Kavli Affiliate: George Efstathiou
| First 5 Authors: Jiten Dhandha, Thomas Gessey-Jones, Harry T. J. Bevins, Simon Pochinda, Anastasia Fialkov
| Summary:
In the current era of JWST, we continue to uncover a wealth of information
about the Universe deep into the Epoch of Reionization. In this work, we run a
suite of simulations using the code 21cmSPACE, to explore the astrophysical
properties of galaxies in the early Universe, and their impact on high-redshift
observables. We use multi-wavelength observational data including the global
21-cm signal and power spectrum limits from SARAS~3 and HERA respectively,
present-day diffuse X-ray and radio backgrounds, and UV luminosity functions
(UVLFs) from HST and JWST in the range $z=6-14.5$ to derive our constraints. We
constrain a flexible model of halo-mass and redshift dependent star-formation
efficiency (SFE), defined as the gas fraction converted into stars, and find
that it is best described by little to no redshift evolution at $zapprox6-10$
and rapid evolution at $zapprox10-15$. We derive Bayesian functional posterior
distributions for the SFE across this redshift range, inferring that a halo of
mass $M_h=10^{10}text{M}_odot$ has an efficiency of $2-3%$ at $zlesssim10$,
$12%$ at $z=12$ and $26%$ at $z=15$. We also find, through synergy between
SARAS~3 and UVLFs, that the minimum circular velocity for star-formation in
halos is $V_c = 16.9^{+25.7}_{-9.5}text{km s}^{-1}$ or equivalently
$log_{10}(M_text{crit}/text{M}_odot) = 8.29^{+1.21}_{-1.08}$ at $z=6$.
Alongside these star-formation constraints, we find the X-ray and radio
efficiencies of early galaxies to be $f_X = 0.5^{+6.3}_{-0.3}$ and $f_r
lesssim 11.7$ respectively, improving upon existing works that do not use UVLF
data. Our results demonstrate the critical role of UVLFs in constraining the
early Universe, and its synergies with 21-cm observations, alongside other
multi-wavelength observational datasets.
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