From Light to Insight: Mapping the Evolving Universe with Transport of Cosmic Radiation

Synopsis

In this seminar, I will discuss how astrophysicists probe two important aspects of the Universe - magnet fields and gas reionization - on its largest scales. 

Beginning with an overview of recent theoretical and observational advancements in both areas, I will highlight the major challenges as well as exciting opportunities they present. Following this, I will present a solution that bridges theory and observations for each field using a covariant formalism of cosmological radiative transfer (CRT), which is derived from conservation laws of physics, to models how radiative properties changes and propagates in an expanding, evolving Universe. The CRT framework surpasses the limitations of traditional methods by enabling self-consistent treatments of global and local processes and precise calculations of cosmic signals, thereby providing a concrete foundation to probe large-scale cosmic magnetism and reionization. 

I will demonstrate

• How the CRT of polarized continuum radiation can interface with cosmological magneto-hydrodynamics (MHD) simulation results to generate high-fidelity polarization maps, which are crucial to aid the interpretation of observational data, such as those to be collected by SKA and its precursors (e.g. ASKAP) & pathfinders (e.g. LOFAR);  
• How the CRT of the 21-cm line of neutral hydrogen allows us to properly calculate the line signals of the cosmic Dark Ages, Cosmic Dawn and the Epoch of Reionisation (i.e. when the Universe proceeded from a neutral phase to an ionised phase), which are targeted by experiments such as HERA and SKA. 

I will conclude this talk by summarizing what the CRT formalism of the two types of radiation offers and how it can bring new insights to our understanding of the evolving Universe, leveraging the extensive data resources from simulations and observations.