Understanding the epochs of cosmic dawn and reionisation requires us to
leverage multi-wavelength and multi-tracer observations, with each dataset
providing a complimentary piece of the puzzle. To interpret such data, we
update the public simulation code, 21cmFASTv4, to include a discrete source
model based on stochastic sampling of conditional mass functions and
semi-empirical galaxy relations. We demonstrate that our new galaxy model,
which parametrizes the means and scatters of well-established scaling
relations, is flexible enough to characterize very different predictions from
hydrodynamic cosmological simulations of high-redshift galaxies. Combining a
discrete galaxy population with approximate, efficient radiative transfer
allows us to self-consistently forward-model galaxy surveys, line intensity
maps (LIMs), and observations of the intergalactic medium (IGM). Not only does
each observable probe different scales and physical processes, but
cross-correlation will maximise the information gained from each measurement by
probing the galaxy-IGM connection at high-redshift. We find that a stochastic
source field produces significant shot-noise in 21cm and LIM power spectra.
Scatter in galaxy properties can be constrained using UV luminosity functions
and/or 21cm power spectra, especially if astrophysical scatter is higher than
expected (as might be needed to explain recent JWST observations). Our
modelling pipeline is both flexible and computationally efficient, facilitating
high-dimensional, multi-tracer, field-level Bayesian inference of cosmology and
astrophysics during the first billion years.

Este artículo explora los viajes en el tiempo y sus implicaciones.

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