arXiv subjects

M. Roncarelli

Publications and source records attributed to M. Roncarelli.

At least 55 records · Page 3Linked to original sources

arXiv2018

Non-thermal pressure support in X-COP galaxy clusters

Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions). Measuring the level of non-thermal pressure support is necessary to understand the processes leading to the virialization of the gas within the potential well of the main halo and to calibrate the biases in hydrostatic mass estimates. We present high-quality measurements of hydrostatic masses and intracluster gas fraction out to the virial radius for a sample of 12 nearby clusters with available XMM-Newton and Planck data. We compare our hydrostatic gas fractions with the expected universal gas fraction to constrain the level of non-thermal pressure support. We find that hydrostatic masses require little correction and infer a median non-thermal pressure fraction of $\sim6\%$ and $\sim10\%$ at $R_{500}$ and $R_{200}$, respectively. Our values are lower than the expectations of hydrodynamical simulations, possibly implying a faster thermalization of the gas. If instead we use the mass calibration adopted by the Planck team, we find that the gas fraction of massive local systems implies a mass bias $1-b=0.85\pm0.05$ for SZ-derived masses, with some evidence for a mass-dependent bias. Conversely, the high bias required to match Planck CMB and cluster count cosmology is excluded by the data at high significance, unless the most massive halos are missing a substantial fraction of their baryons.

astro-ph.CO↗

arXiv2018

Athena X-IFU synthetic observations of galaxy clusters to probe the chemical enrichment of the Universe

Answers to the metal production of the Universe can be found in galaxy clusters, notably within their Intra-Cluster Medium (ICM). The X-ray Integral Field Unit (X-IFU) on board the next-generation European X-ray observatory Athena (2030s) will provide the necessary leap forward in spatially-resolved spectroscopy required to disentangle the intricate mechanisms responsible for this chemical enrichment. In this paper, we investigate the future capabilities of the X-IFU in probing the hot gas within galaxy clusters. From a test sample of four clusters extracted from cosmological hydrodynamical simulations, we present comprehensive synthetic observations of these clusters at different redshifts (up to z = 2) and within the scaled radius R500 performed using the instrument simulator SIXTE. Through 100 ks exposures, we demonstrate that the X-IFU will provide spatially-resolved mapping of the ICM physical properties with little to no biases (<5%) and well within statistical uncertainties. The detailed study of abundance profiles and abundance ratios within R500 also highlights the power of the X-IFU in providing constraints on the various enrichment models. From synthetic observations out to z = 2, we also quantify its ability to track the chemical elements across cosmic time with excellent accuracy, and thereby to investigate the evolution of metal production mechanisms as well as the link to the stellar initial mass-function. Our study demonstrates the unprecedented capabilities of the X-IFU in unveiling the properties of the ICM but also stresses the data analysis challenges faced by future high-resolution X-ray missions such as Athena.

astro-ph.CO↗

arXiv2018

Measuring turbulence and gas motions in galaxy clusters via synthetic Athena X-IFU observations

The X-ray Integral Field Unit (X-IFU) that will be on board the Athena telescope will provide an unprecedented view of the intracluster medium (ICM) kinematics through the observation of gas velocity, $v$, and velocity dispersion, $w$, via centroid-shift and broadening of emission lines, respectively. The improvement of data quality and quantity requires an assessment of the systematics associated with this new data analysis, namely biases, statistical and systematic errors, and possible correlations between the different measured quantities. We have developed an end-to-end X-IFU simulator that mimics a full X-ray spectral fitting analysis on a set of mock event lists, obtained using SIXTE. We have applied it to three hydrodynamical simulations of a Coma-like cluster that include the injection of turbulence. This allowed us to assess the ability of X-IFU to map five physical quantities in the cluster core: emission measure, temperature, metal abundance, velocity and velocity dispersion. Finally, starting from our measurements maps, we computed the 2D structure function (SF) of emission measure fluctuations, $v$ and $w$ and compared them with those derived directly from the simulations. All quantities match with the input projected values without bias; the systematic errors were below 5%, except for velocity dispersion whose error reaches about 15%. Moreover, all measurements prove to be statistically independent, indicating the robustness of the fitting method. Most importantly, we recover the slope of the SFs in the inertial regime with excellent accuracy, but we observe a systematic excess in the normalization of both SF$_v$ and SF$_w$ ascribed to the simplistic assumption of uniform and (bi-)Gaussian measurement errors. Our work highlights the excellent capabilities of Athena X-IFU in probing the thermodynamic and kinematic properties of the ICM. (abridged)

astro-ph.CO↗

arXiv2018

The kinematic Sunyaev-Zel'dovich effect of the large-scale structure (II): the effect of modified gravity

The key to understand the nature of dark energy relies in our ability to probe the distant Universe. In this framework, the recent detection of the kinematic Sunyaev-Zel'dovich (kSZ) effect signature in the cosmic microwave background obtained with the South Pole Telescope (SPT) is extremely useful since this observable is sensitive to the high-redshift diffuse plasma. We analyse a set of cosmological hydrodynamical simulation with 4 different realisations of a Hu & Sawicki $f(R)$ gravity model, parametrised by the values of $\overline{f}_{\rm R,0}=(0,-10^{-6},-10^{-5},-10^{-4})$, to compute the properties of the kSZ effect due to the ionized Universe and how they depend on $\overline{f}_{\rm R,0}$ and on the redshift of reionization, $z_{\rm re}$. In the standard General Relativity limit ($\overline{f}_{\rm R,0}$=0) we obtain an amplitude of the kSZ power spectrum of $\mathcal{D}^{\rm kSZ}_{3000}=4.1\,$$μ$K$^2$ ($z_{\rm re}$=8.8), close to the $+1σ$ limit of the $\mathcal{D}^{\rm kSZ}_{3000}=(2.9\pm1.3)\,$$μ$K$^2$ measurement by SPT. This corresponds to an upper limit on the kSZ contribute from patchy reionization of $\mathcal{D}^{\rm kSZ,patchy}_{3000}<0.9\,$$μ$K$^2$ (95 per cent confidence level). Modified gravity boosts the kSZ signal by about 3, 12 and 50 per cent for $\overline{f}_{\rm R,0}=(-10^{-6},-10^{-5},-10^{-4})$, respectively, with almost no dependence on the angular scale. This means that with modified gravity the limits on patchy reionization shrink significantly: for $\overline{f}_{\rm R,0}=-10^{-5}$ we obtain $\mathcal{D}^{\rm kSZ,patchy}_{3000}<0.4\,$$μ$K$^2$. Finally, we provide an analytical formula for the scaling of the kSZ power spectrum with $z_{\rm re}$ and $\overline{f}_{\rm R,0}$ at different multipoles: at $\ell=3000$ we obtain $\mathcal{D}^{\rm kSZ}_{3000}\propto z_{\rm re}^{0.24}\left(1+\sqrt{\left|\overline{f}_{\rm R,0}\right|}\right)^{41}$.

astro-ph.CO↗

arXiv2017

Searching for galaxy clusters in the Kilo-Degree Survey

In this paper, we present the tools used to search for galaxy clusters in the Kilo Degree Survey (KiDS), and our first results. The cluster detection is based on an implementation of the optimal filtering technique that enables us to identify clusters as over-densities in the distribution of galaxies using their positions on the sky, magnitudes, and photometric redshifts. The contamination and completeness of the cluster catalog are derived using mock catalogs based on the data themselves. The optimal signal to noise threshold for the cluster detection is obtained by randomizing the galaxy positions and selecting the value that produces a contamination of less than 20%. Starting from a subset of clusters detected with high significance at low redshifts, we shift them to higher redshifts to estimate the completeness as a function of redshift: the average completeness is ~ 85%. An estimate of the mass of the clusters is derived using the richness as a proxy. We obtained 1858 candidate clusters with redshift 0 < z_c < 0.7 and mass 13.5 < log(M500/Msun) < 15 in an area of 114 sq. degrees (KiDS ESO-DR2). A comparison with publicly available Sloan Digital Sky Survey (SDSS)-based cluster catalogs shows that we match more than 50% of the clusters (77% in the case of the redMaPPer catalog). We also cross-matched our cluster catalog with the Abell clusters, and clusters found by XMM and in the Planck-SZ survey; however, only a small number of them lie inside the KiDS area currently available.

astro-ph.CO↗

arXiv2016

The XMM Cluster Outskirts Project (X-COP): Physical conditions to the virial radius of Abell 2142

Context. Galaxy clusters are continuously growing through the accretion of matter in their outskirts. This process induces inhomogeneities in the gas density distribution (clumping) which need to be taken into account to recover the physical properties of the intracluster medium (ICM) at large radii. Aims. We studied the thermodynamic properties in the outskirts (R > R500) of the massive galaxy cluster Abell 2142 by combining the Sunyaev Zel'dovich (SZ) effect with the X-ray signal. Methods. We combined the SZ pressure profile measured by Planck with the XMM-Newton gas density profile to recover radial profiles of temperature, entropy and hydrostatic mass out to 2R500. We used a method that is insensitive to clumping to recover the gas density, and we compared the results with traditional X-ray measurement techniques. Results. When taking clumping into account, our joint SZ/X-ray entropy profile is consistent with the predictions from pure gravitational collapse, whereas a significant entropy flattening is found when the effect of clumping is neglected. The hydrostatic mass profile recovered using joint X-ray/SZ data agrees with that obtained from spectroscopic X-ray measurements and with mass reconstructions obtained through weak lensing and galaxy kinematics. Conclusions. We found that clumping can explain the entropy flattening observed by Suzaku in the outskirts of several clusters. When using a method insensitive to clumping for the reconstruction of the gas density, the thermodynamic properties of Abell 2142 are compatible with the assumption that the thermal gas pressure sustains gravity and that the entropy is injected at accretion shocks, with no need to evoke more exotic physics. Our results highlight the need for X-ray observations with sufficient spatial resolution, and large collecting area, to understand the processes at work in cluster outer regions.

astro-ph.CO↗

arXiv2015

The gas distribution in the outer regions of galaxy clusters

We present the analysis of a local (z = 0.04 - 0.2) sample of 31 galaxy clusters with the aim of measuring the density of the X-ray emitting gas in cluster outskirts. We compare our results with numerical simulations to set constraints on the azimuthal symmetry and gas clumping in the outer regions of galaxy clusters. We exploit the large field-of-view and low instrumental background of ROSAT/PSPC to trace the density of the intracluster gas out to the virial radius. We perform a stacking of the density profiles to detect a signal beyond r200 and measure the typical density and scatter in cluster outskirts. We also compute the azimuthal scatter of the profiles with respect to the mean value to look for deviations from spherical symmetry. Finally, we compare our average density and scatter profiles with the results of numerical simulations. As opposed to some recent Suzaku results, and confirming previous evidence from ROSAT and Chandra, we observe a steepening of the density profiles beyond \sim r500. Comparing our density profiles with simulations, we find that non-radiative runs predict too steep density profiles, whereas runs including additional physics and/or treating gas clumping are in better agreement with the observed gas distribution. We report for the first time the high-confidence detection of a systematic difference between cool-core and non-cool core clusters beyond \sim 0.3r200, which we explain by a different distribution of the gas in the two classes. Beyond \sim r500, galaxy clusters deviate significantly from spherical symmetry, with only little differences between relaxed and disturbed systems. We find good agreement between the observed and predicted scatter profiles, but only when the 1% densest clumps are filtered out in the simulations. [Abridged]

astro-ph.CO↗

arXiv2015

Missing baryons traced by the galaxy luminosity density in the large-scale WHIM filaments

We propose a new approach to the missing baryons problem. Building on the common assumption that the missing baryons are in the form of the Warm Hot Intergalactic Medium (WHIM), we further assumed here that the galaxy luminosity density can be used as a tracer of the WHIM. The latter assumption is supported by our finding of a significant correlation between the WHIM density and the galaxy luminosity density in the hydrodynamical simulations of Cui et al. (2012). We further found that the fraction of the gas mass in the WHIM phase is substantially (by a factor of $\sim$1.6) higher within the large scale galactic filaments, i.e. $\sim$70\%, compared to the average in the full simulation volume of $\sim$0.1\,Gpc$^3$. The relation between the WHIM overdensity and the galaxy luminosity overdensity within the galactic filaments is consistent with linear: $δ_{\rm whim}\,=\,0.7\,\pm\,0.1\,\times\,δ_\mathrm{LD}^{0.9 \pm 0.2}$. We applied our procedure to the line of sight to the blazar H2356-309 and found evidence for the WHIM in correspondence of the Sculptor Wall (z $\sim$0.03 and $\log{N_H}$ = $19.9^{+0.1}_{-0.3}$) and Pisces-Cetus superclusters (z $\sim$0.06 and $\log{N_H}$ = $19.7^{+0.2}_{-0.3}$), in agreement with the redshifts and column densities of the X-ray absorbers identified and studied by Fang et al. (2010) and Zappacosta et al. (2010). This agreement indicates that the galaxy luminosity density and galactic filaments are reliable signposts for the WHIM and that our method is robust in estimating the WHIM density. The signal that we detected cannot originate from the halos of the nearby galaxies since they cannot account for the large WHIM column densities that our method and X-ray analysis consistently find in the Sculptor Wall and Pisces-Cetus superclusters.

astro-ph.CO↗

arXiv2014

Gas clumping in galaxy clusters

The reconstruction of galaxy cluster's gas density profiles is usually performed by assuming spherical symmetry and averaging the observed X-ray emission in circular annuli. In the case of a very inhomogeneous and asymmetric gas distribution, this method has been shown to return biased results in numerical simulations because of the $n^2$ dependence of the X-ray emissivity. We propose a method to recover the true density profiles in the presence of inhomogeneities, based on the derivation of the azimuthal median of the surface brightness in concentric annuli. We demonstrate the performance of this method with numerical simulations, and apply it to a sample of 31 galaxy clusters in the redshift range 0.04-0.2 observed with ROSAT/PSPC. The clumping factors recovered by comparing the mean and the median are mild and show a slight trend of increasing bias with radius. For $R<R_{500}$, we measure a clumping factor $\sqrt{C}<1.1$, which indicates that the thermodynamic properties and hydrostatic masses measured in this radial range are only mildly affected by this effect. Comparing our results with three sets of hydrodynamical numerical simulations, we found that non-radiative simulations significantly overestimate the level of inhomogeneities in the ICM, while the runs including cooling, star formation, and AGN feedback reproduce the observed trends closely. Our results indicate that most of the accretion of X-ray emitting gas is taking place in the diffuse, large-scale accretion patterns rather than in compact structures.

astro-ph.CO↗

arXiv2014

Finding and characterising WHIM structures using the luminosity density method

We have developed a new method to approach the missing baryons problem. We assume that the missing baryons reside in a form of Warm Hot Intergalactic Medium, i.e. the WHIM. Our method consists of (a) detecting the coherent large scale structure in the spatial distribution of galaxies that traces the Cosmic Web and that in hydrodynamical simulations is associated to the WHIM, (b) map its luminosity into a galaxy luminosity density field, (c) use numerical simulations to relate the luminosity density to the density of the WHIM, (d) apply this relation to real data to trace the WHIM using the observed galaxy luminosities in the Sloan Digital Sky Survey and 2dF redshift surveys. In our application we find evidence for the WHIM along the line of sight to the Sculptor Wall, at redshifts consistent with the recently reported X-ray absorption line detections. Our indirect WHIM detection technique complements the standard method based on the detection of characteristic X-ray absorption lines, showing that the galaxy luminosity density is a reliable signpost for the WHIM. For this reason, our method could be applied to current galaxy surveys to optimise the observational strategies for detecting and studying the WHIM and its properties. Our estimates of the WHIM hydrogen column density in Sculptor agree with those obtained via the X-ray analysis. Due to the additional column density estimate, our method has potential for improving the constrains of the physical parameters of the WHIM as derived with X-ray absorption, and thus for improving the understanding of the missing baryons problem.

astro-ph.CO↗

arXiv2013

The Hot and Energetic Universe: The astrophysics of galaxy groups and clusters

As the nodes of the cosmic web, clusters of galaxies trace the large-scale distribution of matter in the Universe. They are thus privileged sites in which to investigate the complex physics of structure formation. However, the complete story of how these structures grow, and how they dissipate the gravitational and non-thermal components of their energy budget over cosmic time, is still beyond our grasp. Fundamental questions such as How do hot diffuse baryons accrete and dynamically evolve in dark matter potentials? How and when was the energy that we observe in the ICM generated and distributed? Where and when are heavy elements produced and how are they circulated? are still unanswered. Most of the cluster baryons exists in the form of a diffuse, hot, metal-enriched plasma that radiates primarily in the X-ray band (the intracluster medium, ICM), allowing the X-ray observations of the evolving cluster population to provide a unique opportunity to address these topics. Athena+ with its large collecting area and unprecedented combination of high spectral and angular resolution offers the only way to make major advances in answering these questions. Athena+ will show how the baryonic gas evolves in the dark matter potential wells by studying the motions and turbulence in the ICM. Athena+ will be able to resolve the accreting region both spatially and spectroscopically, probing the true nature and physical state of the X-ray emitting plasma. Athena+ has the capabilities to permit a definitive understanding of the formation and evolution of large-scale cosmic structure through the study of the cluster population.

astro-ph.HE↗

arXiv2013

Large-scale inhomogeneities of the intracluster medium: improving mass estimates using the observed azimuthal scatter

Using a set of hydrodynamical simulations of 62 galaxy clusters and groups we study the ICM of inhomogeneities, focusing on the ones on the large scale that, unlike clumps, are the most difficult to identify. To this purpose we introduce the concept of residual clumpiness, C_R, that quantifies the large-scale inhomogeneity of the ICM. After showing that this quantity can be robustly defined for relaxed systems, we characterize how it varies with radius, mass and dynamical state of the halo. Most importantly, we observe that it introduces an overestimate in the determination of the density profile from the X-ray emission, which translates into a systematic overestimate of 6 (12)% in the measurement of M_gas at R_200 for our relaxed (perturbed) cluster sample. At the same time, the increase of C_R with radius introduces also a ~2% systematic underestimate in the measurement of the hydrostatic-equilibrium mass (M_he), which adds to the previous one generating a systematic ~8.5% overestimate in f_gas in our relaxed sample. Since the residual clumpiness of the ICM is not directly observable, we study its correlation with the azimuthal scatter in the X-ray surface brightness of the halo and in the y-parameter profiles. We find that their correlation is highly significant (r_S = 0.6-0.7), allowing to define the azimuthal scatter measured in the X-ray surface brightness profile and in the y-parameter as robust proxies of C_R. After providing a function that connects the two quantities, we obtain that correcting the observed gas density profiles using the azimuthal scatter eliminates the bias in the measurement of M_gas for relaxed objects, which becomes (0+/-2)% up to 2R_200, and reduces it by a factor of 3 for perturbed ones. This method allows also to eliminate the systematics on the measurements of M_he and f_gas, although a significant halo to halo scatter remains. (abridged)

astro-ph.CO↗

arXiv2012

The nature of the unresolved extragalactic soft CXB

In this paper we investigate the power spectrum of the unresolved 0.5-2 keV CXB with deep Chandra 4 Ms observations in the CDFS. We measured a signal which, on scales >30", is significantly higher than the Shot-Noise and is increasing with the angular scale. We interpreted this signal as the joint contribution of clustered undetected sources like AGN, Galaxies and Inter-Galactic-Medium (IGM). The power of unresolved cosmic sources fluctuations accounts for \sim 12% of the 0.5-2 keV extragalactic CXB. Overall, our modeling predicts that \sim 20% of the unresolved CXB flux is made by low luminosity AGN, \sim 25% by galaxies and \sim 55% by the IGM (Inter Galactic Medium). We do not find any direct evidence of the so called Warm Hot Intergalactic Medium (i.e. matter with 10^5K 7.5 and compared it with SMBH evolution models.

astro-ph.CO↗

arXiv2012

The effect of feedback on the emission properties of the Warm-Hot Intergalactic Medium

At present, 30-40 per cent of the baryons in the local Universe is still undetected. According to theoretical predictions, this gas should reside in filaments filling the large-scale structure (LSS) in the form of a Warm-Hot Intergalactic Medium (WHIM), at temperatures of 10^5 - 10^7 K, thus emitting in the soft X-ray energies via free-free interaction and line emission from heavy elements. In this work we characterize the properties of the X-ray emission of the WHIM, and the LSS in general, focusing on the influence of different physical mechanisms, namely galactic winds (GWs), black-hole feedback and star-formation, and providing estimates of possible observational constraints. To this purpose we use a set of cosmological hydrodynamical simulations that include a self-consistent treatment of star-formation and chemical enrichment of the intergalactic medium, that allows us to follow the evolution of different metal species. We construct a set of simulated light-cones to make predictions of the emission in the 0.3-10 keV energy range. We obtain that GWs increase by a factor of 2 the emission of both galaxy clusters and WHIM. The amount of oxygen at average temperature and, consequently, the amount of expected bright Ovii and Oviii lines is increased by a factor of 3 due to GWs and by 20 per cent when assuming a top-heavy IMF. We compare our results with current observational constraints and find that the emission from faint groups and WHIM should account from half to all of the unresolved X-ray background in the 1-2 keV band.

astro-ph.CO↗

arXiv2010

The scatter in the radial profiles of X-ray luminous galaxy clusters as diagnostic of the thermodynamical state of the ICM

We study the azimuthal scatter in the radial profiles of X-ray luminous galaxy clusters, with two sets of high-resolution cosmological re-simulations obtained with the codes ENZO and GADGET2. The average gas profiles are computed for different angular sectors of the cluster projected volume, and compared with the mean cluster profiles at each radius from the center. We report that in general the level of azimuthal scatter is found to be about 10 per cent for gas density, temperature and entropy inside R200, and about 25 per cent for X-ray luminosity for the same volume. These values generally doubles going to 2 R200 from the cluster center, and are generally found to be higher (by about 20-40 percent) in the case of perturbed systems. A comparison with results from recent SUZAKU observations is discussed, showing the possibility to simply interpret the large azimuthal scatter of observables in light of our simulated results.

astro-ph.CO↗

arXiv2010

Infrared properties of the SDSS-maxBCG galaxy clusters

The physics of galaxy clusters has proven to be influenced by several processes connected with their galactic component which pollutes the ICM with metals, stars and dust. However, it is not clear whether the presence of diffuse dust can play a role in clusters physics since a characterisation of the IR properties of galaxy clusters is yet to be completely achieved. We focus on the recent work of Giard et al. (2008) who performed a stacking analysis of the IRAS data in the direction of several thousands of galaxy clusters, providing a statistical characterisation of their IR luminosity and redshift evolution. We model the IR properties of the galactic population of the SDSS-maxBCG clusters (0.1<z<0.3) in order to check if it accounts for the entire observed signal and to constrain the possible presence of other components, like dust in the ICM. Starting from the optical properties of the galaxy members, we estimate their emission in the 60 and 100 micron IRAS bands making use of modeled SEDs of different spectral types (E/S0, Sa, Sb, Sc and starburst). We also consider the evolution of the galactic population/luminosity with redshift. Our results indicate that the galactic emission, which is dominated by the contribution of star-forming galaxies, is consistent with the observed signal. In fact, our model slightly overestimates the observed fluxes, with the excess being concentrated in low-redshift clusters (z <~ 0.17). This indicates that, if present, the IR emission from intracluster dust must be very small. We obtain an upper limit on the dust-to-gas mass ratio in the ICM of Z_d <~ 5 10^-5. The excess in luminosity obtained at low redshift constitutes an indication that the cluster environment is driving a process of star-formation quenching in its galaxy members.

astro-ph.CO↗

arXiv2009

Imprints of primordial non-Gaussianities in X-ray and SZ signals from galaxy clusters

Several inflationary models predict the possibility that the primordial perturbations of the density field may contain a degree of non-Gaussianity which would influence the subsequent evolution of cosmic structures at large scales. In order to study their impact, we use a set of three cosmological DM-only simulations starting from initial conditions with different levels of non-Gaussianity: f_NL=0,+/-100. More specifically, we focus on the distribution of galaxy clusters at different redshifts and, using suitable scaling relations, we determine their X-ray and SZ signals. Our analysis allows us to estimate the differences in the logN-logS and logN-logY due to the different initial conditions and to predict the cluster counts at different redshifts expected for future surveys (eROSITA and SPT). We also use a second set of simulations assuming a different cosmological scenario to estimate how the dependence on f_NL is degenerate with respect to other parameters. Our results indicate that the effects introduced by a realistic amount of primordial non-Gaussianity are small when compared to the ones connected with current uncertainties in cosmological parameters, particularly with sigma_8. However, if future surveys will be associated with optical follow-up campaigns to determine the cluster redshift, an analysis of the samples at z>1 can provide significant constraints on f_NL. In particular we predict that the SPT cluster survey will be able to detect ~1000 clusters at z>1 for the Gaussian case, with a difference of 15-20 per cent associated to f_NL=+/-100.

astro-ph.CO↗

arXiv2009

Simulating the impact of dust cooling on the statistical properties of the intracluster medium

From the first stages of star and galaxy formation, non-gravitational processes such as ram pressure stripping, SNs, galactic winds, AGNs, galaxy-galaxy mergers, etc... lead to the enrichment of the IGM in stars, metals as well as dust, via the ejection of galactic material into the IGM. We know now that these processes shape, side by side with gravitation, the formation and the evolution of structures. We present here hydrodynamic simulations of structure formation implementing the effect of the cooling by dust on large scale structure formation. We focus on the scale of galaxy clusters and study the statistical properties of clusters. Here we present our results on the $T_X-M$ and the $L_X-M$ scaling relations which exhibit changes on both the slope and normalization when adding cooling by dust to the standard radiative cooling model. For example, the normalization of the $T_X-M$ relation changes only by a maximum of 2% at $M=10^{14}$ M$_\odot$ whereas the normalization of the $L_X-T_X$ changes by as much as 10% at $T_X=1$ keV for models that including dust cooling. Our study shows that the dust is an added non-gravitational process that contributes shaping the thermodynamical state of the hot ICM gas.

astro-ph.CO↗