arXiv subjects

Mauro Roncarelli

Publications and source records attributed to Mauro Roncarelli.

At least 19 recordsLinked to original sources

arXiv2026

DEMNUni: the Sunyaev-Zel'dovich effect in the presence of massive neutrinos and dynamical dark energy

In recent years, the study of secondary anisotropies in the Cosmic Microwave Background has become a fundamental instrument to test our understanding of the Universe. Using a set of lightcones produced with the ``Dark Energy and Massive Neutrino Universe'' $N$-body simulations, we study how different dark energy equations of state and neutrino masses impact the properties of the thermal Sunyaev-Zel'dovich (tSZ) effect, focusing on the signal arising from galaxy clusters and groups. We analyse the distribution of values for the Compton-$y$ parameter and study its angular power spectrum. We find that the distribution of the logarithmic Compton parameter can be fitted with a skewed Gaussian, with a mean that, at fixed dark energy model, decreases linearly with an approximate slope of $10 f_ν$. Regarding the power spectrum of the thermal SZ effect, we find that an increase in $\sum {m_ν}$ is observed as a power-law scaling with respect to $σ_8^{\mathrm{cb}}$, with exponents ranging from 7.3 to 8.1. We also find that models with massless neutrinos typically overestimate Compton-$y$ data extracted from Planck measurements; a better agreement with the simulations is obtained for $\sum m_ν= 0.16$ or $\sum m_ν=0.32$ eV. For all the \texttt{DEMNUni} models we forecast the cumulative signal-to-noise ratio for thermal SZ observations with the LAT instrument of the Simons Observatory; furthermore, we compute a tailored $χ_\mathrm{SNR}^2$ estimator to infer if such models can be distinguished from the reference $Λ$CDM.

astro-ph.CO↗

arXiv2024

AMICO galaxy clusters in KiDS-DR3: measuring the splashback radius from weak gravitational lensing

Context. Weak gravitational lensing offers a powerful method to investigate the projected matter density distribution within galaxy clusters, granting crucial insights into the broader landscape of dark matter on cluster scales. Aims. In this study, we make use of the large photometric galaxy cluster data set derived from the publicly available Third Data Release of the Kilo-Degree Survey, along with the associated shear signal. Our primary objective is to model the peculiar sharp transition in the cluster profile slope, that is what is commonly referred to as the splashback radius. The data set under scrutiny includes 6962 galaxy clusters, selected by AMICO - an optimised detection algorithm of galaxy clusters - on the KiDS-DR3 data, in the redshift range of 0.1 < z < 0.6, all observed at a signal-to-noise ratio greater than 3.5. Methods. Employing a comprehensive Bayesian analysis, we model the stacked excess surface mass density distribution of the clusters. We adopt a model from recent results on numerical simulations that capture the dynamics of both orbiting and infalling materials, separated by the region where the density profile slope undergoes a pronounced deepening. Results. We find that the adopted profile successfully characterizes the cluster masses, consistent with previous works, and models the deepening of the slope of the density profiles measured with weak-lensing data up to the outskirts. Moreover, we measure the splashback radius of galaxy clusters and show that its value is close to the radius within which the enclosed overdensity is 200 times the mean matter density of the Universe, while theoretical models predict a larger value consistent with a low accretion rate. This points to a potential bias of optically selected clusters preferentially characterized by a high density at small scales compared to a pure mass-selected cluster sample.

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arXiv2023

AMICO galaxy clusters in KiDS-DR3: constraints on $Λ$CDM from extreme value statistics

We constrain the $Λ$CDM cosmological parameter $σ_{8}$ by applying the extreme value statistics for galaxy cluster mass on the AMICO KiDS-DR3 catalog. We sample the posterior distribution of the parameters by considering the likelihood of observing the largest cluster mass value in a sample of $N_{\textrm{obs}} = 3644$ clusters with intrinsic richness $λ^{*} > 20$ in the redshift range $z\in[0.10, 0.60]$. We obtain $σ_{8}=0.90_{-0.18}^{+0.20}$, consistent within $1σ$ with the measurements obtained by the Planck collaboration and with previous results from cluster cosmology exploiting AMICO KiDS-DR3. The constraints could improve by applying this method to forthcoming missions, such as $\textit{Euclid}$ and LSST, which are expected to deliver thousands of distant and massive clusters.

astro-ph.CO↗

arXiv2022

AMICO galaxy clusters in KiDS-DR3: Measurement of the halo bias and power spectrum normalization from a stacked weak lensing analysis

Galaxy clusters are biased tracers of the underlying matter density field. At very large radii beyond about 10 Mpc/\textit{h}, the shear profile shows evidence of a second-halo term. This is related to the correlated matter distribution around galaxy clusters and proportional to the so-called halo bias. We present an observational analysis of the halo bias-mass relation based on the AMICO galaxy cluster catalog, comprising around 7000 candidates detected in the third release of the KiDS survey. We split the cluster sample into 14 redshift-richness bins and derive the halo bias and the virial mass in each bin by means of a stacked weak lensing analysis. The observed halo bias-mass relation and the theoretical predictions based on the $Λ$CDM standard cosmological model show an agreement within $2σ$. The mean measurements of bias and mass over the full catalog give $M_{200c} = (4.9 \pm 0.3) \times 10^{13} M_{\odot}/\textit{h}$ and $b_h σ_8^2 = 1.2 \pm 0.1$. With the additional prior of a bias-mass relation from numerical simulations, we constrain the normalization of the power spectrum with a fixed matter density $Ω_m = 0.3$, finding $σ_8 = 0.63 \pm 0.10$.

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arXiv2021

AMICO galaxy clusters in KiDS-DR3: cosmological constraints from large-scale stacked weak lensing profiles

Context. The large-scale mass distribution around dark matter haloes hosting galaxy clusters provides sensitive cosmological information. Aims. In this work, we make use of a large photometric galaxy cluster sample, constructed from the public Third Data Release of the Kilo-Degree Survey, and the corresponding shear signal, to assess cluster masses and test the concordance $Λ$-cold dark matter ($Λ$CDM) model. In particular, we study the weak gravitational lensing effects on scales beyond the cluster virial radius, where the signal is dominated by correlated and uncorrelated matter density distributions along the line-of-sight. The analysed catalogue consists of 6962 galaxy clusters, in the redshift range $0.1 \leq z \leq 0.6$ and with signal-to-noise ratio larger than 3.5. Methods. We perform a full Bayesian analysis to model the stacked shear profiles of these clusters. The adopted likelihood function considers both the small-scale 1-halo term, used primarily to constrain the cluster structural properties, and the 2-halo term, that can be used to constrain cosmological parameters. Results. We find that the adopted modelling is successful to assess both the cluster masses and the total matter density parameter, $Ω_M$, when fitting shear profiles up to the largest available scales of 35 Mpc/h. Moreover, our results provide a strong observational evidence of the 2-halo signal in the stacked gravitational lensing of galaxy clusters, further demonstrating the reliability of this probe for cosmological studies. The main result of this work is a robust constraint on $Ω_M$, assuming a flat $Λ$CDM cosmology. We get $Ω_M = 0.29 \pm 0.02$, estimated from the full posterior probability distribution, consistent with the estimates from cosmic microwave background experiments.

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arXiv2020

AMICO galaxy clusters in KiDS-DR3: galaxy population properties and their redshift dependence

A catalogue of galaxy clusters was obtained in an area of 414 sq deg up to a redshift $z\sim0.8$ from the Data Release 3 of the Kilo-Degree Survey (KiDS-DR3), using the Adaptive Matched Identifier of Clustered Objects (AMICO) algorithm. The catalogue and the calibration of the richness-mass relation were presented in two companion papers. Here we describe the selection of the cluster central galaxy and the classification of blue and red cluster members, and analyze the main cluster properties, such as the red/blue fraction, cluster mass, brightness and stellar mass of the central galaxy, and their dependence on redshift and cluster richness. We use the Illustris-TNG simulation, which represents the state-of-the-art cosmological simulation of galaxy formation, as a benchmark for the interpretation of the results. A good agreement with simulations is found at low redshifts ($z \le 0.4$), while at higher redshifts the simulations indicate a lower fraction of blue galaxies than what found in the KiDS-AMICO catalogue: we argue that this may be due to an underestimate of star-forming galaxies in the simulations. The selection of clusters with a larger magnitude difference between the two brightest central galaxies, which may indicate a more relaxed cluster dynamical status, improves the agreement between the observed and simulated cluster mass and stellar mass of the central galaxy. We also find that at a given cluster mass the stellar mass of blue central galaxies is lower than that of the red ones.

astro-ph.GA↗

arXiv2020

CoMaLit -- VI. Intrinsic scatter in stacked relations. The weak lensing AMICO galaxy clusters in KiDS-DR3

Unbiased and precise mass calibration of galaxy clusters is crucial to fully exploit galaxy clusters as cosmological probes. Stacking of weak lensing signal allows us to measure observable-mass relations down to less massive halos halos without extrapolation. We propose a Bayesian inference method to constrain the intrinsic scatter of the mass proxy in stacked analyses. The scatter of the stacked data is rescaled with respect to the individual scatter based on the number of binned clusters. We apply this method to the galaxy clusters detected with the AMICO (Adaptive Matched Identifier of Clustered Objects) algorithm in the third data release of the Kilo-Degree Survey. The results confirm the optical richness as a low scatter mass proxy. Based on the optical richness and the calibrated weak lensing mass-richness relation, mass of individual objects down to ~10^13 solar masses can be estimated with a precision of ~20 per cent.

astro-ph.CO↗

arXiv2019

Spectral imaging of the thermal Sunyaev-Zel'dovich effect in X-COP galaxy clusters: method and validation

The imaging of galaxy clusters through the Sunyaev--Zel'dovich effect is a valuable tool to probe the thermal pressure of the intra-cluster gas, especially in the outermost regions where X-ray observations suffer from photon statistics. For the first time, we produce maps of the Comptonization parameter by applying a locally parametric algorithm for sparse component separation to the latest frequency maps released by Planck. The algorithm takes into account properties of real cluster data through the two-component modelling of the spectral energy density of thermal dust, and the masking of bright point sources. Its robustness has been improved in the low signal-to-noise regime, thanks to the implementation of a deconvolution of Planck beams in the chi-square minimisation of each wavelet coefficient. We applied this procedure to twelve low-redshift galaxy clusters detected by Planck with the highest signal-to-noise ratio, considered in the XMM Cluster Oustkirts Project (X-COP). Our images show the presence of anisotropic features, such as small-scale blobs and filamentary substructures that are located in the outskirts of a number of clusters in the sample. The significance of their detection is established via a bootstrap-based procedure we propose here for the first time. In particular, we present a qualitative comparison with X-ray data for two interesting systems, namely A2029 and RXCJ1825. Our results are in agreement with the features detected in the outskirts of the clusters in the two bands.

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arXiv2019

Probing Macro-Scale Gas Motions and Turbulence in Diffuse Cosmic Plasmas

Clusters of galaxies, the largest collapsed structures in the Universe, are located at the intersection of extended filaments of baryons and dark matter. Cosmological accretion onto clusters through large scale filaments adds material at cluster outskirts. Kinetic energy in the form of bulk motions and turbulence due to this accretion provides a form of pressure support against gravity, supplemental to thermal pressure. Significant amount of non-thermal pressure support could bias cluster masses derived assuming hydrostatic equilibrium, the primary proxy for cluster cosmology studies. Sensitive measurements of Doppler broadening and shift of astrophysical lines, and the relative fluctuations in thermodynamical quantities (e.g., density, pressure, and entropy) are primary diagnostic tools. Forthcoming planned and proposed X-ray (with large etendue, throughput, and high spectral resolution) and SZ observatories will provide crucial information on the assembly and virialisation processes of clusters, involving turbulent eddies cascading at various spatial scales and larger gas bulk motions in their external regions to the depth or their potential wells.

astro-ph.CO↗

arXiv2019

AMICO galaxy clusters in KiDS-DR3: weak-lensing mass calibration

We present the mass calibration for galaxy clusters detected with the AMICO code in KiDS DR3 data. The cluster sample comprises $\sim$ 7000 objects and covers the redshift range 0.1 < $z$ < 0.6. We perform a weak lensing stacked analysis by binning the clusters according to redshift and two different mass proxies provided by AMICO, namely the amplitude $A$ (measure of galaxy abundance through an optimal filter) and the richness $λ^*$ (sum of membership probabilities in a consistent radial and magnitude range across redshift). For each bin, we model the data as a truncated NFW profile plus a 2-halo term, taking into account uncertainties related to concentration and miscentring. From the retrieved estimates of the mean halo masses, we construct the $A$-$M_{200}$ and the $λ^*$-$M_{200}$ relations. The relations extend over more than one order of magnitude in mass, down to $M_{200} \sim 2 (5) \times 10^{13} M_\odot/h$ at $z$ = 0.2 (0.5), with small evolution in redshift. The logarithmic slope is $\sim 2.0$ for the $A$-mass relation, and $\sim 1.7$ for the $λ^*$-mass relation, consistent with previous estimations on mock catalogues and coherent with the different nature of the two observables.

astro-ph.CO↗

arXiv2018

AMICO galaxy clusters in KiDS-DR3: sample properties and selection function

We present the first catalogue of galaxy cluster candidates derived from the third data release of the Kilo Degree Survey (KiDS-DR3). The sample of clusters has been produced using the Adaptive Matched Identifier of Clustered Objects (AMICO) algorithm. In this analysis AMICO takes advantage of the luminosity and spatial distribution of galaxies only, not considering colours. In this way, we prevent any selection effect related to the presence or absence of the red-sequence in the clusters. The catalogue contains 7988 candidate galaxy clusters in the redshift range 0.1 3.5 with a purity approaching 95% over the entire redshift range. In addition to the catalogue of galaxy clusters we also provide a catalogue of galaxies with their probabilistic association to galaxy clusters. We quantify the sample purity, completeness and the uncertainties of the detection properties, such as richness, redshift, and position, by means of mock galaxy catalogues derived directly from the data. This preserves their statistical properties including photo-z uncertainties, unknown absorption across the survey, missing data, spatial correlation of galaxies and galaxy clusters. Being based on the real data, such mock catalogues do not have to rely on the assumptions on which numerical simulations and semi-analytic models are based on. This paper is the first of a series of papers in which we discuss the details and physical properties of the sample presented in this work.

astro-ph.CO↗

arXiv2017

AMICO: optimised detection of galaxy clusters in photometric surveys

We present AMICO (Adaptive Matched Identifier of Clustered Objects), a new algorithm for the detection of galaxy clusters in photometric surveys. AMICO is based on the Optimal Filtering technique, which allows to maximise the signal-to-noise ratio of the clusters. In this work we focus on the new iterative approach to the extraction of cluster candidates from the map produced by the filter. In particular, we provide a definition of membership probability for the galaxies close to any cluster candidate, which allows us to remove its imprint from the map, allowing the detection of smaller structures. As demonstrated in our tests, this method allows the deblending of close-by and aligned structures in more than $50\%$ of the cases for objects at radial distance equal to $0.5 \times R_{200}$ or redshift distance equal to $2 \times σ_z$, being $σ_z$ the typical uncertainty of photometric redshifts. Running AMICO on mocks derived from N-body simulations and semi-analytical modelling of the galaxy evolution, we obtain a consistent mass-amplitude relation through the redshift range $0.3 < z < 1$, with a logarithmic slope $\sim 0.55$ and a logarithmic scatter $\sim 0.14$. The fraction of false detections is steeply decreasing with S/N, and negligible at S/N > 5.

astro-ph.CO↗

arXiv2017

The kinematic Sunyaev-Zel'dovich effect of the large-scale structure (I): dependence on neutrino mass

The study of neutrinos in astrophysics requires the combination of different observational probes. The temperature anisotropies of the cosmic microwave background induced via the kinematic Sunyaev-Zel'dovich (kSZ) effect may provide interesting information since they are expected to receive significant contribution from high-redshift plasma. We present a set of cosmological hydrodynamical simulations that include a treatment of the neutrino component considering four different sum of neutrino masses: $Σm_ν=(0,0.15,0.3,0.6)$ eV. Using their outputs, we modelled the kSZ effect due to the large-scale structure after the reionization by producing mock maps, then computed the kSZ power spectrum and studied how it depends on $z_{\rm re}$ and $Σm_ν$. We also run a set of four simulations to study and correct possible systematics due to resolution, finite box size and astrophysics. With massless neutrinos we obtain $\mathcal{D}^{\rm kSZ}_{3000}=4.0$ $μ{\rm K}^2$ ($z_{\rm re}$=8.8), enough to account for all of the kSZ signal of $\mathcal{D}^{\rm kSZ}_{3000}=(2.9\pm1.3)$ $μ{\rm K}^2$ measured with the South Pole Telescope. This translates into an upper limit on the kSZ effect due to patchy reionization of $\mathcal{D}^{\rm kSZ,patchy}_{3000}<1.0$ $μ{\rm K}^2$ (95 per cent confidence level). Massive neutrinos induce a damping of kSZ effect power of about 8, 12 and 40 per cent for $Σm_ν=(0.15,0.3,0.6)$ eV, respectively. We study the dependence of the kSZ signal with $z_{\rm re}$ and the neutrino mass fraction, $f_ν$, and obtain $\mathcal{D}^{\rm kSZ}_{3000}\propto z_{\rm re}^{0.26}(1-f_ν)^{14.3}$. Interestingly, the scaling with $f_ν$ is significantly shallower with respect to the equivalent thermal SZ effect, and may be used to break the degeneracy with other cosmological parameters.

astro-ph.CO↗

arXiv2015

Constraints on $Ω_\mathrm{m}$ and $σ_8$ from the potential-based cluster temperature function

The abundance of galaxy clusters is in principle a powerful tool to constrain cosmological parameters, especially $Ω_\mathrm{m}$ and $σ_8$, due to the exponential dependence in the high-mass regime. While the best observables are the X-ray temperature and luminosity, the abundance of galaxy clusters, however, is conventionally predicted as a function of mass. Hence, the intrinsic scatter and the uncertainties in the scaling relations between mass and either temperature or luminosity lower the reliability of galaxy clusters to constrain cosmological parameters. In this article, we further refine the X-ray temperature function for galaxy clusters by Angrick et al., which is based on the statistics of perturbations in the cosmic gravitational potential and proposed to replace the classical mass-based temperature function, by including a refined analytic merger model and compare the theoretical prediction to results from a cosmological hydrodynamical simulation. Although we find already a good agreement if we compare with a cluster temperature function based on the mass-weighted temperature, including a redshift-dependent scaling between mass-based and spectroscopic temperature yields even better agreement between theoretical model and numerical results. As a proof of concept, incorporating this additional scaling in our model, we constrain the cosmological parameters $Ω_\mathrm{m}$ and $σ_8$ from an X-ray sample of galaxy clusters and tentatively find agreement with the recent cosmic microwave background based results from the Planck mission at 1$σ$-level.

astro-ph.CO↗

arXiv2015

Searching for galaxy clusters in the VST-KiDS Survey

We present the methods and first results of the search for galaxy clusters in the Kilo Degree Survey (KiDS). The adopted algorithm and the criterium for selecting the member galaxies are illustrated. Here we report the preliminary results obtained over a small area (7 sq. degrees), and the comparison of our cluster candidates with those found in the RedMapper and SZ Planck catalogues; the analysis to a larger area (148 sq. degrees) is currently in progress. By the KiDS cluster search, we expect to increase the completeness of the clusters catalogue to z = 0.6-0.7 compared to RedMapper.

astro-ph.CO↗

arXiv2014

The effect of massive neutrinos on the Sunyaev-Zeldovich and X-ray observables of galaxy clusters

Massive neutrinos are expected to influence the formation of the large-scale structure of the Universe, depending on the value of their total mass, $Σm_ν$. In particular Planck data indicate that a non-zero $Σm_ν$ may help to reconcile CMB data with Sunyaev-Zel'dovich (SZ) cluster surveys. In order to study the impact of neutrinos on the SZ and X-ray cluster properties we run a set of six very large cosmological simulations (8$h^{-3}$ Gpc$^3$ comoving volume) that include a massive neutrino particle component: we consider the values of $Σm_ν$ = (0, 0.17, 0.34) eV in two cosmological scenarios to test possible degeneracies. Using the halo catalogues extracted from their outputs we produce 50 mock light-cones and, assuming suitable scaling relations, we determine how massive neutrinos affect SZ and X-ray cluster counts, the $y$-parameter and its power spectrum. We provide forecasts for the South Pole Telescope (SPT) and eROSITA cluster surveys, showing that the number of expected detections is reduced by 40 per cent when assuming $Σm_ν$ =0.34 eV with respect to a model with massless neutrinos. However the degeneracy with $σ_8$ and $Ω_m$ is strong, in particular for X-ray data, requiring the use of additional probes to break it. The $y$-parameter properties are also highly influenced by the neutrino mass fraction, $f_ν$, with $<\,y\,>\propto(1-f_ν)^{20}$, considering the cluster component only, and the normalization of the SZ power spectrum is proportional to $(1-f_ν)^{25-30}$. Comparing our findings with SPT and Atacama Cosmology Telescope measurements at $\ell$ = 3000 indicates that, when Planck cosmological parameters are assumed, a value of $Σm_ν\simeq0.34$ eV is required to fit with the data.

astro-ph.CO↗

arXiv2013

The Hot and Energetic Universe: The missing baryons and the warm-hot intergalactic medium

The backbone of the large-scale structure of the Universe is determined by processes on a cosmological scale and by the gravitational interaction of the dominant dark matter. However, the mobile baryon population shapes the appearance of these structures. Theory predicts that most of the baryons reside in vast unvirialized filamentary structures that connect galaxy groups and clusters, but the observational evidence is currently lacking. Because the majority of the baryons are supposed to exist in a large-scale, hot and dilute gaseous phase, X-rays provide the ideal tool to progress our understanding. Observations with the Athena+ X-ray Integral Field Unit will reveal the location, chemical composition, physical state and dynamics of the active population of baryons.

astro-ph.HE↗

arXiv2013

Outskirts of Galaxy Clusters

Until recently, only about 10% of the total intracluster gas volume had been studied with high accuracy, leaving a vast region essentially unexplored. This is now changing and a wide area of hot gas physics and chemistry awaits discovery in galaxy cluster outskirts. Also, robust large-scale total mass profiles and maps are within reach. First observational and theoretical results in this emerging field have been achieved in recent years with sometimes surprising findings. Here, we summarize and illustrate the relevant underlying physical and chemical processes and review the recent progress in X-ray, Sunyaev--Zel'dovich, and weak gravitational lensing observations of cluster outskirts, including also brief discussions of technical challenges and possible future improvements.

astro-ph.CO↗