Related papers: A Cosmic UV/X-ray Background Model Update
The cosmic ultraviolet (UV) ionizing background impacts the formation of dwarf galaxies in the low-redshift universe (z=3) by suppressing gas infall into galactic halos with circular velocities up to v(circ)=75 km/s. Using a…
The boundary conditions of the heliosphere are set by the ionization, density and composition of inflowing interstellar matter. Constraining the properties of the Local Interstellar Cloud (LIC) at the heliosphere requires radiative transfer…
Feedback from active galactic nuclei (AGN) is widely acknowledged to regulate the growth of massive galaxies, though its driving mechanisms are debated. Prevailing theories suggest that AGN-driven outflows are driven either by radiation…
A search for O VI at redshifts corresponding to Ly-alpha lines in the z_em ~ 2.4 QSOs HE1122-1648 and HE2217-2818 reveals that a substantial fraction of those with H I column densities log N(HI) > 14 (cm^{-2}) are highly ionized and show…
Using 3D radiative transfer calculations on the reionization of an inhomogeneous universe, QSO absorption line systems are simulated and they are compared with observations of Ly$\alpha$ continuum depression at high redshifts. By this…
Early results from the JWST observations have reported a surprisingly high number of UV-bright galaxies at $z \geq 10$, which appears to challenge the theoretical predictions from standard galaxy formation models in the $\Lambda$CDM…
We reassess constraints on the cosmological baryon density from observations of the mean decrement and power spectrum of the Lyman-alpha forest, taking into account uncertainties in all free parameters in the simplest gravitational…
We use deep and wide imaging data from the CFHT Large Area U-band Deep Survey (CLAUDS) and the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) to constrain the ionizing radiation (Lyman Continuum; LyC) escape fraction from AGNs at $z…
The Epoch of Reionization marks the last major phase transition in the early Universe, during which the majority of neutral hydrogen once filling the intergalactic medium was ionized by the first galaxies. The James Webb Space Telescope is…
In Paper III of our series "A Uniform Analysis of the Ly-alpha forest at z=0 - 5", we presented a set of 270 quasar spectra from the archives of the Faint Object Spectrograph on the Hubble Space Telescope. A total of 151 of these spectra,…
We use the recent detection of He II absorption at $z=2.2-2.6$ in the line of sight of the quasar HS1700+64 to put bounds on the sources of ionization. We find that given the uncertainty in $\tauhgp$ and the model of absorption in the…
We present spatially resolved gas kinematics, ionization, and energetics of 11 type 1 and 5 type 2 active galactic nuclei (AGNs) with strong ionized gas outflows at z $<0.3$ using Gemini Multi-Object Spectrograph Integral Field Unit…
Cosmic reionization is expected to be complex, extended and very inhomogeneous. Existing constraints at z~6 on the volume-averaged neutral hydrogen fraction, <x_HI>, are highly model-dependent and controversial. Constraints at z<6,…
Reionisation-era galaxies often display intense nebular emission lines, both in rest-frame optical ([OIII]+H$\beta$) and ultraviolet (UV; CIII], CIV). How such strong nebular emission is powered remains unclear, with both active galactic…
Next generation telescopes such as the James Webb Space Telescope (JWST) and the Nancy Grace Roman Space Telescope (NGRST) will enable us to study the first billion years of our Universe in unprecedented detail. In this work we use the…
The fraction of ionizing photons that escape from young star-forming galaxies is one of the largest uncertainties in determining the role of galaxies in cosmic reionization. Yet traditional techniques for measuring this fraction are…
We calibrate here cosmological radiative transfer simulation with ATON/RAMSES with a range of measurements of the Lyman alpha opacity from QSO absorption spectra. We find the Lyman alpha opacity to be very sensitive to the exact timing of…
Recently, Jakobsen et al. reported that the HeII Gunn-Peterson optical depth is greater than 1.7 at $ z=3.3$. When we consider this observation combined with the HI Gunn-Peterson optical depths and the intensity of the UV background at high…
We show that by jointly fitting cosmic microwave background (CMB) and astrophysical data - a compilation of UV luminosity data from the Hubble Frontier Field and neutral hydrogen data from distant sources-, we can infer on the shape of the…
A prediction of the classic active galactic nuclei (AGN) unification model is the presence of ionisation cones with different orientations depending on the AGN type. Confirmations of this model exist for present times, but it is less clear…