The Epoch of Reionization (EoR) marks the transition from a neutral to an ionized intergalactic medium (IGM). A key method to trace the rate of this transition is Lyman Alpha (Ly𝜶) emission from galaxies. The evolution of the IGM’s HI fraction can be inferred from Ly𝜶 observations due to its resonant nature and the damping of its emission. But to understand the effect of inter-galactic HI over...
The quest to discover galaxies beyond redshift z = 9 and probe their properties has been a key motivation for the development of the James Webb Space Telescope (JWST). Early spectroscopic campaigns using JWST NIRSpec have already validated photometric selections and allowed us to probe the physical conditions of galaxies in the early universe. Intriguingly, NIRSpec follow-up observations of...
During cosmic reionization, ionized regions gradually grew and overlapped in the IGM. Understanding when and how reionization happened is crucial for studying the early structure formation and the properties of first galaxies in the Universe. At z>5.5, the observed IGM optical depth shows a significant scatter, indicating an inhomogeneous reionization process. However, the nature of the...
Extremely overdense regions in the early Universe are likely engines for the production of hydrogen ionising radiation in the early Universe. The copious number of UV-faint galaxies and the idealistic environment for driving AGN activity means the most overdense environments, protoclusters, should drive some of the first ionised bubbles. As such, characterising the properties of these...
The rest-frame UV luminosity function (UV LF) and evolution thereof is a crucial component of understanding star formation in the early universe, and how star-forming galaxies contributed to cosmic reionization. Prior to JWST, the rate of decline of the UV LF at z > 8 was unclear, but early analyses of JWST data have suggested the presence of an unexpectedly large abundance of luminous...
Despite it being a fundamental milestone in our Universe’s evolution, the epoch of reionization (EoR) remains poorly understood. Luckily, recent years have witnessed a large increase both in observational datasets probing the EoR as well as sophisticated theoretical frameworks used to interpret this data. We introduce two novel, forward-modeling, implicit-likelihood inference frameworks...
The intergalactic medium damping wing signatures of the highest redshift quasars have been an effective tool in deciphering the epoch of reionization. However, only a handful have been discovered so far above redshift 7. In the near future, the Euclid mission will enable the discovery of an order of magnitude more quasars for damping wing studies. In light of this impending flood of new...
Measuring the size distribution of ionized bubbles is key to understanding the physical properties of early galaxies, including those too faint for even JWST to detect directly. How do we measure these ionized bubbles? How can we infer the properties of reionizing galaxies from the measured bubble sizes? Excitingly, JWST’s excellent capability of detecting Lyman-alpha emission lines from...
The influx of data from JWST, coupled with advancements in radiative transfer simulations, is improving our understanding of cosmic reionization. Recent findings suggest a late and rapid reionization model leads to the best fit to current observations. However, the identification of high-redshift AGNs and LAEs challenge these models, necessitating a reevaluation of AGNs and galaxies' roles in...
