prototypical H{\sc ii} region NGC7538.…
Predicting the statistical properties of the neutral hydrogen (HI) density field during reionization is an important step in using upcoming 21 cm observations to constrain models of reionization. Semi-numerical models of reionization are…
The HI distribution at the epoch of reionization (EOR) is largely determined by the sizes and distribution of the ionized regions. In the scenario where the ionized regions have comoving sizes of the order of a few Mpc, the large scale…