Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Efficient adiabatic hydrodynamical simulations of the high-redshift
  intergalactic medium   We present a post-processing tool for GADGET-2 adiabatic simulations to model
various observed properties of the Ly$\alpha$ forest at $2.5 \leq z \leq 4$
that enables an efficient parameter estimation. In particular, we model the
thermal and ionization histories that are not computed self-consistently by
default in GADGET-2. We capture the effect of pressure smoothing by running
GADGET-2 at an elevated temperature floor and using an appropriate smoothing
kernel. We validate our procedure by comparing different statistics derived
from our method with those derived using self-consistent simulations with
GADGET-3. These statistics are: line of sight density field power spectrum,
flux probability distribution function, flux power spectrum, wavelet
statistics, curvature statistics, HI column density (${\rm N_{HI}}$)
distribution function, linewidth ($b$) distribution and $b$ versus $\log {\rm
N_{HI}}$ scatter. For the temperature floor of $10^4$ K and typical
signal-to-noise of 25, the results agree well within 20 percent of the
self-consistent GADGET-3 simulation. However, this difference is smaller than
the expected $1\sigma$ sample variance for an absorption path length of $\sim
5.35$ at $z=3$. Moreover for a given cosmology, we gain a factor of $\sim N$ in
computing time for modelling the intergalactic medium under $N \gg 1$ different
thermal histories. In addition, our method allows us to simulate the
non-equilibrium evolution of thermal and ionization state of the gas and
include heating due to non-standard sources like cosmic rays and high energy
$\gamma$-rays from Blazars.

2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph