arXiv subjects

Sara Santoni

Publications and source records attributed to Sara Santoni.

5 recordsLinked to original sources

arXiv2026

The Three Hundred project: Low Gas Fraction Galaxy Clusters properties and their environment

Galaxy cluster samples based on X-ray and Sunyaev-Zel'dovich (SZ) observations are affected by selection biases. These catalogs preferentially include systems with high gas content and surface brightness. Excluding objects with depleted gas content, low-gas-fraction clusters (LGFCs), could lead to an incomplete sampling. We aim to investigate the abundance and the properties of the LGFCs population using The Three Hundred hydrodynamical simulations, focusing on the Gadget-X code. In particular, we study outliers in the $f_{\mathrm{g},500} - M_{500}$ relation, environmental influences, and their behavior in key scaling relations, with a focus on the Compton-Y observable. We analyze a sample of $N_{\mathrm{tot}} = 9858$ simulated objects from The Three Hundred, in the redshift band $z \in [0;0.817]$. LGFCs are selected statistically as outliers of the $f_{\mathrm{g},500}-M_{500}$ relation. To analyze environmental effects, we compare the gas density and temperature radial profiles of LGFCs against the No-LGFCs population. Finally, we study how the temperature, entropy, and spherical Compton parameter scaling relations are affected by the inclusion of LGFCs. We find that LGFCs are preferentially found at the low-mass end and their abundance increases toward low redshift. Radial profiles of LGFCs show lower gas concentrations in the core regions and higher temperatures, suggesting a more diffuse and heated ICM. This behavior is also reflected in the entropy scaling relation, where LGFCs are extreme positive outliers. Contrary to observations, the $Y_{\mathrm{sph},500}$ values of LGFCs show no significant deviation from the general population. Nevertheless, we cannot rule out that these differences are partly driven by the mass incompleteness at the low-mass end and the environmental bias of our simulated sample.

astro-ph.GA↗

arXiv2026

Here, There and Everywhere: How AGN jets affect galaxy cluster environments

Active galactic nuclei (AGN) feedback via black hole-driven jets and winds plays a key role in redistributing matter across megaparsec scales. However, the implementation of jet feedback in cosmological simulations remains highly prescriptive, leading to uncertainties in the predicted state of the Warm-Hot Intergalactic Medium and other extragalactic observables. We investigate how variations in AGN jet velocity, orientation, and delayed hydrodynamic coupling impact the thermodynamic state of gas surrounding galaxy clusters. We aim to identify observational signatures in the thermal Sunyaev-Zel'dovich (tSZ) effect and galaxy properties that can constrain these models. We employ zoom-in hydrodynamic simulations centered on three galaxy clusters from The Three Hundred, utilizing the SIMBA-C model and various feedback parameters. We use filament-finding algorithms and oriented stacking to probe the effect on large-scale structure and compare our results to observational data for brightest cluster galaxies from eRASS1, black hole-halo mass relations and baryonic mass fractions. Jet velocity is the dominant tested parameter in heating low-density environments at $z > 1$. At lower-$z$, higher velocity jets quench star formation, expel baryonic matter, and prevent black hole growth. While the tSZ signal within the central cluster and surrounding filaments is only affected by $\sim10\%$, the signal in under-dense regions outside filaments is enhanced by $\sim100\%$. In this case study, high velocity AGN jets provide the best match to galaxy properties from eRASS1 and other X-ray surveys. We find that hot gas in low-density regimes is a sensitive probe of AGN feedback. Future high-resolution tSZ surveys like the Simons Observatory and spectral-distortion experiments like FOSSIL have the potential to probe the thermal state of the gas outside clusters to distinguish between these feedback models.

astro-ph.CO↗

arXiv2026

The Three Hundred project: cosmic web identification from 2D gas and Compton-$y$ maps of galaxy clusters outskirts

Galaxy clusters are located at the nodes of the filamentary network known as the cosmic web. A more comprehensive understanding of galaxy clusters can be achieved by considering their environment, in particular, the filamentary structures to which they are connected. In this work, we aim to assess the reliability of the cosmic web reconstruction from mock observational data. In particular, we aim to quantify the effects of the 2D projection relative to the underlying 3D network and the impact of using the Sunyaev-Zel'dovich (SZ) effect as a tracer of the cosmic web. We reconstruct the filamentary networks in the outskirts of The Three Hundred simulated clusters with the filament finder DisPerSE. First, we extract the networks from the 2D gas distribution and evaluate their purity and completeness with respect to the 3D networks projected along the line of sight. We also compute the distances between the corresponding skeletons. Moreover, we identify filaments from simulated Compton-$y$ maps of the clusters at redshift $z=0$, and we compare them with the 2D gas network. The skeletons extracted from 2D maps provide good representations of the underlying 3D ones, both in terms of critical points and filaments. We find a median distance between the spines of the 2D and projected 3D networks of approximately $0.22 \, h^{-1}$ Mpc, although the connectivity derived from the 2D networks is slightly underestimated. We observe a good spatial agreement between the gas and SZ networks, with a median distance of $\approx 0.24 \, h^{-1}$ Mpc. Finally, we show that gas outside galaxy clusters is preferentially located in filamentary structures, which contribute $\sim 80\%$ of the integrated Compton-$Y$ parameter of clusters' outskirts.

astro-ph.CO↗

arXiv2024

The Three Hundred project: Estimating the dependence of gas filaments on the mass of galaxy clusters

Galaxy clusters are located in the densest areas of the universe and are intricately connected to larger structures through the filamentary network of the Cosmic Web. In this scenario, matter flows from areas of lower density to higher density. As a result, the properties of galaxy clusters are deeply influenced by the filaments that are attached to them, which are quantified by a parameter known as connectivity. We explore the dependence of gas-traced filaments connected to galaxy clusters on the mass and dynamical state of the cluster. Moreover, we evaluate the effectiveness of the cosmic web extraction procedure from the gas density maps of simulated cluster regions. Using the DisPerSE cosmic web finder, we identify filamentary structures from 3D gas particle distribution in 324 simulated regions of $30 \, h^{-1}$ Mpc side from The Three Hundred hydrodynamical simulation at redshifts z=0, 1, and 2. We estimate the connectivity at various apertures for $\sim3000$ groups and clusters spanning a mass range from $10^{13} \, h^{-1} \, M_{\odot}$ to $10^{15} \, h^{-1} \, M_{\odot}$. Relationships between connectivity and cluster properties like radius, mass, dynamical state and hydrostatic mass bias are explored. We show that the connectivity is strongly correlated with the mass of galaxy clusters, with more massive clusters being on average more connected. This finding aligns with previous studies in literature, both from observational and simulated data sets. Additionally, we observe a dependence of the connectivity on the aperture at which it is estimated. We find that connectivity decreases with cosmic time, while no dependencies on the dynamical state and hydrostatic mass bias of the cluster are found. Lastly, we observe a significant agreement between the connectivity measured from gas-traced and mock-galaxies-traced filaments in the simulation.

astro-ph.CO↗

arXiv2023

Impact of filaments on galaxy cluster properties in The Three Hundred simulation

Galaxy clusters and their filamentary outskirts reveal useful laboratories to test cosmological models and investigate Universe composition and evolution. Their environment, in particular the filaments of the Cosmic Web to which they are connected, plays an important role in shaping the properties of galaxy clusters. In this project, we analyse the gas filamentary structures present in 324 regions of The Three Hundred hydrodynamical simulation extracted with the DisPerSE filament finder. We estimate the number of gas filaments globally connected to several galaxy clusters, i.e. the connectivity k, with a mass range of $10^{13} \leq M_{200} \, h^{-1} \, M_{\odot} \leq 10^{15} $ at redshift $z=0$. We study the positive correlation between the connectivity and mass of galaxy clusters. Moreover, we explore the impact of filaments on the dynamical state of clusters, quantified by the degree of relaxation parameter $χ$.

astro-ph.CO↗