Related papers: The Shocking Truth: The small contribution to hydr…
The cosmic microwave background provides an image of the Universe 0.4 million years after the big bang, when atomic hydrogen formed out of free electrons and protons. One of the primary goals of observational cosmology is to obtain…
Cosmological shock waves play a major role in heating baryonic gas in the large scale structure of the universe. In this contribution we study the shock-heated gas in connection with shocks themselves. The distributions of shock speed and…
While most of the inter-galactic medium (IGM) today is permeated by ionized hydrogen, it was largely filled with neutral hydrogen for the first 700 million years after the Big Bang. The process that ionized the IGM (cosmic reionization) is…
We present self-consistent radiation hydrodynamic simulations of hydrogen reionization performed with Arepo-RT complemented by a state-of-the-art galaxy formation model. We examine how photoheating feedback, due to reionization, shapes the…
Models and simulations of the epoch of reionization predict that spectra of the 21-cm transition of atomic hydrogen will show a clear fluctuation peak, at a redshift and scale, respectively, that mark the central stage of reionization and…
We use a large set of hydrodynamical simulations, combined with measurements of the Lyman alpha opacity of the IGM taken from the literature, to obtain robust estimates for the photoionization rate per hydrogen atom at z=5 and 6. We find…
We present the first simulations of the formation and feedback of massive stars which account for radiation forces as well as photoionization feedback (along with protostellar outflows). In two different accretion scenarios modeled, we…
The part played by stars in the ionization of the intergalactic medium remains an open question. A key issue is the proportion of the stellar ionizing radiation that escapes the galaxies in which it is produced. Spectroscopy of gamma-ray…
The fraction of hydrogen ionizing photons escaping from galaxies into the intergalactic medium is a critical ingredient in the theory of reionization. We use two zoomed-in, high-resolution (4 pc), cosmological radiation hydrodynamic…
Deep surveys with the James Webb Space Telescope (JWST) have revealed an emergent population of moderate-luminosity, broad-line active galactic nuclei (AGNs) at 4< z< 14 powered by accretion onto early massive black holes. The high number…
The fraction of ionizing photons which escape their host galaxy and so are able to ionize hydrogen in the inter-galactic medium (IGM) is a critical parameter in studies of the reionization era and early galaxy formation. In this paper we…
We present a first study of the effect of local photoionising radiation on gas cooling in smoothed particle hydrodynamics simulations of galaxy formation. We explore the combined effect of ionising radiation from young and old stellar…
As a cold dark matter candidate, the QCD axion may form Bose-Einstein condensates, called axion stars, with masses around $10^{-11}\,M_{\odot}$. In this paper, we point out that a brand new astrophysical object, a Hydrogen Axion Star (HAS),…
In this paper I will discuss the possibility of a reionization of the Universe due to the photons emitted by evaporating primordial black holes (PBHs); this process should happen during the last stages of the PBHs life, when the particle…
With improving telescopes, it may now be possible to observe the Epoch of Reionization in multiple ways. We examine two of these observables - the excess light in the near-infrared background that may be due to high redshift stars and…
(Abridged) We review recent observations that suggest the star formation rate density is declining over 3$<z<$7 and illustrate the challenges that this poses in explaining the assembled stellar mass in z$\sim$6 galaxies deduced from Spitzer…
A deep understanding of the Epoch of Reionization is still missing in our knowledge of the universe. While future probes will allow us to test the precise evolution of the free electron fraction from redshifts between $z\simeq 6$ and…
The anomalous bump in the cosmic ray positron to electron ratio at $10 GeV$ can be explained as being a component from a point source that was originally harder than the primary electron background and degrades due to synchrotron and…
Galactic outflows are believed to play an important role in regulating star formation in galaxies, but estimates of the outflowing mass and momentum have historically been based on uncertain assumptions. Here, we measure the mass, momentum,…
A field with particularly exciting results over the past few years is the study of the interaction of cosmic rays with interstellar matter. For star formation to take place, gas and dust need to be sufficiently cold for gravity to overcome…