We present CAMELS-ASTRID, the third suite of hydrodynamical simulations in
the Cosmology and Astrophysics with MachinE Learning (CAMELS) project, along
with new simulation sets that extend the model parameter space based on the
previous frameworks of CAMELS-TNG and CAMELS-SIMBA, to provide broader training
sets and testing grounds for machine-learning algorithms designed for
cosmological studies. CAMELS-ASTRID employs the galaxy formation model
following the ASTRID simulation and contains 2,124 hydrodynamic simulation runs
that vary 3 cosmological parameters ($\Omega_m$, $\sigma_8$, $\Omega_b$) and 4
parameters controlling stellar and AGN feedback. Compared to the existing TNG
and SIMBA simulation suites in CAMELS, the fiducial model of ASTRID features
the mildest AGN feedback and predicts the least baryonic effect on the matter
power spectrum. The training set of ASTRID covers a broader variation in the
galaxy populations and the baryonic impact on the matter power spectrum
compared to its TNG and SIMBA counterparts, which can make machine-learning
models trained on the ASTRID suite exhibit better extrapolation performance
when tested on other hydrodynamic simulation sets. We also introduce extension
simulation sets in CAMELS that widely explore 28 parameters in the TNG and
SIMBA models, demonstrating the enormity of the overall galaxy formation model
parameter space and the complex non-linear interplay between cosmology and
astrophysical processes. With the new simulation suites, we show that building
robust machine-learning models favors training and testing on the largest
possible diversity of galaxy formation models. We also demonstrate that it is
possible to train accurate neural networks to infer cosmological parameters
using the high-dimensional TNG-SB28 simulation set.

本文介绍了 CAMELS-ASTRID 项目中的第三套宇宙学和天体物理学的水动力学模拟以及新的模拟集，以此来为针对宇宙学研究的机器学习算法提供更广泛的训练和测试基础；该项目通过引入新的参数和其它宇宙和物理因素来扩展先前的框架，并仔细调查机器学习模型的行为。

CAMELS 项目：使用新的 ASTRID、28 参数 TNG 和 SIMBA 套件扩展星系形成模型空间

The CAMELS project: Expanding the galaxy formation model space with new  ASTRID and 28-parameter TNG and SIMBA suites

We introduce the Virgo Consortium's EAGLE project, a suite of hydrodynamical
simulations that follow the formation of galaxies and black holes in
representative volumes. We discuss the limitations of such simulations in light
of their finite resolution and poorly constrained subgrid physics, and how
these affect their predictive power. One major improvement is our treatment of
feedback from massive stars and AGN in which thermal energy is injected into
the gas without the need to turn off cooling or hydrodynamical forces, allowing
winds to develop without predetermined speed or mass loading factors. Because
the feedback efficiencies cannot be predicted from first principles, we
calibrate them to the z~0 galaxy stellar mass function and the amplitude of the
galaxy-central black hole mass relation, also taking galaxy sizes into account.
The observed galaxy mass function is reproduced to $\lesssim 0.2$ dex over the
full mass range, $10^8 < M_*/M_\odot \lesssim 10^{11}$, a level of agreement
close to that attained by semi-analytic models, and unprecedented for
hydrodynamical simulations. We compare our results to a representative set of
low-redshift observables not considered in the calibration, and find good
agreement with the observed galaxy specific star formation rates, passive
fractions, Tully-Fisher relation, total stellar luminosities of galaxy
clusters, and column density distributions of intergalactic CIV and OVI. While
the mass-metallicity relations for gas and stars are consistent with
observations for $M_* \gtrsim 10^9 M_\odot$, they are insufficiently steep at
lower masses. The gas fractions and temperatures are too high for clusters of
galaxies, but for groups these discrepancies can be resolved by adopting a
higher heating temperature in the subgrid prescription for AGN feedback. EAGLE
constitutes a valuable new resource for studies of galaxy formation.

介绍了 Virgo Consortium 的 EAGLE 项目，该项目是关于宇宙中星系和黑洞形成的一系列计算机模拟。在模拟结果中，我们得到了与半分析模型相当接近的星系质量分布，同时还模拟了与观测相符合的星系特定的星形成率，无活力星系的比例，等等。

EAGLE 项目：模拟星系的演化和组合及其环境

The EAGLE project: Simulating the evolution and assembly of galaxies and  their environments

We introduce the Illustris Project, a series of large-scale hydrodynamical
simulations of galaxy formation. The highest resolution simulation,
Illustris-1, covers a volume of $(106.5\,{\rm Mpc})^3$, has a dark mass
resolution of ${6.26 \times 10^{6}\,{\rm M}_\odot}$, and an initial baryonic
matter mass resolution of ${1.26 \times 10^{6}\,{\rm M}_\odot}$. At $z=0$
gravitational forces are softened on scales of $710\,{\rm pc}$, and the
smallest hydrodynamical gas cells have an extent of $48\,{\rm pc}$. We follow
the dynamical evolution of $2\times 1820^3$ resolution elements and in addition
passively evolve $1820^3$ Monte Carlo tracer particles reaching a total
particle count of more than $18$ billion. The galaxy formation model includes:
primordial and metal-line cooling with self-shielding corrections, stellar
evolution, stellar feedback, gas recycling, chemical enrichment, supermassive
black hole growth, and feedback from active galactic nuclei. At $z=0$ our
simulation volume contains about $40,000$ well-resolved galaxies covering a
diverse range of morphologies and colours including early-type, late-type and
irregular galaxies. The simulation reproduces reasonably well the cosmic star
formation rate density, the galaxy luminosity function, and baryon conversion
efficiency at $z=0$. It also qualitatively captures the impact of galaxy
environment on the red fractions of galaxies. The internal velocity structure
of selected well-resolved disk galaxies obeys the stellar and baryonic
Tully-Fisher relation together with flat circular velocity curves. In the
well-resolved regime the simulation reproduces the observed mix of early-type
and late-type galaxies. Our model predicts a halo mass dependent impact of
baryonic effects on the halo mass function and the masses of haloes caused by
feedback from supernova and active galactic nuclei.

介绍 Illustris 项目，该项目是一系列的大规模宇宙形成的水动力学模拟。模拟覆盖了一个体积为（106.5 Mpc）^3 的宇宙，包括星体演化、气体再循环、化学丰富、中子星和超大质量黑洞的影响等。模拟结果很好地再现了宇宙中的星体形成率密度、星系亮度函数和盘状星系的内部速度结构。