AMBER: A Semi-numerical Abundance Matching Box for the Epoch of
  Reionization
  The Abundance Matching Box for the Epoch of Reionization (AMBER) is a
semi-numerical code for modeling the cosmic dawn. The new algorithm is not
based on the excursion set formalism for reionization, but takes the novel
approach of calculating the reionization-redshift field
$z_\mathrm{re}(\boldsymbol{x})$ assuming that hydrogen gas encountering higher
radiation intensity are photoionized earlier. Redshift values are assigned
while matching the abundance of ionized mass according to a given mass-weighted
ionization fraction $\bar{x}_\mathrm{i}(z)$. The code has the unique advantage
of allowing users to directly specify the reionization history through the
redshift midpoint $z_\mathrm{mid}$, duration $\Delta_\mathrm{z}$, and asymmetry
$A_\mathrm{z}$ input parameters. The reionization process is further controlled
through the minimum halo mass $M_\mathrm{min}$ for galaxy formation and the
radiation mean free path $l_\mathrm{mfp}$ for radiative transfer. We implement
improved methods for constructing density, velocity, halo, and radiation
fields, which are essential components for modeling reionization observables.
We compare AMBER with two other semi-numerical methods and find that our code
more accurately reproduces the results from radiation-hydrodynamic simulations.
The parallelized code is over four orders of magnitude faster than radiative
transfer simulations and will efficiently enable large-volume models, full-sky
mock observations, and parameter-space studies. AMBER will be made publicly
available to facilitate and transform studies of the EoR.
