Magneticum Pathfinder: Cosmological Simulations

• Magneticum Pathfinder is a suite of hydrodynamical cosmological simulations tracking the evolution of dark matter, gas, stars, and supermassive black holes.
• It employs multiple resolution tiers and advanced SPH methods to study galaxy clusters, scaling relations, and the cosmic web in a unified framework.
• The simulation suite is uniquely tuned to the hot gas content of clusters, enabling realistic matches to observed SZ profiles and galaxy evolution trends.

Magneticum Pathfinder is a suite of hydrodynamical cosmological simulations designed to follow the joint evolution of dark matter, gas, stars, and supermassive black holes from early times to the present day. In the 2025 synthesis of the project, it is described as the suite that “self-consistently covers the largest range in box volumes and resolutions” and as the only cosmological simulation suite “tuned on the hot gas content of galaxy clusters instead of the stellar mass function,” with galaxy properties and scaling relations then emerging within the same framework (Dolag et al., 1 Apr 2025).

1. Programme architecture and numerical scope

The main Magneticum runs adopt a WMAP-7 flat $\Lambda$CDM cosmology with

$$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$

This common cosmological setup underlies applications ranging from satellite systems and galaxy stellar halos to groups, clusters, and thermal SZ light-cones (Dolag et al., 1 Apr 2025).

A distinctive feature of the programme is its use of multiple periodic volumes at fixed resolution tiers, conventionally denoted mr, hr, uhr, and xhr. The 2025 overview gives the following box structure.

Box	Side length	Resolution level
Box0	3820 Mpc	mr
Box1a	1300 Mpc	mr
Box2b	910 Mpc	hr
Box2	500 Mpc	hr
Box3	180 Mpc	hr / uhr
Box4	68 Mpc	uhr
Box5	26 Mpc	xhr

For these tiers, representative particle masses and softenings are explicitly tabulated. In mr,

$$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$

with $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$ and $\epsilon_* = 5~h^{-1}{\rm kpc}$. In hr,

$$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$

with $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$ and $\epsilon_* = 2~h^{-1}{\rm kpc}$. In uhr,

$$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$

with $\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$ and $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$0. In xhr,

$$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$1

with $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$2 and $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$3 (Dolag et al., 1 Apr 2025).

Published applications illustrate how these boxes are used. Box2b/hr is employed for environmental statistics of AGN and star formation in cluster populations over a $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$4 comoving volume, while Box4(uhr) is used for high-resolution studies of planes of satellite galaxies and of tidal shells and streams (Rihtaršič et al., 2023, Förster et al., 2022, Stoiber et al., 29 Sep 2025). This combination of very large cosmological volumes and smaller ultra-high-resolution runs is central to the project’s division of labor across scales.

2. Numerical framework and baryonic physics

Magneticum is built on GADGET-3 or closely related P-GADGET3/P-Gadget3-XXL branches. The hydrodynamics is SPH-based, with later programme summaries emphasizing an entropy-conserving formulation, a Wendland $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$5 kernel with 295 neighbours, time-dependent viscosity, time-dependent artificial conductivity, a wake-up scheme for time stepping, and isotropic thermal conduction at $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$6 of Spitzer (Dolag et al., 1 Apr 2025). Other papers in the suite describe the implementation as an improved SPH formulation with high-order kernels, improved artificial viscosity, and artificial conduction, specifically for realistic ICM and galaxy-gas dynamics (Biffi et al., 2021).

The baryonic model includes radiative cooling, UV/X-ray background heating, star formation in a multiphase ISM, stellar feedback, chemical enrichment, black-hole growth, and AGN feedback. Across the published descriptions, the recurring ingredients are radiative cooling following Wiersma et al. (2009), the Springel & Hernquist (2003) multiphase ISM star-formation model, stellar evolution with a Chabrier IMF, enrichment from SNII, SNIa, and AGB stars, and quasar/radio-mode AGN feedback (Rihtaršič et al., 2023, Dolag et al., 2017, Dolag et al., 2015).

The star-formation law is implemented volumetrically, but the suite summary states that for resolved disks it reproduces a Kennicutt–Schmidt-type surface-density scaling,

$$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$7

The same overview notes that each gas particle can spawn up to four star particles, so the effective stellar mass resolution exceeds the gas-particle resolution (Dolag et al., 1 Apr 2025).

The black-hole model is a major organizing feature. In the fiducial implementation, seed black holes of

$$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$8

are inserted in halos whose stellar mass exceeds $$\Omega_{\mathrm{m}} = 0.272,\quad \Omega_{\mathrm{b}} = 0.0456,\quad \Omega_{\Lambda} = 0.728,\quad h = 0.704,\quad \sigma_8 = 0.809,\quad n_s = 0.963.$$9, and their gas accretion follows a Bondi–Hoyle–Lyttleton form,

$$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$0

capped at the Eddington rate (Dolag et al., 1 Apr 2025). In the SZ analysis the same family of prescriptions is written as

$$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$1

with $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$2, radiative efficiency $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$3, and a two-mode AGN feedback model in which the radio mode is activated below $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$4 (Dolag et al., 2015). An advanced black-hole model, used in some Box3/uhr runs, separates hot and cold gas accretion and yields faster BH growth and earlier quenching at high redshift (Dolag et al., 1 Apr 2025).

Haloes and galaxies are identified with FoF and SUBFIND, and merger trees are constructed with L-BaseTree in studies that require explicit progenitor tracking (Stoiber et al., 29 Sep 2025). This common infrastructure makes it possible to move between halo-scale thermodynamics, galaxy-scale kinematics, and stellar-halo archaeology within a single simulation family.

3. Calibration strategy, scaling relations, and validation

The most explicit statement of Magneticum’s calibration philosophy appears in the 2025 overview: the suite is tuned to the hot gas content of galaxy clusters rather than to the galaxy stellar mass function (Dolag et al., 1 Apr 2025). The same paper then evaluates 28 scaling relations from $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$5 to $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$6, including the halo-to-stellar-mass relation, the Kennicutt–Schmidt relation, the cosmic star formation rate density, the Fundamental Plane, the mass–size relation, the mass–metallicity relation, the Magorrian relation, and the temperature–mass relation (Dolag et al., 1 Apr 2025).

Several of the reported successes are unusually broad in scope. The suite is stated to match “a remarkable number of the observed scaling relations from $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$7 to $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$8,” including “the number density of quiescent galaxies at cosmic dawn, the mass--size evolution, the mass--metallicity relation, the Magorrian relation, and the temperature--mass relation” (Dolag et al., 1 Apr 2025). In the same synthesis, the cosmic star formation rate density peaks at $$m_{\rm DM} = 1.3\times 10^{10}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 2.6\times 10^{9}\,h^{-1}M_\odot,$$9–3 in uhr boxes and at $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$0 in hr boxes, while the advanced BH model in Box3/uhr produces massive quenched galaxies at $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$1–5 with number densities consistent with the cited JWST-era measurements (Dolag et al., 1 Apr 2025).

Cluster thermodynamics and SZ observables are among the best quantified parts of the programme. Using $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$2 clusters with $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$3 out to $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$4, the pressure-profile study finds significant mass and redshift dependence in profile shape, and fits a GNFW model with

$\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$5

for the global sample (Gupta et al., 2016). The same analysis finds that thermal pressure at $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$6 accounts for only 80 percent of the pressure required to maintain hydrostatic equilibrium, implying that even idealized hydrostatic mass estimates are biased at the 20 percent level (Gupta et al., 2016). For spherical $\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$7 the quoted intrinsic scatter is

$\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$8

whereas full light-cone measurements yield

$\epsilon_{\rm DM/gas} = 10~h^{-1}{\rm kpc}$9

because of line-of-sight structure (Gupta et al., 2016).

The large-volume SZ programme extends these cluster results to sky statistics. From a deep $\epsilon_* = 5~h^{-1}{\rm kpc}$0 light-cone out to $\epsilon_* = 5~h^{-1}{\rm kpc}$1, the thermal SZ one-point PDF has a high-$\epsilon_* = 5~h^{-1}{\rm kpc}$2 tail following a power law with index $\epsilon_* = 5~h^{-1}{\rm kpc}$3, and the mean fluctuating Compton-$\epsilon_* = 5~h^{-1}{\rm kpc}$4 is

$\epsilon_* = 5~h^{-1}{\rm kpc}$5

for the native cosmology, or

$\epsilon_* = 5~h^{-1}{\rm kpc}$6

after rescaling to the Planck 2015 cosmology (Dolag et al., 2015). The same study states that nearly half of this mean signal, about $\epsilon_* = 5~h^{-1}{\rm kpc}$7, comes from halos below a virial mass of $\epsilon_* = 5~h^{-1}{\rm kpc}$8 (Dolag et al., 2015). This SZ work is methodologically consistent with the hot-gas tuning strategy and is one reason the suite occupies a distinctive position relative to stellar-mass-function-tuned programmes.

4. Galaxy clusters, the cosmic web, and dynamical state

Magneticum has been used not only for statistical scaling relations but also for detailed analog studies of complex cluster systems. In the A3391/95 case study, an analogue is extracted from the $\epsilon_* = 5~h^{-1}{\rm kpc}$9 Box2/hr volume at $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$0. The selected pair has

$$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$1

with a 3D separation of $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$2 and projected separations of $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$3, $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$4, and $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$5 in the three principal projections (Biffi et al., 2021). The two clusters have overlapping $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$6 spheres of influence but disjoint virial radii, and the interconnecting bridge is found to be diffuse WHIM-like gas with typical temperature $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$7 keV, overdensity $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$8, and iron abundance $$m_{\rm DM} = 6.9\times 10^{8}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 1.4\times 10^{8}\,h^{-1}M_\odot,$$9, while 90–95 percent of the present-day bridge gas has never been inside $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$0 of any progenitor of the two main clusters (Biffi et al., 2021). The published interpretation is therefore explicitly pre-merger and filamentary rather than one of tidally stripped cluster atmospheres.

A different cluster-scale application concerns the relation between projected substructure and recent assembly. In the Abell 2744 study, the authors use Box2b/hr and a projection-based mass measurement to mimic lensing-derived substructure masses. They identify a cluster projection with eight substructures whose mass fractions,

$\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$1

are strikingly similar to the Abell 2744 benchmark, and they show that projected substructure masses are generally 2–3 times larger than the corresponding bound SUBFIND masses (Kimmig et al., 2022). The same work argues that both the total projected substructure mass fraction and the mass fraction of the eighth substructure are excellent tracers of recent dynamical assembly, with high fractions indicating merger activity within the last 2 Gyr (Kimmig et al., 2022).

These two applications illustrate a broader pattern in Magneticum usage. Cluster pairs, bridges, infalling groups, strong shock morphologies, projected substructure overdensities, and large-scale gas filaments are all treated as outcomes of the same cosmological hydrodynamical framework, rather than as isolated zoomed phenomena. The combination of large volumes and explicit baryonic physics is therefore not incidental; it is the condition under which these systems can be interpreted in terms of assembly history rather than only morphology.

5. Galaxy evolution, stellar populations, and low-surface-brightness structure

A substantial fraction of Magneticum’s scientific output concerns galaxies in dense environments and the coupling between star formation, AGN activity, and structure. In box2b/hr, the cluster-environment study selects galaxies with $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$2 in halos with $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$3 at $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$4 and $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$5. It finds that low-mass galaxies show monotonic declines of both star-forming ratio and AGN fraction toward the cluster center, whereas massive galaxies show a non-monotonic response: the star-forming ratio peaks between $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$6 and $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$7, while the AGN fraction reaches a minimum between $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$8 and $\epsilon_{\rm DM/gas} = 3.75~h^{-1}{\rm kpc}$9 and then rises rapidly for $\epsilon_* = 2~h^{-1}{\rm kpc}$0, with an additional AGN excess around $\epsilon_* = 2~h^{-1}{\rm kpc}$1 that persists even in isolated regions (Rihtaršič et al., 2023). This result is used there to argue that AGN fueling and star formation are not synchronized in massive cluster galaxies.

The post-starburst analysis extends this environmental program to quenching channels. In Box2, 647 PSBs are identified at $\epsilon_* = 2~h^{-1}{\rm kpc}$2 with $\epsilon_* = 2~h^{-1}{\rm kpc}$3 and tracked over 3.6 Gyr. Of the galaxies with merger trees extending back 2.5 Gyr, 88.9 percent experienced at least one merger and 64.7 percent at least one major merger; 23 percent of the $\epsilon_* = 2~h^{-1}{\rm kpc}$4 PSBs were rejuvenated during their starburst (Lotz et al., 2020). The paper further states that field PSBs are generally shut down via a strong increase in AGN feedback, with

$\epsilon_* = 2~h^{-1}{\rm kpc}$5

whereas cluster PSBs at $\epsilon_* = 2~h^{-1}{\rm kpc}$6 are predominantly infalling and show no signs of enhanced AGN activity, supporting ram-pressure stripping as the dominant environmental quenching channel (Lotz et al., 2020).

On smaller halo scales, the suite has been used to study anisotropic satellite systems. In Box4(uhr), the “Momentum in Thinnest Plane” method finds that thin planes of satellites with thickness $\epsilon_* = 2~h^{-1}{\rm kpc}$7 containing at least 50 percent of the satellites can be found in almost all systems, and that in Milky Way-mass-like hosts around 86 percent of such planes have at least 90 percent of the total satellite momentum aligned within the plane (Förster et al., 2022). The same study reports no correlation between the existence of a plane and central-galaxy morphology, but a clear preference for the minor axes of the satellite plane and the host galaxy to be aligned (Förster et al., 2022).

The stellar-halo programme uses the same Box4(uhr) for shells and streams. In LSST-like mock $\epsilon_* = 2~h^{-1}{\rm kpc}$8-band images with limiting surface brightness

$\epsilon_* = 2~h^{-1}{\rm kpc}$9

shells have a mean radius peaking at $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$0 and a median width $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$1, while streams have median radius $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$2 and median width $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$3 (Stoiber et al., 29 Sep 2025). The paper finds that both shells and streams are associated with localized depressions in stellar velocity dispersion, that shells are commonly produced by radial major mergers but also by minor mergers, that streams usually form from minor mergers on circular orbits, and that the visible shell or stream mass corresponds on average to approximately 20 percent of the progenitor mass (Stoiber et al., 29 Sep 2025). It also introduces a class of star-forming streams formed in situ from gas structures rather than from disrupted satellites (Stoiber et al., 29 Sep 2025).

Chemical enrichment studies provide a complementary perspective on the baryon cycle. The metals paper states that Magneticum reproduces the normalization and slope of the gas-phase mass–metallicity relation at both $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$4 and $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$5, reproduces stellar Fe gradients, and broadly matches ICM Fe abundances and multi-element abundance patterns, while also identifying too-steep gas-phase metallicity gradients and nearly flat stellar $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$6/Fe radial profiles as signatures of insufficient mixing or absent explicit metal diffusion (Dolag et al., 2017). This chemical programme is closely connected to the environmental, post-starburst, and stellar-halo applications, because all of them rely on the same integrated treatment of star formation, feedback, outflows, and stripping.

6. Methodological debates, limitations, data access, and distinct usage of the name

Magneticum’s published results are frequently framed against apparent tensions between observations and $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$7CDM. Two of the clearest cases are substructure masses in Abell 2744 and planes of satellites. In the Abell 2744 study, the claimed tension is explicitly traced to a methodological mismatch between observationally inferred projected masses and 3D bound subhalo masses from SUBFIND, with the projection-based estimator yielding masses typically 2–3 times larger (Kimmig et al., 2022). In the satellite-plane study, the authors argue that thin, kinematically coherent planes are common in a full hydrodynamical $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$8CDM simulation, and that the Local Group “planes of satellites” problem is therefore strongly sensitive to plane-finding method, baryonic physics, and selection effects (Förster et al., 2022).

The suite’s own synthesis also emphasizes unresolved issues. The 2025 overview notes over-prediction of the stellar mass function at $$m_{\rm DM} = 3.6\times 10^{7}\,h^{-1}M_\odot,\quad m_{\rm gas}^{\rm init} = 7.3\times 10^{6}\,h^{-1}M_\odot,$$9, somewhat high BCG+ICL stellar masses when very large apertures are used, and central stellar velocity dispersions that are generally lower than in IFU surveys (Dolag et al., 1 Apr 2025). The metals study separately identifies too-steep gas metallicity gradients, a shallower stellar mass–metallicity relation than observed, and flat stellar $\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$0/Fe profiles as limitations attributable to insufficient mixing, lack of explicit metal diffusion, resolution, and uncertainties in stellar yields and SNIa delay-time modeling (Dolag et al., 2017). The shells-and-streams analysis adds that sub-kpc features are beyond the nominal reach of the $\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$1 stellar softening in Box4(uhr), and that low-surface-brightness feature selection remains partly visual (Stoiber et al., 29 Sep 2025).

These limitations coexist with unusually rich public-facing infrastructure. The 2025 overview states that a subset of Magneticum data products is accessible through the Cosmosim web portal at https://c2papcosmosim.uc.lrz.de/, including interactive visualization, on-demand X-ray mocks via PHOX, map-making via SMAC, and SimCut extraction tools; additional material is available via www.magneticum.org/Data (Dolag et al., 1 Apr 2025). Earlier project papers also refer to a public web portal for cluster catalogues and derived products (Kimmig et al., 2022, Lotz et al., 2020).

A final terminological point is necessary because the name has acquired a second, unrelated usage in the LISA Pathfinder literature. Two 2024 papers use “Magneticum Pathfinder” informally to describe how LISA Pathfinder functioned as a magnetic pathfinder for future space-based gravitational-wave missions: one provides the first complete estimate of magnetic-induced acceleration noise in the February 2017 run, finding

$\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$2

at 1 mHz and

$\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$3

at 0.1 mHz, while the companion paper reports precision measurements of the test-mass magnetic parameters, including

$\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$4

and

$\epsilon_{\rm DM/gas} = 1.4~h^{-1}{\rm kpc}$5

in the low-frequency regime (Armano et al., 2024, Armano et al., 2024). In astrophysics, however, “Magneticum Pathfinder” overwhelmingly denotes the cosmological hydrodynamical simulation suite described above.