arXiv subjects

Vicent Quilis

Publications and source records attributed to Vicent Quilis.

At least 19 recordsLinked to original sources

arXiv2025

The eventful life journey of galaxy clusters. II. Impact of mass accretion on the thermodynamical structure of the ICM

Context. The internal structure of the intracluster medium (ICM) is tightly linked to the assembly history and physical processes in groups and clusters, but the role of recent accretion in shaping these profiles has not been fully explored. Aims. We investigate to what extent mass accretion accounts for the variability in ICM density and thermodynamic profiles, and what can present-day structures reveal about their formation histories. Methods. We analyze a hydrodynamical cosmological simulation including gas cooling but no feedback, to isolate the effects of heating from structure formation. Median profiles of ICM quantities are introduced as a robust description of the bulk ICM. We then examine correlations between mass accretion rates or assembly indicators with the profiles of temperature, entropy, pressure, gas and dark-matter density, as well as their scatter. Results. Accretion in the last dynamical time strongly lowers central gas densities, while leaving dark matter largely unaffected, producing a distinct signature in the baryon depletion function. Pressure and entropy show the clearest dependence on accretion, whereas temperature is less sensitive. The radii of steepest entropy, temperature, and pressure shift inward by $\sim (10-20)\%$ between high- and low-accretion subsamples. Assembly-state indicators are also related to the location of these features, and accretion correlates with the parameters of common fitting functions for density, pressure, and entropy. Conclusions. Recent accretion leaves measurable imprints on the ICM structure, highlighting the potential of thermodynamic profiles as diagnostics of cluster growth history.

astro-ph.CO↗

arXiv2025

The signature of major mergers on the hydrostatic mass bias of galaxy clusters

While galaxy cluster masses are fundamental cosmological observables, estimates based on intra-cluster medium observations rely on hydrostatic equilibrium, introducing a systematic bias. We investigate how mergers drive the time evolution of this hydrostatic mass bias, identifying the dominant physical mechanisms and their dependence on dynamical state and merger history. Using a high-resolution AMR Eulerian+$N$-body cosmological simulation, we analyse a sample of cluster mergers within $1.5 \leq z \leq 0$, comparing true and hydrostatic masses derived from gas density and temperature profiles, and tracing their evolution. At $z=0$, the hydrostatic mass bias shows a mild correlation with dynamical state. During major mergers, the bias follows a characteristic trend: a sharp negative dip around the merger time, a transient positive peak, and a gradual return to pre-merger levels. This behaviour is primarily driven by morphological and dynamical reconfigurations of the gas density within the ICM, while thermodynamical processes play a secondary role. The pattern shows no strong dependence on secondary parameters, such as mass ratio or impact parameter, but it can be fitted to a simple time-dependent functional form. This trend is present at radii $r\le R_{\mathrm{vir}}$, although with reduced amplitude and shorter timescales as the radius decreases. Hydrostatic mass bias is closely linked, albeit in a non-trivial way, with the merging history of galaxy clusters. We find that the bias values are weakly correlated with the dynamical state of clusters. Nevertheless, our results give a robust estimation of the hydrostatic mass bias values in the pre-merger, merging, and post-merger phases. These findings highlight the importance of delving deeper into the observational assessment of cluster assembly state in order to improve mass estimations for cosmological analyses.

astro-ph.CO↗

arXiv2025

AVISM: Algorithm for Void Identification in coSMology

Cosmic voids are key elements in our understanding of the large-scale structure of the Universe. They are crucial to constrain cosmological parameters, understand the structure formation and evolution of our Universe, and they could also be pristine laboratories for studying galaxy formation without all the hassle due to environmental effects. Thus, the ability to accurately and consistently identify voids, both in numerical simulations and in observations, becomes mandatory. We present Algorithm for Void Identification in coSMology (AVISM), a new void finder for analysing both cosmological simulation outputs and observational galaxy catalogues. In the first case, the code should handle raw particle or cell data, dark matter halos or synthetic galaxy catalogues. In the case of observational data, the code should be coupled with external tools providing with the required dynamical information to apply the algorithm. A set of numerical tests designed to assess the code's capabilities are carried out. AVISM's performance is also compared, both statistically and on a one-to-one basis, with the DIVE and ZOBOV state-of-the-art void finders using as input a dark matter halo catalogue from a large-volume cosmological simulation. An application to a galaxy survey is provided to demonstrate the code's ability to handle real data. We have designed a new void finder algorithm that combines geometrical and dynamical information to identify void regions plus a hierarchical merging process to reconstruct the whole 3D structure of the void. The outcome of this process is a void catalogue with complex boundaries without assuming a prior shape. This process can be repeated at different levels of resolution using finer grids, leading to a list of voids-in-voids and a proper description of void substructure.

astro-ph.CO↗

arXiv2025

The eventful life journey of galaxy clusters. I. Impact of DM halo and ICM properties on their full assembly histories

Context. Galaxy clusters assemble over gigayears in a very anisotropic environment, which causes a remarkable diversity in their mass assembly histories (MAH). Aims. In this work, we have aimed to understand how the present-day properties of the dark matter halo and the intracluster medium are related to the whole evolution of these structures. Methods. To this end, we analysed a $Λ$CDM hydrodynamical+$N$-Body simulation of a $(100 \, h^{-1} \mathrm{Mpc})^3$ volume, containing over 30 clusters and 300 groups, and looked at the individual and the stacked MAHs (determined from complete merger trees) in relation to properties of the DM haloes and the ICM at fixed cosmic time (indicators of assembly state). Results. The ensemble MAHs are well separated when stacked in bins of these indicators, yielding clear dependencies of evolutionary properties (such as formation redshift) on fix-time halo properties. Additionally, we find that different indicators are informative about distinct epochs of accretion. Finally, by summarising the complex MAH diversity with two parameters, we describe how different indicators bring complementary information in different directions of this biparametric space. Overall, halo spin and a combined indicator appear to be the ones encoding the most information about the MAH. Conclusions. The results shown here add up to the idea that the dynamical state of cosmic structures is a multifaceted concept, and warn that single indicators are incapable of capturing the whole complexity of the process. This work sheds light on the nature of this characterisation by untangling precisely when and how several indicators are informative about. In turn, this can provide clues to better constrain the MAH of observed structures.

astro-ph.CO↗

arXiv2024

Vortex-p: a Helmholtz-Hodge and Reynolds decomposition algorithm for particle-based simulations

Astrophysical turbulent flows display an intrinsically multi-scale nature, making their numerical simulation and the subsequent analyses of simulated data a complex problem. In particular, two fundamental steps in the study of turbulent velocity fields are the Helmholtz-Hodge decomposition (compressive+solenoidal; HHD) and the Reynolds decomposition (bulk+turbulent; RD). These problems are relatively simple to perform numerically for uniformly-sampled data, such as the one emerging from Eulerian, fix-grid simulations; but their computation is remarkably more complex in the case of non-uniformly sampled data, such as the one stemming from particle-based or meshless simulations. In this paper, we describe, implement and test vortex-p, a publicly available tool evolved from the vortex code, to perform both these decompositions upon the velocity fields of particle-based simulations, either from smoothed particle hydrodynamics (SPH), moving-mesh or meshless codes. The algorithm relies on the creation of an ad-hoc adaptive mesh refinement (AMR) set of grids, on which the input velocity field is represented. HHD is then addressed by means of elliptic solvers, while for the RD we adapt an iterative, multi-scale filter. We perform a series of idealised tests to assess the accuracy, convergence and scaling of the code. Finally, we present some applications of the code to various SPH and meshless finite-mass (MFM) simulations of galaxy clusters performed with OpenGadget3, with different resolutions and physics, to showcase the capabilities of the code.

astro-ph.IM↗

arXiv2024

Cosmic accretion shocks as a tool to measure the dark matter mass of galaxy clusters

Cosmological accretion shocks created during the formation of galaxy clusters are a ubiquitous phenomenon all around the Universe. These shocks, and their features, are intimately related with the gravitational energy put into play during galaxy cluster formation. Studying a sample of simulated galaxy clusters and their associated accretion shocks, we show that objects in our sample sit in a plane within the three dimensional-space of cluster total mass, shock radius, and Mach number (a measure of shock intensity). Using this relation, and considering that forthcoming new observations will be able to measure shock radii and intensities, we put forward the idea that the dark matter content of galaxy clusters could be indirectly measured with an error up to around 30 per cent at the $1σ$ confidence level. This procedure would be a new and independent method to measure the dark matter mass in cosmic structures, and a novel constraint to the accepted $Λ$CDM paradigm.

astro-ph.CO↗

arXiv2024

The imprints of galaxy cluster internal dynamics on the Sunyaev-Zeldovich effect

Forthcoming measurements of the Sunyaev-Zeldovich (SZ) effect in galaxy clusters will dramatically improve our understanding of the main intra-cluster medium (ICM) properties and how they depend on the particular thermal and dynamical state of the associated clusters. Using a sample of simulated galaxy clusters we assess the impact of the ICM internal dynamics on both the thermal and kinetic SZ effects (tSZ and kSZ, respectively). We produce synthetic maps of the SZ effect, for the simulated clusters. For each galaxy cluster in the sample, its dynamical state is estimated by using a combination of well-established indicators. We use the correlations between SZ maps and cluster dynamical state, to look for the imprints of the evolutionary events, mainly mergers, on the SZ signals. The kinetic effect shows a remarkable correlation with the dynamical state: unrelaxed clusters present a higher radial profile and an overall stronger signal at all masses and radii. Furthermore, the kSZ signal is correlated with rotation for relaxed clusters, while for the disturbed systems the effect is dominated by other motions such as bulk flows, turbulence, etc. The kSZ effect shows a dipolar pattern when averaging over cluster dynamical classes, especially for the relaxed population. This feature can be exploited to stack multiple kSZ maps in order to recover a stronger dipole signal that would be correlated with the global rotation properties of the sample. The SZ effect can be used as a tool to estimate the dynamical state of galaxy clusters, especially to segregate those clusters with a quiescent evolution from those with a rich record of recent merger events. Our results suggest that the forthcoming observational data measuring the SZ signal in clusters could be used as a complementary strategy to classify the evolutionary history of galaxy clusters.

astro-ph.CO↗

arXiv2023

On the choice of the most suitable indicator for the assembly state of dark matter haloes through cosmic time

The dynamical state and morphological features of galaxies and galaxy clusters, and their high-redshift precursors, are tightly connected with their assembly history, encoding crucial information about the formation and evolution of such cosmic structures. As a first step towards finding an optimal indicator of the assembly state of observed structures, we use a cosmological simulation of a moderate volume to critically examine the best definition of an indicator that is able to discriminate dark matter haloes undergoing mergers and/or strong accretion from haloes experimenting a relaxed evolution. Using a combination of centre offset, virial ratio, mean radial velocity, sparsity and ellipticity of the dark matter halo, we study how the thresholds on these parameters, as well as their relative weights, should evolve with redshift to provide the best classification possible. This allows us to split a sample of haloes in a totally relaxed, a marginally relaxed and an unrelaxed subsamples. The resulting classification strongly correlates with the merging activity obtained from the analysis of complete merger trees extracted from whole simulation data. The results on how the different indicators depend on redshift and halo mass, and their optimal combination to better match the true assembly history of haloes, could constitute relevant hints to find a suitable set of indicators applicable to observational data.

astro-ph.CO↗

arXiv2022

The halo finding problem revisited: a deep revision of the ASOHF code

Context. New-generation cosmological simulations are providing huge amounts of data, whose analysis becomes itself a cutting-edge computational problem. In particular, the identification of gravitationally bound structures, known as halo finding, is one of the main analyses. A handful of codes developed to tackle this task have been presented during the last years. Aims. We present a deep revision of the already existing code ASOHF. The algorithm has been throughfully redesigned in order to improve its capabilities to find bound structures and substructures, both using dark matter particles and stars, its parallel performance, and its abilities to handle simulation outputs with vast amounts of particles. This upgraded version of ASOHF is conceived to be a publicly available tool. Methods. A battery of idealised and realistic tests are presented in order to assess the performance of the new version of the halo finder. Results. In the idealised tests, ASOHF produces excellent results, being able to find virtually all the structures and substructures placed within the computational domain. When applied to realistic data from simulations, the performance of our finder is fully consistent with the results from other commonly used halo finders, with remarkable performance in substructure detection. Besides, ASOHF turns out to be extremely efficient in terms of computational cost. Conclusions. We present a public, deeply revised version of the ASOHF halo finder. The new version of the code produces remarkable results finding haloes and subhaloes in cosmological simulations, with an excellent parallel performance and with a contained computational cost.

astro-ph.IM↗

arXiv2021

Long-term FRII jet evolution in dense environments

We present long-term numerical three-dimensional simulations of a relativistic outflow propagating through a galactic ambient medium and environment, up to distances $\sim 100$~kpc. Our aim is to study the role of dense media in the global dynamics of the radio source. We use a relativistic gas equation of state, and a basic description of thermal cooling terms. In previous work, we showed that a linear perturbation could enhance the jet propagation during the early phases of evolution, by introducing obliquity to the jet reverse shock. Here, we show that this effect is reduced in denser media. We find that the dentist-drill effect acts earlier, due to slower jet propagation and an increased growth of the helical instability. The global morphology of the jet is less elongated, with more prominent lobes. The fundamental physical parameters of the jet generated structure derived from our simulations fall within the estimated values derived for FRII jets in the 3C sample. In agreement with previous axisymmetric and three dimensional simulations in lower density media, we conclude that shock heating of the interstellar and intergalactic media is very efficient in the case of powerful, relativistic jets.

astro-ph.HE↗

arXiv2021

Void replenishment: how voids accrete matter over cosmic history

Cosmic voids are underdense regions filling up most of the volume in the Universe. They are expected to emerge in regions comprising negative initial density fluctuations, and subsequently expand as the matter around them collapses and forms walls, filaments and clusters. We report results from the analysis of a cosmological simulation specially designed to accurately describe low-density regions, such as cosmic voids. Contrary to the common expectation, we find that voids also experience significant mass inflows over cosmic history. On average, $10\%$ of the mass of voids in the sample at $z \sim 0$ is accreted from overdense regions, reaching values beyond $35\%$ for a significant fraction of voids. More than half of the mass entering the voids lingers on periods of time $\sim 10 \, \mathrm{Gyr}$ well inside them, reaching inner radii. This would imply that part of the gas lying inside voids at a given time proceeds from overdense regions (e.g., clusters or filaments), where it could have been pre-processed, thus challenging the scenario of galaxy formation in voids, and dissenting from the idea of being pristine environments.

astro-ph.CO↗

arXiv2021

Exploring the role of cosmological shock waves in the Dianoga simulations of galaxy clusters

Cosmological shock waves are ubiquitous to cosmic structure formation and evolution. As a consequence, they play a major role in the energy distribution and thermalization of the intergalactic medium (IGM). We analyze the Mach number distribution in the Dianoga simulations of galaxy clusters performed with the SPH code GADGET-3. The simulations include the effects of radiative cooling, star formation, metal enrichment, supernova and active galactic nuclei feedback. A grid-based shock-finding algorithm is applied in post-processing to the outputs of the simulations. This procedure allows us to explore in detail the distribution of shocked cells and their strengths as a function of cluster mass, redshift and baryonic physics. We also pay special attention to the connection between shock waves and the cool-core/non-cool core (CC/NCC) state and the global dynamical status of the simulated clusters. In terms of general shock statistics, we obtain a broad agreement with previous works, with weak (low-Mach number) shocks filling most of the volume and processing most of the total thermal energy flux. As a function of cluster mass, we find that massive clusters seem more efficient in thermalising the IGM and tend to show larger external accretion shocks than less massive systems. We do not find any relevant difference between CC and NCC clusters. However, we find a mild dependence of the radial distribution of the shock Mach number on the cluster dynamical state, with disturbed systems showing stronger shocks than regular ones throughout the cluster volume.

astro-ph.CO↗

arXiv2021

An estimate of the gravitational-wave background from the observed cosmological distribution of quasars

We study the gravitational-wave background from the observed cosmological quasar distribution. Using the DR9Q quasar catalogue from the ninth data release of the Sloan Digital Sky Survey (SDSS), we create a complete, statistically consistent sample of quasars from $z=0.3$ to $5.4$. Employing the spectroscopic information from the catalogue we estimate the masses of the supermassive black holes hosted by the quasars in the sample, resulting in a log-normal distribution of mean $10^{8.32\pm0.33}M_{\odot}$. The computation of the individual gravitational-wave strains relies on specific functional forms derived from simulations of gravitational collapse and mergers of massive black hole binaries. The background gravitational-wave emission is assembled by adding up the individual signals from each quasar modelled as plane waves whose interference can be constructive or destructive depending on the quasar evolutionary state. Our results indicate that the estimated gravitational-wave background discussed in this work could only be marginally detectable by LISA. This conclusion might change if more complete quasar catalogs than that provided by the SDSS were available.

gr-qc↗

arXiv2021

Troubled cosmic flows: turbulence, enstrophy and helicity from the assembly history of the intracluster medium

Both simulations and observations have shown that turbulence is a pervasive phenomenon in cosmic scenarios, yet it is particularly difficult to model numerically due to its intrinsically multiscale character which demands high resolutions. Additionally, turbulence is tightly connected to the dynamical state and the formation history of galaxies and galaxy clusters, producing a diverse phenomenlogy which requires large samples of such structures to attain robust conclusions. In this work, we use an adaptive mesh refinement (AMR) cosmological simulation to explore the generation and dissipation of turbulence in galaxy clusters, in connection to its assembly history. We find that major mergers, and more generally accretion of gas, is the main process driving turbulence in the intracluster medium. We have especially focused on solenoidal turbulence, which can be quantified through enstrophy. Our results seem to confirm a scenario for its generation which involves baroclinicity and compression at the external (accretion) and internal (merger) shocks, followed by vortex stretching downstream of them. We have also looked at the infall of mass to the cluster beyond its virial boundary, finding that gas follows trajectories with some degree of helicity, as it has already developed some vorticity in the external shocks.

astro-ph.CO↗

arXiv2021

Unravelling cosmic velocity flows: a Helmholtz-Hodge decomposition algorithm for cosmological simulations

In the context of intra-cluster medium turbulence, it is essential to be able to split the turbulent velocity field in a compressive and a solenoidal component. We describe and implement a new method for this aim, i.e., performing a Helmholtz-Hodge decomposition, in multi-grid, multi-resolution descriptions, focusing on (but not being restricted to) the outputs of AMR cosmological simulations. The method is based on solving elliptic equations for a scalar and a vector potential, from which the compressive and the solenoidal velocity fields, respectively, are derived through differentiation. These equations are addressed using a combination of Fourier (for the base grid) and iterative (for the refinement grids) methods. We present several idealised tests for our implementation, reporting typical median errors in the order of $1\unicode{x2030}$-$1\%$, and with 95-percentile errors below a few percents. Additionally, we also apply the code to the outcomes of a cosmological simulation, achieving similar accuracy at all resolutions, even in the case of highly non-linear velocity fields. We finally take a closer look to the decomposition of the velocity field around a massive galaxy cluster.

astro-ph.IM↗

arXiv2020

On the accretion history of galaxy clusters: temporal and spatial distribution

We analyse the results of an Eulerian AMR cosmological simulation in order to quantify the mass growth of galaxy clusters, exploring the differences between dark matter and baryons. We have determined the mass assembly histories (MAHs) of each of the mass components and computed several proxies for the instantaneous mass accretion rate (MAR). The mass growth of both components is clearly dominated by the contribution of major mergers, but high MARs can also occur during smooth accretion periods. We explored the correlations between MARs, merger events and clusters' environments, finding the mean densities in $1 \leq r/R_{200m} \leq 1.5$ to correlate strongly with $Γ_{200m}$ in massive clusters which undergo major mergers through their MAH. From the study of the dark matter velocity profiles, we find a strong anticorrelation between the MAR proxies $Γ_{200m}$ and $α_{200m}$. Last, we present a novel approach to study the angularly-resolved distribution of gas accretion flows in simulations, which allows to extract and interpret the main contributions to the accretion picture and to assess systematic differences between the thermodynamical properties of each of these contributions using multipolar analysis. We have preliminarily applied the method to the best numerically-resolved cluster in our simulation. Amongst the most remarkable results, we find that the gas infalling through the cosmic filaments has systematically lower entropy compared to the isotropic component, but we do not find a clear distinction in temperature.

astro-ph.GA↗

arXiv2020

Cosmic magnetic fields with MASCLET: an application to galaxy clusters

We describe and test a new version of the adaptive mesh refinement (AMR) cosmological code MASCLET. The new version of the code includes all the ingredients of its previous version plus a description of the evolution of the magnetic field under the approximation of the ideal magneto-hydrodynamics (MHD). To preserve the divergence-free condition of MHD, the original divergence cleaning algorithm of Dedner et al. (2002) is implemented. We present a set of well-known 1D and 2D tests, such as several shock-tube problems, the fast rotor and the Orszag-Tang vortex. The performance of the code in all the tests is excellent with estimated median relative errors of $\nabla \cdot {\bf B}$ in the 2D tests smaller than $5 \times 10^{-5}$ for the fast rotor test, and $5 \times 10^{-3}$ for the Orszag-Tang vortex. As an astrophysical application of the code, we present a simulation of a cosmological box of 40 comoving Mpc side length in which a primordial uniform comoving magnetic field of strength 0.1 nG is seeded. The simulation shows how the magnetic field is channelled along the filaments of gas and is concentrated and amplified within galaxy clusters. Comparison with the values expected from pure compression reveals an additional amplification of the magnetic field caused by turbulence in the central region of the cluster. Values of the order of $\sim 1 μ$G are obtained in clusters at $z\sim 0$ with median relative errors of $\nabla \cdot {\bf B}$ below 0.4\%. The implications of a proper description of the dynamics of the magnetic field and their possible observational counterparts in future facilities are discussed.

astro-ph.CO↗

arXiv2018

Long-term FRII jet evolution: Clues from three-dimensional simulations

We present a long-term numerical three-dimensional simulation of a relativistic outflow designed to be compared with previous results from axisymmetric, two-dimensional simulations, with existing analytical models and state-of-art observations. We follow the jet evolution from 1~kpc to 200~kpc, using a relativistic gas equation of state and a galactic profile for the ambient medium. We also show results from smaller scale simulations aimed to test convergence and different three-dimensional effects. We conclude that jet propagation can be faster than expected from axisymmetric simulations, covering tens of kiloparsecs in a few million years, until the dentist drill effect produced by the growth of helical instabilities slows down the propagation speed of the jet head. A comparison of key physical parameters of the jet structure as obtained from the simulations with values derived from observations of FRII sources reveals good agreement. Our simulations show that shock heating can play a significant role in the feedback from active galaxies, confirming previous 2D results. A proper description of galactic jets as a relativistic scenario, both dynamical and thermodynamical, reveals an extremely fast and efficient feedback process reheating the ICM, and therefore, with dramatic consequences on the galactic evolution. Our results point towards FRII jets as the source of the energetic electrons observed in radio relics.

astro-ph.GA↗