arXiv subjects

M. Angelinelli

Publications and source records attributed to M. Angelinelli.

9 recordsLinked to original sources

arXiv2024

Average X-ray properties of galaxy groups. From Milky Way-like halos to massive clusters

This study examines the average X-ray properties of massive halos at z< 0.2, covering the largest halo mass range to date, from Milky Way-like halos to massive clusters. The analysis is based on stacking in the eFEDS area of the GAMA galaxy group sample, validated with synthetic data that mimic observed eROSITA X-ray and GAMA optical data using Magneticum lightcones. Stacking was conducted in halo mass bins and tested for AGN and X-ray binary contamination, systematics in the halo mass proxy, and uncertainties in optical group centers. The study provides average X-ray surface brightness profiles in six mass bins, spanning Milky Way-like systems to poor clusters. The scatter in the X-ray luminosity-mass (LX-M) relation is attributed to gas concentration: low X-ray luminosity systems at fixed halo mass exhibit lower central gas concentrations than high-luminosity systems, consistent with Magneticum predictions. However, discrepancies in dark matter concentration arise, with Magneticum predicting undetected groups as older and more relaxed, while observations suggest the opposite. New LX-M relations are presented covering three decades of halo mass. These relations fit a single power law, aligning with previous studies. Magneticum matches observed gas distributions across all masses, whereas IllustrisTNG, EAGLE, Simba, and FLAMINGO exhibit significant discrepancies at various mass scales. Simulations calibrated on local galaxy properties accurately reproduce central galaxies but fail to capture gas properties. Conversely, simulations like Magneticum excel in gas predictions but produce overly massive central galaxies. Further exploration of gas and dark matter distributions and their effects on galaxy properties is critical to comprehending the role of gravitational forces and feedback in shaping large-scale structure and galaxy evolution.

astro-ph.GA↗

arXiv2024

The perils of stacking optically selected groups in eROSITA data. The Magneticum perspective

Hydrodynamical simulation predictions are often compared with observational data without fully accounting for systematics and biases specific to observational techniques. Using the magnetohydrodynamical simulation Magneticum, we generate mock eROSITA eRASS:4 data, combined with GAMA-like spectroscopic surveys and optically selected galaxy catalogs from the same light-cone, to analyze hot gas properties in galaxy groups via a stacking technique. This study aims to (i) incorporate observational systematics into predictions and (ii) evaluate the reliability of stacking techniques for determining average X-ray properties of galaxy groups. Our analysis provides X-ray emission predictions from Magneticum, including contributions from AGN, X-ray binaries (XRBs), and the Intra-Group Medium (IGM) as a function of halo mass, covering Milky Way (MW)-like groups to poor clusters. We find that AGN and XRBs dominate the X-ray surface brightness profiles of low-mass halos. The reliability of stacking techniques is tested by reproducing input X-ray surface brightness and electron density profiles, accounting for completeness and contamination of prior samples, miscentering of optical group centers, uncertainties in X-ray emissivity due to gas temperature and metallicity assumption, and systematics in halo mass proxies. The halo mass proxy emerges as the primary source of systematics, affecting X-ray surface brightness and scaling relations. We show that stacked X-ray luminosity-mass relations are flatter than input relations but consistent with observations. Additionally, the retrieved hot gas fraction-mass relation aligns well with observational data. These results highlight the need to account for systematic errors when comparing stacking techniques to other methods using different prior catalogs or predictions.

astro-ph.GA↗

arXiv2024

The hot gas mass fraction in halos. From Milky Way-like groups to massive clusters

By using eROSITA data in the eFEDS area, we provide a measure of the hot gas fraction vs. halo mass relation over the largest halo mass range, from Milky Way-sized halos to massive clusters, and to the largest radii ever probed so far in local systems. To cope with the incompleteness and selection biases of the X-ray selection, we apply the stacking technique in eROSITA data of a highly complete and tested sample of optically selected groups. The method has been extensively tested on mock observations. In massive clusters, the hot gas alone provides a baryon budget within $R_{200}$ consistent with the cosmic value. At the same time, at the group mass scale, it accounts only for 20-40% of it. The hot gas fraction vs. halo mass relation is well-fitted by a power law, with a consistent shape and a normalization varying at maximum by a factor of 2 from $r_{500}$ to $r_{200}$. Such a relation is consistent with other works in the literature that consider X-ray survey data at the same depth as eFEDS. However, it provides a lower average gas fraction in the group regime than works based on X-ray bright group samples. The comparison of the observed relation with the predictions of several hydrodynamical simulations (BAHAMAS, FLAMINGO, SIMBA, Illustris, IllustrisTNG, MillenniumTNG, and Magneticum) shows that all simulations but Magneticum and SIMBA overpredict the gas fraction, with the largest discrepancy (up to a factor of 3) in the massive group-poor cluster halo mass range. We emphasize the need for mechanisms that can effectively expel gas to larger radii in galaxy groups without excessively quenching star formation in their member galaxies. Current hydrodynamical simulations face a significant challenge in balancing their subgrid physics: none can sufficiently evacuate gas from the halo virial region without negatively impacting the properties of the resident galaxy population.

astro-ph.GA↗

arXiv2023

On the redshift evolution of the baryon and gas fraction in simulated groups and clusters of galaxies

We study the redshift evolution of the baryon budget in a large set of galaxy clusters from the {\it Magneticum} suite of SPH cosmological simulations. At high redshifts, we obtain "closed box" systems independently by the mass of the systems on radii greater than $3R_{500,\mathrm c}$, whereas at lower redshifts, only the most massive halos could be considered as `"closed box". The baryon fraction shows a general decrease with the redshift and, for less massive objects, we observe a much more prominent decrease than for massive halos. The gas depletion parameter $Y_{\rm gas}$ shows a steeper and highly scattered radial distribution in the central regions of less massive halos with respect to massive objects at all redshifts, while on larger radii the gas fraction distributions are independent of the masses or the redshifts. The hot component of the gas traces well the total amount of gas at low redshifts. At higher redshifts, the cold component provides a not negligible contribution to the total amount of baryon in our systems. Moreover, the behaviour of the baryonic, entire gas, and hot gas phase depletion parameters as a function of radius, mass, and redshift are described by some functional forms. The evolution of metallicity and stellar mass in halos suggests that the early enrichment process is dominant. We investigate correlations between the time evolution of AGN feedback and the depletion parameters. We demonstrate that the energy injected by the AGN activity shows a particularly strong positive correlation with $Y_{\rm bar}$, $Y_{\rm cold}$,$Y_{\rm star}$ and a negative one with $Y_{\rm hot}$, $Z_{\rm Tot}$. These trends are consistent with previous works, meaning that our results, combined with findings derived from current and future X-rays observations, represent possible proxies to test the AGN feedback models used in different suites of numerical simulations.

astro-ph.CO↗

arXiv2022

Mapping "out-of-the-box" the properties of the baryons in massive halos

We study the distributions of the baryons in massive halos ($M_{vir} > 10^{13} \ h^{-1}M_{\odot}$) in the $Magneticum$ suite of Smoothed Particle Hydrodynamical cosmological simulations, out to the unprecedented radial extent of $10 R_{500,\mathrm c}$. We confirm that, under the action of non-gravitational physical phenomena, the baryon mass fraction is lower in the inner regions ($ 6 R_{500,\mathrm c}$), where the baryon depletion factor $Y_{\rm bar} = f_{\rm bar} / (\Omega_{\rm b}/\Omega_{\rm m})$ approaches the value of unity, expected for "closed-box" systems. We find that both the radial and mass dependency of the baryon, gas, and hot depletion factors are predictable and follow a simple functional form. The star mass fraction is higher in less massive systems, decreases systematically with increasing radii, and reaches a constant value of $Y_{\rm star} \approx 0.09$, where also the gas metallicity is constant, regardless of the host halo mass, as a result of the early ($z>2$) enrichment process.

astro-ph.GA↗

arXiv2021

Properties of clumps and filaments around galaxy clusters

We report on the possibility of studying the proprieties of cosmic diffuse baryons by studying self-gravitating clumps and filaments connected to galaxy clusters. While filaments are challenging to detect with X-ray observations, the higher density of clumps makes them visible and a viable tracer to study the thermodynamical proprieties of baryons undergoing accretion along cosmic web filaments onto galaxy clusters. We developed new algorithms to identify these structures and applied them to a set of non-radiative cosmological simulations of galaxy clusters at high resolution. We find that in those simulated clusters, the density and temperature of clumps are independent of the mass of the cluster where they reside. We detected a positive correlation between the filament temperature and the host cluster mass. The density and temperature of clumps and filaments also tended to correlate. Both the temperature and density decrease moving outward. We observed that clumps are hotter, more massive, and more luminous if identified closer to the cluster center. Especially in the outermost cluster regions (~3*R500,c or beyond), X-ray observations might already have the potential to locate cosmic filaments based on the distribution of clumps and to allow one to study the thermodynamics of diffuse baryons before they are processed by the intracluster medium.

astro-ph.CO↗

arXiv2019

Turbulent pressure support and hydrostatic mass-bias in the intracluster medium

The degree of turbulent pressure support by residual gas motions in galaxy clusters is not well known. Mass modelling of combined X-ray and Sunyaev Zel'dovich observations provides an estimate of turbulent pressure support in the outer regions of several galaxy clusters. Here, we test two different filtering techniques to disentangle bulk from turbulent motions in non-radiative high-resolution cosmological simulations of galaxy clusters using the cosmological hydro code ENZO. We find that the radial behavior of the ratio of non-thermal pressure to total gas pressure as a function of cluster-centric distance can be described by a simple polynomial function. The typical non-thermal pressure support in the centre of clusters is $\sim$5%, increasing to $\sim$15% in the outskirts, in line with the pressure excess found in recent X-ray observations. While the complex dynamics of the ICM makes it impossible to reconstruct a simple correlation between turbulent motions and hydrostatic bias, we find that a relation between them can be established using the median properties of a sample of objects. Moreover, we estimate the contribution of radial accelerations to the non-thermal pressure support and conclude that it decreases moving outwards from 40% (in the core) to 15% (in the cluster's outskirts). Adding this contribution to one provided by turbulence, we show that it might account for the entire observed hydrostatic bias in the innermost regions of the clusters, and for less than 80% of it at $r > 0.8 r_{200, m}$.

astro-ph.CO↗

arXiv2019

Detecting shocked intergalactic gas with X-ray and radio observations

Detecting the thermal and non-thermal emission from the shocked cosmic gas surrounding large-scale structures represents a challenge for observations, as well as a unique window into the physics of the warm-hot intergalactic medium. In this work, we present synthetic radio and X-ray surveys of large cosmological simulations in order to assess the chances of jointly detecting the cosmic web in both frequency ranges. We then propose best observing strategies tailored for existing (LOFAR, MWA and XMM) or future instruments (SKA-LOW and SKA-MID, ATHENA and eROSITA). We find that the most promising targets are the extreme peripheries of galaxy clusters in an early merging stage, where the merger causes the fast compression of warm-hot gas onto the virial region. By taking advantage of a detection in the radio band, future deep X-ray observations will probe this gas in emission, and help us to study plasma conditions in the dynamic warm-hot intergalactic medium with unprecedented detail.

astro-ph.CO↗

arXiv2018

The turbulent pressure support in galaxy clusters revisited

Due to their late formation in cosmic history, clusters of galaxies are not fully in hydrostatic equilibrium and the gravitational pull of their mass at a given radius is expected not to be entirely balanced by the thermal gas pressure. Turbulence may supply additional pressure, and recent (X-ray and SZ) hydrostatic mass reconstructions claim a pressure support of $\sim 5-15\%$ of the total pressure at $R_{\rm 200}$. In this work we show that, after carefully disentangling bulk from small-scale turbulent motions in high-resolution simulations of galaxy clusters, we can constrain which fraction of the gas kinetic energy effectively provides pressure support in the cluster's gravitational potential. While the ubiquitous presence of radial inflows in the cluster can lead to significant bias in the estimate of the non-thermal pressure support, we report that only a part of this energy effectively acts as a source of pressure, providing a support of the order of $\sim 10\%$ of the total pressure at $R_{\rm 200}$.

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