ORCID Profile
0000-0002-2113-4863
Current Organisations
Universidad Autónoma de Madrid
,
The University of Edinburgh
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Publisher: Oxford University Press (OUP)
Date: 20-08-2020
Abstract: Current and future cosmological surveys are targeting star-forming galaxies at z ∼ 1 with nebular emission lines. We use a state-of-the-art semi-analytical model of galaxy formation and evolution to explore the large-scale environment of star-forming emission line galaxies (ELGs). Model ELGs are selected such that they can be compared directly with the DEEP2, VVDS, eBOSS-SGC, and DESI surveys. The large-scale environment of the ELGs is classified using velocity–shear–tensor and tidal–tensor algorithms. Half of the model ELGs live in filaments and about a third in sheets. Model ELGs that reside in knots have the largest satellite fractions. We find that the shape of the mean halo occupation distribution of model ELGs varies widely for different large-scale environments. To interpret our results, we also study fixed number density s les of ELGs and galaxies selected using simpler criteria, with single cuts in stellar mass, star formation rate, and [O ii] luminosity. The fixed number density ELG selection produces s les that are close to L[O ii] and SFR-selected s les for densities above 10−4.2 h3 Mpc−3. ELGs with an extra cut in stellar mass applied to fix their number density, present differences in sheets and knots with respect to the other s les. ELGs, SFR, and L[O ii] selected s les with equal number density have similar large-scale bias but their clustering below separations of 1h−1 Mpc is different.
Publisher: Oxford University Press (OUP)
Date: 22-11-2022
Abstract: We use a set of about 300 simulated clusters from the three hundred Project to calculate their hydrostatic masses and evaluate the associated bias by comparing them with the true cluster mass. Over a redshift range from 0.07 to 1.3, we study the dependence of the hydrostatic bias on redshift, concentration, mass growth, dynamical state, mass, and halo shapes. We find almost no correlation between the bias and any of these parameters. However, there is a clear evidence that the scatter of the mass-bias distribution is larger for low-concentrated objects, high mass growth, and more generically for disturbed systems. Moreover, we carefully study the evolution of the bias of 12 clusters throughout a major-merger event. We find that the hydrostatic-mass bias follows a particular evolution track along the merger process: to an initial significant increase of the bias recorded at the begin of merger, a constant plateaus follows until the end of merge, when there is a dramatic decrease in the bias before the cluster finally become relaxed again. This large variation of the bias is in agreement with the large scatter of the hydrostatic bias for dynamical disturbed clusters. These objects should be avoided in cosmological studies because their exact relaxation phase is difficult to predict, hence their mass bias cannot be trivially accounted for.
Publisher: EDP Sciences
Date: 2022
DOI: 10.1051/EPJCONF/202225700008
Abstract: Several methods are used to evaluate, from observational data, the dynamical state of galaxy clusters. Among them, the morphological analysis of cluster images is well suited for this purpose. We report a new approach to the morphology, which consists in analytically modelling the images with a set of orthogonal functions, the Zernike polynomials (ZPs). We validated the method on mock high-resolution Compton parameter maps of synthetic galaxy clusters from T he T hree H undred project. To classify the maps for their morphology we defined a single parameter, C , by combining the contribution of some ZPs in the modelling. We verify that C is linearly correlated with a combination of common morphological parameters and also with a proper 3D dynamicalstate indicator available for the synthetic clusters we used. We also show the early results of the Zernike modelling applied on Compton parameter maps of local clusters ( z 0:1) observed by the Planck satellite. At last, we report the preliminary results of this kind of morphological analysis on mock X-ray maps of T he T hree H undred clusters.
Publisher: American Astronomical Society
Date: 10-11-2008
DOI: 10.1086/592079
Publisher: American Astronomical Society
Date: 02-2023
Abstract: We have combined X-ray observations from Chandra with Sunyaev–Zel’dovich effect data from Planck and Bolocam to measure intracluster medium pressure profiles from 0.03 R 500 ≤ R ≤ 5 R 500 for a s le of 21 low- z galaxy clusters with a median redshift of 〈 z 〉 = 0.08 and a median mass of 〈 M 500 〉 = 6.1 × 10 14 M ⊙ and a s le of 19 mid- z galaxy clusters with 〈 z 〉 = 0.50 and 〈 M 500 〉 = 10.6 × 10 14 M ⊙ . The mean scaled pressure in the low- z s le is lower at small radii and higher at large radii, a trend that is accurately reproduced in similarly selected s les from The Three Hundred simulations. This difference appears to be primarily due to dynamical state at small radii, evolution at intermediate radii, and a combination of evolution and mass dependence at large radii. Furthermore, the overall flattening of the mean scaled pressure profile in the low- z s le compared to the mid- z s le is consistent with expectations due to differences in the mass accretion rate and the fractional impact of feedback mechanisms. In agreement with previous studies, the fractional scatter about the mean scaled pressure profile reaches a minimum of ≃20% near 0.5 R 500 . This scatter is consistent between the low- z and mid- z s les at all radii, suggesting it is not strongly impacted by s le selection, and this general behavior is reproduced in The Three Hundred simulations. Finally, analytic functions that approximately describe the mass and redshift trends in mean pressure profile shape are provided.
Publisher: American Astronomical Society
Date: 25-08-2022
Abstract: Using reconstructed initial conditions in the Sloan Digital Sky Survey (SDSS) survey volume, we carry out constrained hydrodynamic simulations in three regions representing different types of the cosmic web: the Coma cluster of galaxies the SDSS Great Wall and a large low-density region at z ∼ 0.05. These simulations, which include star formation and stellar feedback but no active galactic nucleus formation and feedback, are used to investigate the properties and evolution of intergalactic and intracluster media. About half of the warm-hot intergalactic gas is associated with filaments in the local cosmic web. Gas in the outskirts of massive filaments and halos can be heated significantly by accretion shocks generated by mergers of filaments and halos, respectively, and there is a tight correlation between the gas temperature and the strength of the local tidal field. The simulations also predict some discontinuities associated with shock fronts and contact edges, which can be tested using observations of the thermal Sunyaev–Zel’dovich effect and X-rays. A large fraction of the sky is covered by Ly α and O vi absorption systems, and most of the O vi systems and low-column-density H i systems are associated with filaments in the cosmic web. The constrained simulations, which follow the formation and heating history of the observed cosmic web, provide an important avenue to interpret observational data. With full information about the origin and location of the cosmic gas to be observed, such simulations can also be used to develop observational strategies.
Publisher: Oxford University Press (OUP)
Date: 03-11-2022
Abstract: In this paper, we study the applicability of a set of supervised machine learning (ML) models specifically trained to infer observed related properties of the baryonic component (stars and gas) from a set of features of dark matter (DM)-only cluster-size haloes. The training set is built from the three hundred project that consists of a series of zoomed hydrodynamical simulations of cluster-size regions extracted from the 1 Gpc volume MultiDark DM-only simulation (MDPL2). We use as target variables a set of baryonic properties for the intracluster gas and stars derived from the hydrodynamical simulations and correlate them with the properties of the DM haloes from the MDPL2 N-body simulation. The different ML models are trained from this data base and subsequently used to infer the same baryonic properties for the whole range of cluster-size haloes identified in the MDPL2. We also test the robustness of the predictions of the models against mass resolution of the DM haloes and conclude that their inferred baryonic properties are rather insensitive to their DM properties that are resolved with almost an order of magnitude smaller number of particles. We conclude that the ML models presented in this paper can be used as an accurate and computationally efficient tool for populating cluster-size haloes with observational related baryonic properties in large volume N-body simulations making them more valuable for comparison with full sky galaxy cluster surveys at different wavelengths. We make the best ML trained model publicly available.
Publisher: Oxford University Press (OUP)
Date: 11-12-2020
Abstract: Galaxy cluster outskirts are described by complex velocity fields induced by diffuse material collapsing towards filaments, gas, and galaxies falling into clusters, and gas shock processes triggered by substructures. A simple scenario that describes the large-scale tidal fields of the cosmic web is not able to fully account for this variety, nor for the differences between gas and collisionless dark matter. We have studied the filamentary structure in zoom-in resimulations centred on 324 clusters from the threehundred project, focusing on differences between dark and baryonic matter. This paper describes the properties of filaments around clusters out to five R200, based on the diffuse filament medium where haloes had been removed. For this, we stack the remaining particles of all simulated volumes to calculate the average profiles of dark matter and gas filaments. We find that filaments increase their thickness closer to nodes and detect signatures of gas turbulence at a distance of ${\\sim}2 \\rm {{{~h^{-1}\\,{\\rm Mpc}}}}$ from the cluster. These are absent in dark matter. Both gas and dark matter collapse towards filament spines at a rate of ${\\sim}200 \\,\\rm {km ~ s^{-1}\\, h^{-1}}$. We see that gas preferentially enters the cluster as part of filaments, and leaves the cluster centre outside filaments. We further see evidence for an accretion shock just outside the cluster. For dark matter, this preference is less obvious. We argue that this difference is related to the turbulent environment. This indicates that filaments act as highways to fuel the inner regions of clusters with gas and galaxies.
Publisher: Springer Science and Business Media LLC
Date: 05-07-2021
Publisher: Oxford University Press (OUP)
Date: 22-10-2020
Abstract: We present the eddington bias corrected specific star formation rate function (sSFRF) at different stellar mass scales from a sub-s le of the Sloan Digital Sky Survey Data Release DR7 (SDSS), which is considered complete both in terms of stellar mass (M⋆) and star formation rate (SFR). The above enable us to study qualitatively and quantitatively quenching, the distribution of passive/star-forming galaxies and perform comparisons with the predictions from state-of-the-art cosmological models, within the same M⋆ and SFR limits. We find that at the low-mass end (${M_{\\star }} = 10^{9.5}\\!-\\!10^{10} \\, {\\rm M_{\\odot }}$) the sSFRF is mostly dominated by star-forming objects. However, moving to the two more massive bins (${M_{\\star }} = 10^{10}\\!-\\!10^{10.5} \\, {\\rm M_{\\odot }}$ and ${M_{\\star }} = 10^{10.5}\\!-\\!10^{11} \\, {\\rm M_{\\odot }}$) a bi-modality with two peaks emerges. One peak represents the star-forming population, while the other describes a rising passive population. The bi-modal form of the sSFRFs is not reproduced by a range of cosmological simulations (e.g. Illustris, EAGLE, Mufasa, and IllustrisTNG) which instead generate mostly the star-forming population, while a bi-modality emerges in others (e.g. L-Galaxies, Shark, and Simba). Our findings reflect the need for the employed quenching schemes in state-of-the-art models to be reconsidered, involving prescriptions that allow ‘quenched galaxies’ to retain a small level of SF activity (sSFR = ${\\rm 10^{-11} \\, }$–${\\rm 10^{-12} \\, {\\rm yr^{-1}}}$) and generate an adequate passive population/bi-modality even at intermediate masses (${M_{\\star }} = 10^{10}\\!-\\!10^{10.5} \\, {\\rm M_{\\odot }}$).
Publisher: Oxford University Press (OUP)
Date: 22-10-2020
Abstract: We compare the statistics and morphology of giant arcs in galaxy clusters using N-body and non-radiative SPH simulations within the standard cold dark matter (CDM) model and simulations where dark matter (DM) has a non-negligible probability of interaction (parametrized by its cross-section), i.e self-interacting dark matter (SIDM). We use a ray-tracing technique to produce a statistically large number of arcs around six simulated galaxy clusters at different redshifts. Since DM is more likely to interact in colliding clusters than in relaxed clusters, and this probability of interaction is largest in denser regions, we focus our analysis on radial arcs (which trace the lensing potential in the central region better than tangential arcs) in galaxy clusters that underwent (or are undergoing) a major merger. We find that SIDM produces fewer radial arcs than standard CDM but they are on average more magnified. We also appreciate differences in the arc morphology that could be used to statistically favour one model versus the other.
Publisher: Oxford University Press (OUP)
Date: 07-01-2021
Abstract: We analyse the gas content evolution of infalling haloes in cluster environments from The Three Hundred project, a collection of 324 numerically modelled galaxy clusters. The haloes in our s le were selected within 5R200 of the main cluster halo at $z$ = 0 and have total halo mass M200 ≥ 1011h−1M⊙. We track their main progenitors and study their gas evolution since their crossing into the infall region, which we define as 1–4R200. Studying the radial trends of our populations using both the full phase-space information and a line-of-sight projection, we confirm the Arthur et al. (2019) result and identify a characteristic radius around 1.7R200 in 3D and at R200 in projection at which infalling haloes lose nearly all of the gas prior their infall. Splitting the trends by subhalo status,we show that subhaloes residing in group-mass and low-mass host haloes in the infall region follow similar radial gas-loss trends as their hosts, whereas subhaloes of cluster-mass host haloes are stripped of their gas much further out. Our results show that infalling objects suffer significant gaseous disruption that correlates with time-since-infall, cluster-centric distance, and host mass, and that the gaseous disruption they experience is a combination of subhalo pre-processing and object gas depletion at a radius that behaves like an accretion shock.
Publisher: Oxford University Press (OUP)
Date: 10-02-2022
Abstract: We investigate how large-scale cosmic filaments impact the quenching of galaxies within one virial radius of 324 simulated clusters from The Three Hundred project. We track cosmic filaments with the versatile, observation-friendly program DisPerSE and identify haloes hosting galaxies with VELOCIRaptor. We find that cluster galaxies close to filaments tend to be more star forming, bluer, and contain more cold gas than their counterparts further away from filaments. This effect is recovered at all stellar masses. This is in stark contrast with galaxies residing outside of clusters, where galaxies close to filaments show clear signs of density related pre-processing. We first show that the density contrast of filaments is reduced inside the intra-cluster medium. Moreover, examination of flows around and into cluster galaxies shows that the gas flows in intra-cluster filaments are colder and tend to stream along with galaxies in their midst, partially shielding them from strangulation by the hot, dense intra-cluster medium. This also preserves accretion on to satellites and limit ram pressure.
Publisher: Oxford University Press (OUP)
Date: 03-2021
Abstract: Inferring line-of-sight distances from redshifts in and around galaxy clusters is complicated by peculiar velocities, a phenomenon known as the ‘Fingers of God’ (FoG). This presents a significant challenge for finding filaments in large observational data sets as these artificial elongations can be wrongly identified as cosmic web filaments by extraction algorithms. Upcoming targeted wide-field spectroscopic surveys of galaxy clusters and their infall regions, such as the WEAVE Wide-Field Cluster Survey, motivate our investigation of the impact of FoG on finding filaments connected to clusters. Using zoom-in resimulations of 324 massive galaxy clusters and their outskirts from the three hundred project, we test methods typically applied to large-scale spectroscopic data sets. This paper describes our investigation of whether a statistical compression of the FoG of cluster centres and galaxy groups can lead to correct filament extractions in the cluster outskirts. We find that within 5R200 (∼15 h−1 Mpc) statistically correcting for FoG elongations of virialized regions does not achieve reliable filament networks compared to reference filament networks based on true positions. This is due to the complex flowing motions of galaxies towards filaments in addition to the cluster infall, which overwhelm the signal of the filaments relative to the volume that we probe. While information from spectroscopic redshifts is still important to isolate the cluster regions, and thereby reduce background and foreground interlopers, we expect future spectroscopic surveys of galaxy cluster outskirts to rely on 2D positions of galaxies to extract cosmic filaments.
Publisher: Oxford University Press (OUP)
Date: 28-05-2021
Abstract: We report the non-thermal pressure fraction (Pnt/Ptot) obtained from a three-dimensional triaxial analysis of 16 galaxy clusters in the CLASH s le using gravitational lensing (GL) data primarily from Subaru and HST, X-ray spectroscopic imaging from Chandra, and Sunyaev–Zel’dovich effect (SZE) data from Planck and Bolocam. Our results span the approximate radial range 0.015–0.4 R200m (∼35–1000 kpc). At cluster-centric radii smaller than 0.1 R200m the ensemble average Pnt/Ptot is consistent with zero with an upper limit of 9 per cent, indicating that heating from active galactic nuclei and other relevant processes does not produce significant deviations from hydrostatic equilibrium (HSE). The ensemble average Pnt/Ptot increases outside of this radius to approximately 20 per cent at 0.4 R200m, as expected from simulations, due to newly accreted material thermalizing via a series of shocks. Also in agreement with simulations, we find significant cluster-to-cluster variation in Pnt/Ptot and little difference in the ensemble average Pnt/Ptot based on dynamical state. We conclude that on average, even for erse s les, HSE-derived masses in the very central regions of galaxy clusters require only modest corrections due to non-thermal motions.
Publisher: Oxford University Press (OUP)
Date: 07-11-2013
Publisher: Oxford University Press (OUP)
Date: 28-08-2021
Abstract: In the hierarchical scenario of structure formation, galaxy clusters are the ultimate virialized products in mass and time. Hot baryons in the intracluster medium (ICM) and cold baryons in galaxies inhabit a dark matter dominated halo. Internal processes, accretion, and mergers can perturb the equilibrium, which is established only at later times. However, the cosmic time when thermalization is effective is still to be assessed. Here, we show that massive clusters in the observed universe attained an advanced thermal equilibrium ∼1.8 Gyr ago, at redshift z = 0.14 ± 0.06, when the universe was 11.7 ± 0.7 Gyr old. Hot gas is mostly thermalized after the time when cosmic densities of matter and dark energy match. We find in a statistically nearly complete and homogeneous s le of 120 clusters from the Planck Early Sunyaev-Zel’dovich (ESZ) s le that the kinetic energy traced by the galaxy velocity dispersion is a faithful probe of the gravitational energy since a look back time of at least ∼5.4 Gyr, whereas the efficiency of hot gas in converting kinetic to thermal energy, as measured through X-ray observations in the core-excised area within r500, steadily increases with time. The evolution is detected at the ∼98 per cent probability level. Our results demonstrate that halo mass accretion history plays a larger role for cluster thermal equilibrium than radiative physics. The evolution of hot gas is strictly connected to the cosmic structure formation.
Publisher: Oxford University Press (OUP)
Date: 22-07-2011
Publisher: Oxford University Press (OUP)
Date: 06-12-2018
Publisher: Oxford University Press (OUP)
Date: 30-06-2018
Publisher: Oxford University Press (OUP)
Date: 24-06-2022
Abstract: We investigate the importance of various dynamical features in predicting the dynamical state (ds) of galaxy clusters, based on the Random Forest (RF) machine-learning approach. We use a large s le of galaxy clusters from the Three Hundred Project of hydrodynamical zoomed-in simulations, and construct dynamical features from the raw data as well as from the corresponding mock maps in the optical, X-ray, and Sunyaev–Zel’dovich (SZ) channels. Instead of relying on the impurity based feature importance of the RF algorithm, we directly use the out-of-bag (oob) scores to evaluate the importance of in idual features and different feature combinations. Among all the features studied, we find the virial ratio, η, to be the most important single feature. The features calculated directly from the simulations and in three dimensions carry more information on the ds than those constructed from the mock maps. Compared with the features based on X-ray or SZ maps, features related to the centroid positions are more important. Despite the large number of investigated features, a combination of up to three features of different types can already saturate the score of the prediction. Lastly, we show that the most sensitive feature η is strongly correlated with the well-known half-mass bias in dynamical modelling. Without a selection in ds, cluster haloes have an asymmetric distribution in η, corresponding to an overall positive half-mass bias. Our work provides a quantitative reference for selecting the best features to discriminate the ds of galaxy clusters in both simulations and observations.
Publisher: American Physical Society (APS)
Date: 09-07-2012
Publisher: American Astronomical Society
Date: 08-06-2018
Publisher: Oxford University Press (OUP)
Date: 19-03-2019
DOI: 10.1093/MNRAS/STZ797
Publisher: Oxford University Press (OUP)
Date: 30-09-2022
Abstract: The Sunyaev–Zeldovich (SZ) effect is a powerful tool in modern cosmology. With future observations promising ever improving SZ measurements, the relativistic corrections to the SZ signals from galaxy groups and clusters are increasingly relevant. As such, it is important to understand the differences between three temperature measures: (a) the average relativistic SZ (rSZ) temperature, (b) the mass-weighted temperature relevant for the thermal SZ (tSZ) effect, and (c) the X-ray spectroscopic temperature. In this work, we compare these cluster temperatures, as predicted by the Bahamas & Macsis, IllustrisTNG, Magneticum, and The Three Hundred Project simulations. Despite the wide range of simulation parameters, we find the SZ temperatures are consistent across the simulations. We estimate a $\\simeq 10{{\\ \\rm per\\ cent}}$ level correction from rSZ to clusters with Y ≃ 10−4 Mpc−2. Our analysis confirms a systematic offset between the three temperature measures with the rSZ temperature $\\simeq 20{{\\ \\rm per\\ cent}}$ larger than the other measures, and erging further at higher redshifts. We demonstrate that these measures depart from simple self-similar evolution and explore how they vary with the defined radius of haloes. We investigate how different feedback prescriptions and resolutions affect the observed temperatures, and discover the SZ temperatures are rather insensitive to these details. The agreement between simulations indicates an exciting avenue for observational and theoretical exploration, determining the extent of relativistic SZ corrections. We provide multiple simulation-based fits to the scaling relations for use in future SZ modelling.
Publisher: Springer Science and Business Media LLC
Date: 28-07-2021
Publisher: Oxford University Press (OUP)
Date: 19-05-2022
Abstract: We search for the signature of cosmological shocks in stacked gas pressure profiles of galaxy clusters using data from the South Pole Telescope (SPT). Specifically, we stack the latest Compton-y maps from the 2500 deg2 SPT-SZ survey on the locations of clusters identified in that same data set. The s le contains 516 clusters with mean mass $\\langle M_{\\rm 200m}\\rangle = 10^{14.9} \\, {\\rm M}_\\odot$ and redshift 〈z〉 = 0.55. We analyse in parallel a set of zoom-in hydrodynamical simulations from the three hundred project. The SPT-SZ data show two features: (i) a pressure deficit at R/R200m = 1.08 ± 0.09, measured at 3.1σ significance and not observed in the simulations, and (ii) a sharp decrease in pressure at R/R200m = 4.58 ± 1.24 at 2.0σ significance. The pressure deficit is qualitatively consistent with a shock-induced thermal non-equilibrium between electrons and ions, and the second feature is consistent with accretion shocks seen in previous studies. We split the cluster s le by redshift and mass, and find both features exist in all cases. There are also no significant differences in features along and across the cluster major axis, whose orientation roughly points towards filamentary structure. As a consistency test, we also analyse clusters from the Planck and Atacama Cosmology Telescope Polarimeter surveys and find quantitatively similar features in the pressure profiles. Finally, we compare the accretion shock radius ($R_{\\rm sh,\\, acc}$) with existing measurements of the splashback radius (Rsp) for SPT-SZ and constrain the lower limit of the ratio, $R_{\\rm sh,\\, acc}/R_{\\rm sp}\\gt 2.16 \\pm 0.59$.
Publisher: EDP Sciences
Date: 2022
DOI: 10.1051/EPJCONF/202225700018
Abstract: The Planck Collaboration has shown that the number of clusters as a function of their mass and redshift is an extremely powerful tool for cosmological analyses. However, the true cluster mass is not directly measurable. Among the possible approaches, clusters mass could be related to different observables via self similar scaling law. These observables are related to the baryonic components of which a cluster is composed. However, the theoretical relations that allow the use of these proxies often are affected by observational and physical biases, which impacts on the determination of the cluster mass. Fortunately, cosmological simulations are an extremely powerful tool to assess these problems. We present our calibration of the scaling relation between mass and velocity dispersion of galaxy members from the study of the simulated clusters of T he T hree H undred project with mass above 10 13 M ⊙ . In order to investigate the presence of a redshift dependence, we analyzed 16 different redshifts between z = 0 and z = 2. Finally, we investigated the impact of different AGN feedback models.
Publisher: Oxford University Press (OUP)
Date: 19-08-2020
Abstract: Protoclusters, which will yield galaxy clusters at lower redshift, can provide valuable information on the formation of galaxy clusters. However, identifying progenitors of galaxy clusters in observations is not an easy task, especially at high redshift. Different priors have been used to estimate the overdense regions that are thought to mark the locations of protoclusters. In this paper, we use mimicked Ly α-emitting galaxies at z = 5.7 to identify protoclusters in the MultiDark galaxies, which are populated by applying three different semi-analytic models to the $1\\, h^{-1}\\, {\\rm Gpc}$ MultiDark Planck2 simulation. To compare with observational results, we extend the criterion 1 (a Ly α luminosity limited s le) to criterion 2 (a match to the observed mean galaxy number density). To further statistically study the finding efficiency of this method, we enlarge the identified protocluster s le (criterion 3) to about 3500 at z = 5.7 and study their final mass distribution. The number of overdense regions and their selection probability depends on the semi-analytic models and strongly on the three selection criteria (partly by design). The protoclusters identified with criterion 1 are associated with a typical final cluster mass of $2.82\\pm 0.92 \\times 10^{15} \\, \\rm {M_{\\odot }}$, which is in agreement with the prediction (within ±1σ) of an observed massive protocluster at z = 5.7. Identifying more protoclusters allows us to investigate the efficiency of this method, which is more suitable for identifying the most massive clusters: completeness ($\\mathbb {C}$) drops rapidly with decreasing halo mass. We further find that it is hard to have a high purity ($\\mathbb {P}$) and completeness simultaneously.
Publisher: Oxford University Press (OUP)
Date: 06-09-2022
Abstract: The relation between the integrated thermal Sunyaev–Zeldovich (tSZ) y-decrement versus halo mass (Y–M) can potentially constrain galaxy formation models, if theoretical and observational systematics can be properly assessed. We investigate the Y–M relation in the simba and IllustrisTNG-100 cosmological hydrodynamic simulations, quantifying the effects of feedback, line-of-sight projection, and beam convolution. We find that simba’s active galactic nucleus (AGN) jet feedback generates strong deviations from self-similar expectations for the Y–M relation, especially at $M_{\\rm 500}\\lesssim10^{13}M_\\odot$. In simba, this is driven by suppressed in-halo y contributions owing to lowered halo baryon fractions. IllustrisTNG results more closely resemble simba without jets. Projections of line-of-sight structures weaken these model differences slightly, but they remain significant – particularly at group and lower halo masses. In contrast, beam smearing at Planck resolution makes the models indistinguishable, and both models appear to agree well with Planck data down to the lowest masses probed. We show that the arcminute resolution expected from forthcoming facilities would retain the differences between model predictions, and thereby provide strong constraints on AGN feedback.
Publisher: Oxford University Press (OUP)
Date: 31-01-2022
Abstract: Using the data set of the three hundred project, i.e. a suite of 324 hydrodynamical resimulations of cluster-sized haloes, we study galaxy cluster mergers and their effect on colour and luminosity changes of their brightest cluster galaxies (BCG). We track the main progenitor of each halo at z = 0 and search for merger situations based on its mass accretion history, defining mergers as very rapid increases in the halo mass. Based upon the evolution of the dynamical state of the cluster we define a pre- and post-merger phase. We create a list of all these events and statistically study their mass ratio and time-scales, with the former verifying that all instances are in fact major mergers. By comparing to a control s le of clusters without mergers, we study the effect mergers have on the stellar component of the BCG. Analysing the mass, age, and metallicity of the BCG stellar particles, we find that the stellar content of BCGs grows significantly during mergers and, even though the main growth mechanism is the accretion of older stars, there is even a burst in star formation induced by the merger. In our simulations, BCGs in mergers form in median around 70 per cent more stars than those normally growing, although this depends on the radius considered for defining the BCG. Regarding observable properties, we see an increase in SDSS-u luminosity of 20 per cent during mergers, accompanied by a slightly slower increase of the galaxy g − r colour as compared to the control s le.
Publisher: Oxford University Press (OUP)
Date: 20-05-2020
Abstract: Using the catalogues of galaxy clusters from The Three Hundred project, modelled with both hydrodynamic simulations (gadget-x and gadget-music), and semi-analytical models (SAMs), we study the scatter and self-similarity of the profiles and distributions of the baryonic components of the clusters: the stellar and gas mass, metallicity, the stellar age, gas temperature, and the (specific) star formation rate. Through comparisons with observational results, we find that the shape and the scatter of the gas density profiles matches well the observed trends including the reduced scatter at large radii which is a signature of self-similarity suggested in previous studies. One of our simulated sets, gadget-x, reproduces well the shape of the observed temperature profile, while gadget-music has a higher and flatter profile in the cluster centre and a lower and steeper profile at large radii. The gas metallicity profiles from both simulation sets, despite following the observed trend, have a relatively lower normalization. The cumulative stellar density profiles from SAMs are in better agreement with the observed result than both hydrodynamic simulations which show relatively higher profiles. The scatter in these physical profiles, especially in the cluster centre region, shows a dependence on the cluster dynamical state and on the cool-core/non-cool-core dichotomy. The stellar age, metallicity, and (s)SFR show very large scatter, which are then presented in 2D maps. We also do not find any clear radial dependence of these properties. However, the brightest central galaxies have distinguishable features compared to the properties of the satellite galaxies.
Publisher: EDP Sciences
Date: 08-2021
DOI: 10.1051/0004-6361/202038425
Abstract: Using 324 numerically modelled galaxy clusters as provided by T HE T HREE H UNDRED project, we study the evolution of the kinematic properties of the stellar component of haloes on first infall. We selected objects with M star 5 × 10 10 h −1 M ⊙ within 3 R 200 of the main cluster halo at z = 0 and followed their progenitors. We find that although haloes are stripped of their dark matter and gas after entering the main cluster halo, there is practically no change in their stellar kinematics. For the vast majority of our ‘galaxies’ – defined as the central stellar component found within the haloes that form our s le – their kinematic properties, as described by the fraction of ordered rotation, and their position in the specific stellar angular momentum−stellar mass plane j star − M star are mostly unchanged by the influence of the central host cluster. However, for a small number of infalling galaxies, stellar mergers and encounters with remnant stellar cores close to the centre of the main cluster, particularly during pericentre passage, are able to spin up their stellar component by z = 0.
Publisher: Oxford University Press (OUP)
Date: 20-12-2017
Publisher: American Astronomical Society
Date: 30-11-2018
Publisher: Oxford University Press (OUP)
Date: 21-10-2023
Publisher: InTech
Date: 07-06-2017
DOI: 10.5772/68116
Publisher: American Astronomical Society
Date: 12-2022
Abstract: We investigate the influence of active galactic nucleus (AGN) feedback on the galaxy cold gas content and its connection to galaxy quenching in three hydrodynamical simulations of Illustris, IllustrisTNG, and SIMBA. By comparing to the observed atomic and molecular neutral hydrogen measurements for central galaxies, we find that Illustris overpredicts the cold gas masses in star-forming galaxies and significantly underpredicts them for quenched galaxies. IllustrisTNG performs better in this comparison than Illustris, but quenched galaxies retain too much cold gas compared with observations. SIMBA shows good agreement with observations, by depleting the global cold gas reservoir for quenched galaxies. We find that the discrepancies in IllustrisTNG are caused by its weak kinetic AGN feedback that only redistributes the cold gas from the inner disks to the outer regions and reduces the inner cold gas densities. It agrees with observations much better when only the cold gas within the stellar disk is considered to infer the star formation rates. From dependences of the cold gas reservoir on the black hole mass and Eddington ratio, we find that the cumulative energy release during the black hole growth is the dominant reason for the cold gas depletion and thus the galaxy quenching. We further measure the central stellar surface density within 1 kpc (Σ 1 ) for the high-resolution run of IllustrisTNG and find a tight correlation between Σ 1 and black hole mass. It suggests that the observed decreasing trend of cold gas mass with Σ 1 is also a reflection of the black hole growth.
Publisher: American Physical Society (APS)
Date: 26-07-2011
Publisher: Oxford University Press (OUP)
Date: 18-05-2023
Abstract: The distribution of baryons provides a significant way to understand the formation of galaxy clusters by revealing the details of its internal structure and changes over time. In this paper, we present theoretical studies on the scaled profiles of physical properties associated with the baryonic components, including gas density, temperature, metallicity, pressure and entropy as well as stellar mass, metallicity and satellite galaxy number density in galaxy clusters from z = 4 to z = 0 by tracking their progenitors. These mass-complete simulated galaxy clusters are coming from The Three Hundred with two runs: Gizmo-SIMBA and Gadget-X. Through comparisons between the two simulations, and with observed profiles that are generally available at low redshift, we find that (1) the agreements between the two runs and observations are mostly at outer radii r ≳ 0.3r500, in line with the self-similarity assumption. While Gadget-X shows better agreements with the observed gas profiles in the central regions compared to Gizmo-SIMBA (2) the evolution trends are generally consistent between the two simulations with slightly better consistency at outer radii. In detail, the gas density profile shows less discrepancy than the temperature and entropy profiles at high redshift. The differences in the cluster centre and gas properties imply different behaviours of the AGN models between Gadget-X and Gizmo-SIMBA, with the latter, maybe too strong for this cluster simulation. The high-redshift difference may be caused by the star formation and feedback models or hydrodynamics treatment, which requires observation constraints and understanding.
Publisher: EDP Sciences
Date: 2022
DOI: 10.1051/EPJCONF/202225700011
Abstract: The role of baryon models in hydrodynamic simulations is still unclear. Future surveys that use cluster statistics to precisely constrain cosmological models require a better understanding of the baryonic effects. Using the hydro-simulated galaxy clusters from different baryon models (Gadget-MUSIC, Gadget-X and Gizmo-SIMBA) from the THREEHUNDRED project, we can address this question into more details. We find that the galaxy cluster mass change due to different baryon models is at a few per cent level. However, the mass changes can be positive or negative depending on the baryon models. Such a small mass change leaves a weak influence (slightly larger compared to the mass changes) on both the cumulative halo numbers and the differential halo mass function (HMF) above the mass completeness. Similarly to to the halo mass change, the halo mass or the HMF can be increased or decreased with respect to the dark-matter-only (DMO) run depending on the baryon models.
Publisher: American Astronomical Society
Date: 19-01-2018
Publisher: EDP Sciences
Date: 02-2020
DOI: 10.1051/0004-6361/201936742
Abstract: Accurate and precise measurement of the masses of galaxy clusters is key to deriving robust constraints on cosmological parameters. However, increasing evidence from observations confirms that X-ray masses obtained under the assumption of hydrostatic equilibrium might be underestimated, as previously predicted by cosmological simulations. We analyze more than 300 simulated massive clusters from the Three Hundred Project, and investigate the connection between mass bias and several diagnostics extracted from synthetic X-ray images of these simulated clusters. We find that the azimuthal scatter measured in 12 sectors of the X-ray flux maps is a statistically significant indication of the presence of an intrinsic (i.e., 3D) clumpy gas distribution. We verify that a robust correction to the hydrostatic mass bias can be inferred when estimates of the gas inhomogeneity from X-ray maps (such as the azimuthal scatter or the gas ellipticity) are combined with the asymptotic external slope of the gas density or pressure profiles, which can be respectively derived from X-ray and millimeter (Sunyaev-Zeldovich effect) observations. We also obtain that mass measurements based on either gas density and temperature or gas density and pressure result in similar distributions of the mass bias. In both cases, we provide corrections that help reduce both the dispersion and skewness of the mass bias distribution. These are effective even when irregular clusters are included leading to interesting implications for the modeling and correction of hydrostatic mass bias in cosmological analyses of current and future X-ray and SZ cluster surveys.
Publisher: EDP Sciences
Date: 2022
DOI: 10.1051/EPJCONF/202225700013
Abstract: Galaxy cluster masses can be inferred indirectly using measurements from X-ray band, Sunyaev-Zeldovich (SZ) effect signal or optical observations. Unfortunately, all of them are affected by some bias. Alternatively, we provide an independent estimation of the cluster masses from the Planck PSZ2 catalog of galaxy clusters using a machine-learning method. We train a Convolutional Neural Network (CNN) model with the mock SZ observations from T he T hree H undred (the300) hydrodynamic simulations to infer the cluster masses from the real maps of the Planck clusters. The advantage of the CNN is that no assumption on a priory symmetry in the cluster’s gas distribution or no additional hypothesis about the cluster physical state are made. We compare the cluster masses from the CNN model with those derived by Planck and conclude that the presence of a mass bias is compatible with the simulation results.
Publisher: Oxford University Press (OUP)
Date: 31-12-2015
Publisher: Oxford University Press (OUP)
Date: 15-11-2017
Publisher: American Astronomical Society
Date: 28-06-2022
Abstract: Using the extended halo-based group finder developed by Yang et al., which is able to deal with galaxies via spectroscopic and photometric redshifts simultaneously, we construct galaxy group and candidate protocluster catalogs in a wide redshift range (0 z 6) from the joint CFHT Large Area U -band Deep Survey and Hyper Suprime-Cam Subaru Strategic Program deep data set. Based on a selection of 5,607,052 galaxies with i -band magnitude m i 26 and a sky coverage of 34.41 deg 2 , we identify a total of 2,232,134 groups, of which 402,947 groups have at least three member galaxies. We have visually checked and discussed the general properties of these richest groups at redshift z 2.0. By checking the galaxy number distributions within a 5–7 h −1 Mpc projected separation and a redshift difference Δ z ≤ 0.1 around those richest groups at redshift z 2, we identify lists of 761, 343, and 43 protocluster candidates in the redshift bins 2 ≤ z 3, 3 ≤ z 4, and z ≥ 4, respectively. In general, these catalogs of galaxy groups and protocluster candidates will provide useful environmental information in probing galaxy evolution along cosmic time.
Publisher: Oxford University Press (OUP)
Date: 2019
DOI: 10.1093/MNRAS/STZ565
Publisher: Oxford University Press (OUP)
Date: 14-11-2019
Abstract: Galaxy cluster outskirts mark the transition region from the mildly non-linear cosmic web to the highly non-linear, virialised, cluster interior. It is in this transition region that the intra-cluster medium (ICM) begins to influence the properties of accreting galaxies and groups, as ram pressure impacts a galaxy’s cold gas content and subsequent star formation rate. Conversely, the thermodynamical properties of the ICM in this transition region should also feel the influence of accreting substructure (i.e. galaxies and groups), whose passage can drive shocks. In this paper, we use a suite of cosmological hydrodynamical zoom simulations of a single galaxy cluster, drawn from the nIFTy comparison project, to study how the dynamics of substructure accreted from the cosmic web influences the thermodynamical properties of the ICM in the cluster’s outskirts. We demonstrate how features evident in radial profiles of the ICM (e.g. gas density and temperature) can be linked to strong shocks, transient and short-lived in nature, driven by the passage of substructure. The range of astrophysical codes and galaxy formation models in our comparison are broadly consistent in their predictions (e.g. agreeing when and where shocks occur, but differing in how strong shocks will be) this is as we would expect of a process driven by large-scale gravitational dynamics and strong, inefficently radiating, shocks. This suggests that mapping such shock structures in the ICM in a cluster’s outskirts (via e.g. radio synchrotron emission) could provide a complementary measure of its recent merger and accretion history.
Publisher: Oxford University Press (OUP)
Date: 10-2013
Publisher: Springer Science and Business Media LLC
Date: 17-10-2022
Publisher: American Physical Society (APS)
Date: 25-05-2010
Publisher: American Astronomical Society
Date: 23-05-2017
Publisher: Oxford University Press (OUP)
Date: 29-09-2022
Abstract: Next-generation wide-field spectroscopic surveys will observe the infall regions around large numbers of galaxy clusters with high s ling rates for the first time. Here, we assess the feasibility of extracting the large-scale cosmic web around clusters using forthcoming observations, given realistic observational constraints. We use a s le of 324 hydrodynamic zoom-in simulations of massive galaxy clusters from TheThreeHundred project to create a mock-observational catalogue spanning 5R200 around 160 analogue clusters. These analogues are matched in mass to the 16 clusters targetted by the forthcoming WEAVE Wide-Field Cluster Survey (WWFCS). We consider the effects of the fibre allocation algorithm on our s ling completeness and find that we successfully allocate targets to 81.7 ${\\rm {per \\,cent}}\\, \\pm$ 1.3 of the members in the cluster outskirts. We next test the robustness of the filament extraction algorithm by using a metric, Dskel, which quantifies the distance to the filament spine. We find that the median positional offset between reference and recovered filament networks is Dskel = 0.13 ± 0.02 Mpc, much smaller than the typical filament radius of ∼ 1 Mpc. Cluster connectivity of the recovered network is not substantially affected. Our findings give confidence that the WWFCS will be able to reliably trace cosmic web filaments in the vicinity around massive clusters, forming the basis of environmental studies into the effects of pre-processing on galaxy evolution.
Publisher: Oxford University Press (OUP)
Date: 02-02-2023
Abstract: We develop a machine learning algorithm to infer the three-dimensional cumulative radial profiles of total and gas masses in galaxy clusters from thermal Sunyaev–Zel’dovich effect maps. We generate around 73 000 mock images along various lines of sight using 2522 simulated clusters from the three hundred project at redshift z & 0.12 and train a model that combines an auto-encoder and a random forest. Without making any prior assumptions about the hydrostatic equilibrium of the clusters, the model is capable of reconstructing the total mass profile as well as the gas mass profile, which is responsible for the Sunyaev–Zel’dovich effect. We show that the recovered profiles are unbiased with a scatter of about 10 per cent, slightly increasing towards the core and the outskirts of the cluster. We selected clusters in the mass range of $10^{13.5} \\le M_{200} /({{\\, h^{-1}\\,{\\rm {{\\rm M}_{\\odot }}}}}) \\le 10^{15.5}$, spanning different dynamical states, from relaxed to disturbed haloes. We verify that both the accuracy and precision of this method show a slight dependence on the dynamical state, but not on the cluster mass. To further verify the consistency of our model, we fit the inferred total mass profiles with a Navarro–Frenk–White model and contrast the concentration values with those of the true profiles. We note that the inferred profiles are unbiased for higher concentration values, reproducing a trustworthy mass–concentration relation. The comparison with a widely used mass estimation technique, such as hydrostatic equilibrium, demonstrates that our method recovers the total mass that is not biased by non-thermal motions of the gas.
Publisher: Oxford University Press (OUP)
Date: 14-05-2022
Abstract: We introduce gizmo-simba, a new suite of galaxy cluster simulations within The Three Hundred project. The Three Hundred consists of zoom re-simulations of 324 clusters with $M_{200}\\gtrsim 10^{14.8}\\, \\mathrm{M}_\\odot$ drawn from the MultiDark-Planck N-body simulation, run using several hydrodynamic and semi-analytical codes. The gizmo-simba suite adds a state-of-the-art galaxy formation model based on the highly successful Simba simulation, mildly re-calibrated to match $z$ = 0 cluster stellar properties. Comparing to The Three Hundred zooms run with gadget-x, we find intrinsic differences in the evolution of the stellar and gas mass fractions, BCG ages, and galaxy colour–magnitude diagrams, with gizmo-simba generally providing a good match to available data at $z$ ≈ 0. gizmo-simba’s unique black hole growth and feedback model yields agreement with the observed BH scaling relations at the intermediate-mass range and predicts a slightly different slope at high masses where few observations currently lie. Gizmo-Simba provides a new and novel platform to elucidate the co-evolution of galaxies, gas, and black holes within the densest cosmic environments.
Publisher: Oxford University Press (OUP)
Date: 10-08-2022
Abstract: Using the state-of-the-art suite of hydrodynamic simulations Simba, as well as its dark-matter-only counterpart, we study the impact of the presence of baryons and of different stellar/AGN feedback mechanisms on large-scale structure, halo density profiles, and on the abundance of different baryonic phases within haloes and in the intergalactic medium (IGM). The unified picture that emerges from our analysis is that the main physical drivers shaping the distribution of matter at all scales are star formation-driven galactic outflows at z & 2 for lower mass haloes and AGN jets at z & 2 in higher mass haloes. Feedback suppresses the baryon mass function with time relative to the halo mass function, and it even impacts the halo mass function itself at the ∼20 per cent level, particularly evacuating the centres and enhancing dark matter just outside haloes. At early epochs baryons pile up in the centres of haloes, but by late epochs and particularly in massive systems gas has mostly been evacuated from within the inner halo. AGN jets are so efficient at such evacuation that at low redshifts the baryon fraction within ∼1012–1013 M⊙ haloes is only 25 per cent of the cosmic baryon fraction, mostly in stars. The baryon fraction enclosed in a sphere around such haloes approaches the cosmic value Ωb/Ωm only at 10–20 virial radii. As a result, 87 per cent of the baryonic mass in the Universe lies in the IGM at z = 0, with 67 per cent being in the form of warm-hot IGM (T & 105K).
Publisher: Oxford University Press (OUP)
Date: 03-10-2022
Abstract: Galaxy clusters grow by accreting galaxies as in idual objects, or as members of a galaxy group. These groups can strongly impact galaxy evolution, stripping the gas from galaxies, and enhancing the rate of galaxy mergers. However, it is not clear how the dynamics and structure of groups are affected when they interact with a large cluster, or whether all group members necessarily experience the same evolutionary processes. Using data from The Three Hundred project, a suite of 324 hydrodynamical resimulations of large galaxy clusters, we study the properties of 1340 groups passing through a cluster. We find that half of group galaxies become gravitationally unbound from the group by the first pericentre, typically just 0.5–1 Gyr after cluster entry. Most groups quickly mix with the cluster satellite population only $8{{\\ \\rm per\\ cent}}$ of infalling group haloes later leave the cluster, although for nearly half of these, all of their galaxies have become unbound, tidally disrupted or merged into the central by this stage. The position of galaxies in group-centric phase space is also important – only galaxies near the centre of a group (r ≲ 0.7R200) remain bound once a group is inside a cluster, and slow-moving galaxies in the group centre are likely to be tidally disrupted, or merge with another galaxy. This work will help future observational studies to constrain the environmental histories of group galaxies. For ex le, groups observed inside or nearby to clusters have likely approached very recently, meaning that their galaxies will not have experienced a cluster environment before.
Publisher: Oxford University Press (OUP)
Date: 11-04-2022
Abstract: Galaxy clusters have a triaxial matter distribution. The weak-lensing signal, an important part in cosmological studies, measures the projected mass of all matter along the line of sight, and therefore changes with the orientation of the cluster. Studies suggest that the shape of the brightest cluster galaxy (BCG) in the centre of the cluster traces the underlying halo shape, enabling a method to account for projection effects. We use 324 simulated clusters at four redshifts between 0.1 and 0.6 from ‘The Three Hundred Project’ to quantify correlations between the orientation and shape of the BCG and the halo. We find that haloes and their embedded BCGs are aligned, with an average ∼20 degree angle between their major axes. The bias in weak lensing cluster mass estimates correlates with the orientation of both the halo and the BCG. Mimicking observations, we compute the projected shape of the BCG, as a measure of the BCG orientation, and find that it is most strongly correlated to the weak-lensing mass for relaxed clusters. We also test a 2D cluster relaxation proxy measured from BCG mass isocontours. The concentration of stellar mass in the projected BCG core compared to the total stellar mass provides an alternative proxy for the BCG orientation. We find that the concentration does not correlate to the weak-lensing mass bias, but does correlate with the true halo mass. These results indicate that the BCG shape and orientation for large s les of relaxed clusters can provide information to improve weak-lensing mass estimates.
Publisher: Oxford University Press (OUP)
Date: 05-2012
Publisher: Oxford University Press (OUP)
Date: 04-02-2021
Abstract: Clusters of galaxies are useful tools to constrain cosmological parameters, only if their masses can be correctly inferred from observations. In particular, X-ray and Sunyaev–Zeldovich (SZ) effect observations can be used to derive masses within the framework of the hydrostatic equilibrium. Therefore, it is crucial to have a good control of the possible mass biases that can be introduced when this hypothesis is not valid. In this work, we analysed a set of 260 synthetic clusters from the MUSIC simulation project at redshifts 0 ≤ z ≤ 0.82. We estimate the hydrostatic mass of the MUSIC clusters from X-ray only (temperature and density) and from X-ray and SZ (density and pressure). Then, we compare them with the true 3D dynamical mass. The biases are of the order of 20 per cent. We find that using the temperature instead of the pressure leads to a smaller bias, although the two values are compatible within 1σ. Non-thermal contributions to the total pressure support, arising from bulk motion and turbulence of the gas, are also computed and show that they are sufficient to account for this bias. We also present a study of the correlation between the mass bias and the dynamical state of the clusters. A clear correlation is shown between the relaxation state of the clusters and the bias factor. We applied the same analysis on a subs le of 32 objects, already selected for supporting the NIKA2 SZ Large Program.
Publisher: Oxford University Press (OUP)
Date: 27-06-2012
Publisher: EDP Sciences
Date: 2022
DOI: 10.1051/EPJCONF/202225700020
Abstract: The assumption of Hydrostatic equilibrium (HE) is often used in observations to estimate galaxy clusters masses. We use a set of almost 300 simulated clusters from T he T hree H undred Project, to estimate the cluster HE mass and the bias deriving from it. We study the dependence of the bias on several dynamical state indicators across a redshift range from 0.07 to 1.3, finding no dependence between them. Moreover, we focus our attention on the evolution of the HE bias during the merger phase, where the bias even reaches negative values due to an overestimation of the mass with HE.
Publisher: Oxford University Press (OUP)
Date: 03-08-2018
Publisher: Oxford University Press (OUP)
Date: 08-2022
Abstract: We introduce a new parameter λDS to quantify the dynamical state of galaxy clusters and test it using simulations from The Three Hundred cluster zoom suite. λDS is a combination of three previously used dynamical state measures, namely virial ratio, centre of mass offset, and substructure mass fraction, crafted to assume a double-Gaussian distribution, thereby yielding a natural ision between relaxed and unrelaxed clusters where the Gaussians cross. Using dark matter-only simulations, we identify the optimal separator to be λDS = 3.424. We test this same criterion on two sets of fully hydrodynamical The Three Hundred runs (Gadget-X and GIZMO-SIMBA), and find only a weak dependence on the input baryonic physics. We correlate the evolution of λDS with the mass accretion history and find that halo mass changes of $\\frac{\\Delta M_{200}}{M_{200}} \\lesssim 0.12$ do not typically alter the dynamical state. We examine the relaxation period, defined as the time taken to return to relaxation after becoming disturbed, and find a correlation between this relaxation period and the strength of halo mass change $\\frac{\\Delta M_{200}}{M_{200}}$. By fitting this correlation, we show that the relaxation period can be estimated from $\\frac{\\Delta M_{200}}{M_{200}}$ (even for multiple mass accretion events) with good accuracy.
Publisher: Oxford University Press (OUP)
Date: 12-05-2014
DOI: 10.1093/MNRAS/STU673
Publisher: Oxford University Press (OUP)
Date: 11-05-2023
Abstract: Upcoming advances in galaxy surveys and cosmic microwave background data will enable measurements of the anisotropic distribution of diffuse gas in filaments and superclusters at redshift z = 1 and beyond, observed through the thermal Sunyaev–Zel’dovich (tSZ) effect. These measurements will help distinguish between different astrophysical feedback models, account for baryons that appear to be ‘missing’ from the cosmic census, and present opportunities for using locally anisotropic tSZ statistics as cosmological probes. This study seeks to guide such future measurements by analysing whether diffuse intergalactic gas is a major contributor to anisotropic tSZ signal in The Three Hundred Gizmo-Simba hydrodynamic simulations. We apply multiple different halo boundary and temperature criteria to ide concentrated from diffuse gas at z = 1, then create mock Compton- y maps for the separated components. The maps from 98 simulation snapshots are centred on massive galaxy clusters, oriented by the most prominent filament axis in the galaxy distribution, and stacked. Results vary significantly depending on the definition used for diffuse gas, indicating that assumptions should be clearly defined when claiming observations of the warm-hot intergalactic medium. In all cases, the diffuse gas is important, contributing 25–60 per cent of the tSZ signal in the far field (& h−1 comoving Mpc) from the stacked clusters. The gas 1–2 virial radii from halo centres is especially key. Oriented stacking and environmental selections help to lify the signal from the warm-hot intergalactic medium, which is aligned but less concentrated along the filament axis than the hot halo gas.
Publisher: Oxford University Press (OUP)
Date: 21-12-2021
Abstract: Galaxy cluster masses, rich with cosmological information, can be estimated from internal dark matter (DM) velocity dispersions, which in turn can be observationally inferred from satellite galaxy velocities. However, galaxies are biased tracers of the DM, and the bias can vary over host halo and galaxy properties as well as time. We precisely calibrate the velocity bias, bv – defined as the ratio of galaxy and DM velocity dispersions – as a function of redshift, host halo mass, and galaxy stellar mass threshold ($M_{\\rm \\star , sat}$), for massive haloes ($M_{\\rm 200c}\\gt 10^{13.5} \\, {\\rm M}_\\odot$) from five cosmological simulations: IllustrisTNG, Magneticum, Bahamas + Macsis, The Three Hundred Project, and MultiDark Planck-2. We first compare scaling relations for galaxy and DM velocity dispersion across simulations the former is estimated using a new ensemble velocity likelihood method that is unbiased for low galaxy counts per halo, while the latter uses a local linear regression. The simulations show consistent trends of bv increasing with M200c and decreasing with redshift and $M_{\\rm \\star , sat}$. The ensemble-estimated theoretical uncertainty in bv is 2–3 per cent, but becomes percent-level when considering only the three highest resolution simulations. We update the mass–richness normalization for an SDSS redMaPPer cluster s le, and find our improved bv estimates reduce the normalization uncertainty from 22 to 8 per cent, demonstrating that dynamical mass estimation is competitive with weak lensing mass estimation. We discuss necessary steps for further improving this precision. Our estimates for $b_v(M_{\\rm 200c}, M_{\\rm \\star , sat}, z)$ are made publicly available.
Publisher: Oxford University Press (OUP)
Date: 18-12-2020
Abstract: The knowledge of the dynamical state of galaxy clusters allows to alleviate systematics when observational data from these objects are applied in cosmological studies. Evidence of correlation between the state and the morphology of the clusters is well studied. The morphology can be inferred by images of the surface brightness in the X-ray band and of the thermal component of the Sunyaev–Zel’dovich (tSZ) effect in the millimetre range. For this purpose, we apply, for the first time, the Zernike polynomial decomposition, a common analytical approach mostly used in adaptive optics to recover aberrated radiation wavefronts at the telescopes pupil plane. With this novel way, we expect to correctly infer the morphology of clusters and so possibly their dynamical state. To verify the reliability of this new approach, we use more than 300 synthetic clusters selected in the three hundred project at different redshifts ranging from 0 up to 1.03. Mock maps of the tSZ, quantified with the Compton parameter, y-maps, are modelled with Zernike polynomials inside R500, the cluster reference radius. We verify that it is possible to discriminate the morphology of each cluster by estimating the contribution of the different polynomials to the fit of the map. The results of this new method are correlated with those of a previous analysis made on the same catalogue, using two parameters that combine either morphological or dynamical-state probes. We underline that instrumental angular resolution of the maps has an impact mainly when we extend this approach to high-redshift clusters.
Publisher: Oxford University Press (OUP)
Date: 21-01-2019
DOI: 10.1093/MNRAS/STZ212
Publisher: American Astronomical Society
Date: 03-01-2018
Publisher: IOP Publishing
Date: 05-2019
DOI: 10.1088/1742-6596/1226/1/012003
Abstract: The Sunyaev-Zel’dovich effect in galaxy clusters is a unique probe for studying astrophysics and cosmology. We propose in this work its application for the detection of possible coherent rotational motions in the hot intra-cluster medium. We select a s le of massive, relaxed and rotating galaxy clusters from Marenostrum-mUltidark SImulations of galaxy Clusters (MUSIC), and we produce mock maps of the temperature distortion produced by the kinetic Sunyaev–Zel’dovich effect by exploring six different lines of sight, in the best observational condition. These maps are compared with the expected signal computed from a suitable theoretical model in two cases: ( i ) focusing only on the contribution from the rotation, and ( ii ) accounting also for the cluster bulk motion. We find that the parameters of the model assumed for the radial profile of the rotational velocity, averaged over the considered lines of sight, are in agreement within two standard deviations at most with independent estimates from the simulation data, without being significantly affected by the presence of the cluster bulk term. The litude of the rotational signal is, on average, of the order of 23 per cent of the total signal accounting also for the cluster bulk motion, and its values are consistent with the literature. The projected bulk velocity of the cluster is also recovered at the different lines of sight, with values in agreement with the simulation data.
Publisher: American Astronomical Society
Date: 13-04-2015
Publisher: Oxford University Press (OUP)
Date: 21-05-2020
Abstract: Using 324 numerically modelled galaxy clusters, we investigate the radial and galaxy–halo alignment of dark matter subhaloes and satellite galaxies orbiting within and around them. We find that radial alignment depends on distance to the centre of the galaxy cluster but appears independent of the dynamical state of the central host cluster. Furthermore, we cannot find a relation between radial alignment of the halo or galaxy shape with its own mass. We report that backsplash galaxies, i.e. objects that have already passed through the cluster radius but are now located in the outskirts, show a stronger radial alignment than infalling objects. We further find that there exists a population of well radially aligned objects passing very close to the central cluster’s centre that were found to be on highly radial orbit.
Publisher: Oxford University Press (OUP)
Date: 06-10-2016
Publisher: Oxford University Press (OUP)
Date: 12-09-2017
Publisher: Oxford University Press (OUP)
Date: 13-07-2022
Abstract: The star formation history (SFH) of galaxies is critical for understanding galaxy evolution. Hydrodynamical simulations enable us to precisely reconstruct the SFH of galaxies and establish a link to the underlying physical processes. In this work, we present a model to describe in idual galaxies’ SFHs from three simulations: TheThreeHundred, Illustris-1, and TNG100-1. This model ides the galaxy SFH into two distinct components: the ‘main sequence’ and the ‘variation’. The ‘main sequence’ part is generated by tracing the history of the SFR − M* main sequence of galaxies across time. The ‘variation’ part consists of the scatter around the main sequence, which is reproduced by fractional Brownian motions. We find that: (1) the evolution of the main sequence varies between simulations (2) fractional Brownian motions can reproduce many features of SFHs however, discrepancies still exist and (3) the variations and mass-loss rate are crucial for reconstructing the SFHs of the simulations. This model provides a fair description of the SFHs in simulations. On the other hand, by correlating the fractional Brownian motion model to simulation data, we provide a ’standard’ against which to compare simulations.
Publisher: Oxford University Press (OUP)
Date: 03-02-2020
Abstract: In the outer regions of a galaxy cluster, galaxies either may be falling into the cluster for the first time or have already passed through the cluster centre at some point in their past. To investigate these two distinct populations, we utilize TheThreeHundred project, a suite of 324 hydrodynamical resimulations of galaxy clusters. In particular, we study the ‘backsplash population’ of galaxies: those that have passed within R200 of the cluster centre at some time in their history, but are now outside of this radius. We find that, on average, over half of all galaxies between R200 and 2R200 from their host at $z$ = 0 are backsplash galaxies, but that this fraction is dependent on the dynamical state of a cluster, as dynamically relaxed clusters have a greater backsplash fraction. We also find that this population is mostly developed at recent times ($z$ ≲ 0.4), and is dependent on the recent history of a cluster. Finally, we show that the dynamical state of a given cluster, and thus the fraction of backsplash galaxies in its outskirts, can be predicted based on observational properties of the cluster.
Publisher: Oxford University Press (OUP)
Date: 23-10-2018
Publisher: Oxford University Press (OUP)
Date: 29-07-2022
Abstract: Close pairs of galaxies have been broadly studied in the literature as a way to understand galaxy interactions and mergers. In observations, they are usually defined by setting a maximum separation in the sky and in velocity along the line of sight, and finding galaxies within these ranges. However, when observing the sky, projection effects can affect the results, by creating spurious pairs that are not close in physical distance. In this work, we mimic these observational techniques to find pairs in the three hundred simulations of clusters of galaxies. The galaxies’ 3D coordinates are projected into 2D, with Hubble flow included for their line-of-sight velocities. The pairs found are classified into ‘good’ or ‘bad’ depending on whether their 3D separations are within the 2D spatial limit or not. We find that the fraction of good pairs can be between 30 and 60 per cent depending on the thresholds used in observations. Studying the ratios of observable properties between the pair member galaxies, we find that the likelihood of a pair being ‘good’ can be increased by around 40, 20, and 30 per cent if the given pair has, respectively, a mass ratio below 0.2, metallicity ratio above 0.8, or colour ratio below 0.8. Moreover, shape and stellar-to-halo mass ratios, respectively, below 0.4 and 0.2 can increase the likelihood by 50 to 100 per cent. These results suggest that these properties can be used to increase the chance of finding good pairs in observations of galaxy clusters and their environment.
Publisher: Oxford University Press (OUP)
Date: 09-01-2023
Abstract: We study the nature of the low-redshift circumgalactic medium (CGM) in the Simba cosmological simulations as traced by ultraviolet absorption lines around galaxies in bins of stellar mass ($\\mbox{$M_\\star $}\\, & 10^{10}{\\rm M}_\\odot$) for star-forming, green valley and quenched galaxies at impact parameters r⊥ ≤ 1.25r200. We generate synthetic spectra for H i , Mg ii , C ii , Si iii , C iv , and O vi , fit Voigt profiles to obtain line properties, and estimate the density, temperature, and metallicity of the absorbing gas. We find that CGM absorbers are most abundant around star-forming galaxies with $\\mbox{$M_\\star $}\\, & 10^{11}\\,\\,{\\rm M}_{\\odot }$, while the abundance of green valley galaxies show similar behaviour to those of quenched galaxies, suggesting that the CGM ‘quenches’ before star formation ceases. H i absorbing gas exists across a broad range of cosmic phases [condensed gas, diffuse gas, hot halo gas, and Warm-Hot Intergalactic Medium (WHIM)], while essentially all low ionization metal absorption arises from condensed gas. O vi absorbers are split between hot halo gas and the WHIM. The fraction of collisionally ionized CGM absorbers is $\\sim 25{\\text{--}}55{{\\ \\rm per\\ cent}}$ for C iv and $\\sim 80{\\text{--}}95{{\\ \\rm per\\ cent}}$ for O vi , depending on stellar mass and impact parameter. In general, the highest column density absorption features for each ion arise from dense gas. Satellite gas, defined as that within 10r1/2,⋆, contributes $\\sim 3{{\\ \\rm per\\ cent}}$ of overall H i absorption but $\\sim 30{{\\ \\rm per\\ cent}}$ of Mg ii absorption, with the fraction from satellites decreasing with increasing ion excitation energy.
Publisher: Oxford University Press (OUP)
Date: 23-09-2021
Abstract: Gas infalling into the gravitational potential wells of massive galaxy clusters is expected to experience one or more shocks on its journey to becoming part of the intracluster medium (ICM). These shocks are important for setting the thermodynamic properties of the ICM and can therefore impact cluster observables such as X-ray emission and the Sunyaev–Zel’dovich (SZ) effect. We investigate the possibility of detecting signals from cluster shocks in the averaged thermal SZ profiles of galaxy clusters. Using zoom-in hydrodynamic simulations of massive clusters from the Three Hundred Project, we show that if cluster SZ profiles are stacked as a function of R/R200m, shock-induced features appear in the averaged SZ profile. These features are not accounted for in standard fitting formulae for the SZ profiles of galaxy clusters. We show that the shock features should be detectable with s les of clusters from ongoing and future SZ surveys. We also demonstrate that the location of these features is correlated with the cluster accretion rate, as well as the location of the cluster splashback radius. Analyses of ongoing and future surveys, such as SPT-3g, AdvACT, Simons Observatory, and CMB-S4, which include gas shocks will gain a new handle on the properties and dynamics of the outskirts of massive haloes, both in gas and in mass.
Publisher: Oxford University Press (OUP)
Date: 12-04-2023
Abstract: Using the data set of The Three Hundred project, i.e. 324 hydrodynamical resimulations of cluster-sized haloes and the regions of radius 15 ${{h^{-1}\\, {\\rm Mpc}}}$ around them, we study galaxy pairs in high-density environments. By projecting the galaxies’ 3D coordinates onto a 2D plane, we apply observational techniques to find galaxy pairs. Based on a previous theoretical study on galaxy groups in the same simulations, we are able to classify the observed pairs into ‘true’ or ‘false’, depending on whether they are gravitationally bound or not. We find that the fraction of true pairs (purity) crucially depends on the specific thresholds used to find the pairs, ranging from around 30 to more than 80 per cent in the most restrictive case. Nevertheless, in these very restrictive cases, we see that the completeness of the s le is low, failing to find a significant number of true pairs. Therefore, we train a machine learning algorithm to help us identify these true pairs based on the properties of the galaxies that constitute them. With the aid of the machine learning model trained with a set of properties of all the objects, we show that purity and completeness can be boosted significantly using the default observational thresholds. Furthermore, this machine learning model also reveals the properties that are most important when distinguishing true pairs, mainly the size and mass of the galaxies, their spin parameter, gas content, and shape of their stellar components.
Publisher: American Astronomical Society
Date: 25-05-2018
Publisher: Oxford University Press (OUP)
Date: 08-03-2022
Abstract: We perform a systematic study of the recently discovered Fundamental Plane of galaxy clusters (CFP) using ∼250 simulated clusters from The Three Hundred project, focusing on the stability of the plane against different temperature definitions and its dependence on the dynamical relaxation state of clusters. The CFP is characterized by $T\\propto M_\\mathrm{s}^\\alpha \\, r_\\mathrm{s}^\\beta$, defined with the gas temperature (T) and the characteristic halo scale radius and mass (rs and Ms) assuming a Navarro–Frenk–White halo description. We explore two definitions of weighted temperatures, namely mass-weighted and spectroscopic-like temperatures, in three radial ranges. The Three Hundred project clusters at z = 0 lie on a thin plane whose parameters (α, β) and dispersion (0.015–0.030 dex) depend on the gas temperature definition. The CFP for mass-weighted temperatures is closer to the virial equilibrium expectation (α = 1, β = −1) with a smaller dispersion. For gas temperatures measured within $500\\ h^{-1}$ kpc, the resulting CFP deviates the most from the virial expectation and shifts towards the similarity solution for a secondary infall model (α = 1.5, β = −2). Independently of the temperature definition, we find that clusters at z = 1 and relaxed clusters form a CFP similar to the virial expectation, unlike disturbed clusters exhibiting stronger evolution. Only systems formed over the last 4 Gyr present a CFP that is closer to the similarity solution. All these findings are compatible with the CFP obtained for a Cluster Lensing And Supernova survey with Hubble subs le excluding the hottest clusters with TX & 12 keV.
Publisher: Oxford University Press (OUP)
Date: 27-11-2021
Abstract: Galaxy clusters grow by accreting galaxies from the field and along filaments of the cosmic web. As galaxies are accreted they are affected by their local environment before they enter (pre-processing), and traverse the cluster potential. Observations that aim to constrain pre-processing are challenging to interpret because filaments comprise a heterogeneous range of environments including groups of galaxies embedded within them and backsplash galaxies that contain a record of their previous passage through the cluster. This motivates using modern cosmological simulations to dissect the population of galaxies found in filaments that are feeding clusters, to better understand their history, and aid the interpretation of observations. We use zoom-in simulations from The ThreeHundred project to track haloes through time and identify their environment. We establish a benchmark for galaxies in cluster infall regions that supports the reconstruction of the different modes of pre-processing. We find that up to 45 per cent of all galaxies fall into clusters via filaments (closer than 1 h−1Mpc from the filament spine). 12 per cent of these filament galaxies are long-established members of groups and between 30 and 60 per cent of filament galaxies at R200 are backsplash galaxies. This number depends on the cluster’s dynamical state and sharply drops with distance. Backsplash galaxies return to clusters after deflecting widely from their entry trajectory, especially in relaxed clusters. They do not have a preferential location with respect to filaments and cannot collapse to form filaments. The remaining pristine galaxies (∼30–60 per cent) are environmentally affected by cosmic filaments alone.
Publisher: American Physical Society (APS)
Date: 24-01-2013
Publisher: Oxford University Press (OUP)
Date: 08-08-2023
Abstract: We introduce a new chemical enrichment and stellar feedback model into GIZMO, using the SIMBA sub-grid models as a base. Based on the state-of-the-art chemical evolution model of Kobayashi et al., SIMBA-C tracks 34 elements from H→Ge and removes SIMBA’s instantaneous recycling approximation. Furthermore, we make some minor improvements to SIMBA’s base feedback models. SIMBA-C provides significant improvements on key diagnostics such as the knee of the z = 0 galaxy stellar mass function, the faint end of the main sequence, and the ability to track black holes in dwarf galaxies. SIMBA-C also matches better with recent observations of the mass–metallicity relation at z = 0, 2. By not assuming instantaneous recycling, SIMBA-C provides a much better match to galactic abundance ratio measures such as [O/Fe] and [N/O]. SIMBA-C thus opens up new avenues to constrain feedback models using detailed chemical abundance measures across cosmic time.
Publisher: Oxford University Press (OUP)
Date: 23-04-2020
Abstract: Upcoming wide-field surveys are well suited to studying the growth of galaxy clusters by tracing galaxy and gas accretion along cosmic filaments. We use hydrodynamic simulations of volumes surrounding 324 clusters from The ThreeHundred project to develop a framework for identifying and characterizing these filamentary structures and associating galaxies with them. We define three-dimensional reference filament networks reaching 5R200 based on the underlying gas distribution and quantify their recovery using mock galaxy s les mimicking observations such as those of the WEAVE Wide-Field Cluster Survey. Since massive galaxies trace filaments, they are best recovered by mass-weighting galaxies or imposing a bright limit (e.g. & L*) on their selection. We measure the transverse gas density profile of filaments, derive a characteristic filament radius of ≃ 0.7–1 h−1Mpc, and use this to assign galaxies to filaments. For different filament extraction methods, we find that at R & R200, ∼15–$20{{\\ \\rm per\\ cent}}$ of galaxies with M* & 3 × 109M⊙ are in filaments, increasing to $\\sim 60{{\\ \\rm per\\ cent}}$ for galaxies more massive than the Milky Way. The fraction of galaxies in filaments is independent of cluster mass and dynamical state and is a function of cluster-centric distance, increasing from ∼13 per cent at 5R200 to ∼21 per cent at 1.5R200. As a bridge to the design of observational studies, we measure the purity and completeness of different filament galaxy selection strategies. Encouragingly, the overall three-dimensional filament networks and ∼67 per cent of the galaxies associated with them are recovered from two-dimensional galaxy positions.
Publisher: Oxford University Press (OUP)
Date: 17-04-2021
Abstract: We study the connection between morphology and dynamical state of the simulated galaxy clusters in z ∈ [0, 1.031] from The Three Hundred project. We quantify cluster dynamical state using a combination of dynamical indicators from theoretical measures and compare this combined parameter, χ, with the results from morphological classifications. The dynamical state of the cluster s le shows a continuous distribution from dynamically relaxed, more abundant at lower redshift, to hybrid and disturbed. The dynamical state presents a clear dependence on the radius, with internal regions more relaxed than outskirts. The morphology from multiwavelength mock observation of clusters in X-ray, optical, and Sunyaev–Zel’dovich (SZ) effect images is quantified by M – a combination of six parameters for X-ray and SZ maps and the offsets between the optical position of the brightest cluster galaxy (BCG) and the X-ray/SZ centroids. All the morphological parameters are highly correlated with each other, while they show a moderately strong correlation with the dynamical χ parameter. The X-ray or SZ peaks are less affected by the dynamical state than centroids, which results in reliable tracers of the cluster density peak. The principal source of contamination in the relaxed cluster fraction, inferred from morphological parameters, is due to dynamically hybrid clusters. Compared to in idual parameters, which consider only one aspect of cluster property (e.g. only clumping or asymmetry), the combined morphological and dynamical parameters (M and χ) collect more information and provide a single and more accurate estimation of the cluster dynamical state.
Publisher: Oxford University Press (OUP)
Date: 21-10-2023
Publisher: Oxford University Press (OUP)
Date: 17-06-2021
Abstract: Concentration is one of the key dark matter halo properties that could drive the scatter in the stellar-to-halo mass relation of massive clusters. We derive robust photometric stellar masses for a s le of brightest central galaxies (BCGs) in SDSS redmapper clusters at 0.17 & z & 0.3, and split the clusters into two equal-halo mass subs les by their BCG stellar mass $M_*^{\\mathrm{BCG}}$. The weak lensing profiles ΔΣ of the two cluster subs les exhibit different slopes on scales below $1\\, h^{-1}\\, {\\mathrm{Mpc}}$. To interpret such discrepancy, we perform a comprehensive Bayesian modelling of the two ΔΣ profiles by including different levels of miscentring effects between the two subs les as informed by X-ray observations. We find that the two subs les have the same average halo mass of $1.74\\times 10^{14}\\, h^{-1}\\, \\mathrm{M}_{\\odot }$, but the concentration of the low-$M_*^{\\mathrm{BCG}}$ clusters is $5.87_{-0.60}^{+0.77}$, ∼1.5σ smaller than that of their high-$M_*^{\\mathrm{BCG}}$ counterparts ($6.95_{-0.66}^{+0.78}$). Furthermore, both cluster weak lensing and cluster-galaxy cross-correlations indicate that the large-scale bias of the low-$M_*^{\\mathrm{BCG}}$, low-concentration clusters are ${\\sim}10{{\\ \\rm per\\ cent}}$ higher than that of the high-$M_*^{\\mathrm{BCG}}$, high-concentration systems, hence possible evidence of the cluster assembly bias effect. Our results reveal a remarkable physical connection between the stellar mass within $20{-}30\\, h^{-1}\\, {\\mathrm{kpc}}$, the dark matter mass within ${\\sim}200\\, h^{-1}\\, {\\mathrm{kpc}}$, and the cosmic overdensity on scales above $10\\, h^{-1}\\, {\\mathrm{Mpc}}$, enabling a key observational test of theories of co-evolution between massive clusters and their central galaxies.
Publisher: IOP Publishing
Date: 04-2022
DOI: 10.1088/1475-7516/2022/04/047
Abstract: Chameleon gravity is an ex le of a model that gives rise to interesting phenomenology on cosmological scales while simultaneously possessing a screening mechanism, allowing it to avoid solar system constraints. Such models result in non-linear field equations, which can be solved analytically only in simple highly symmetric systems. In this work we study the equation of motion of a scalar-tensor theory with chameleon screening using the finite element method. More specifically, we solve the field equation for spherical and triaxial NFW cluster-sized halos. This allows a detailed investigation of the relationship between the NFW concentration and the virial mass parameters and the magnitude of the chameleon acceleration, as measured at the virial radius. In addition, we investigate the effects on the chameleon acceleration due to halo triaxiality. We focus on the parameter space regions that are still allowed by the observational constraints. We find that given our dataset, the largest allowed value for the chameleon-to-NFW acceleration ratio at the virial radius is ∼ 10 -7 . This result strongly indicates that the chameleon models that are still allowed by the observational constraints would not lead to any measurable effects on galaxy cluster scales. Nonetheless, we also find that there is a direct relationship between the NFW potential and the chameleon-to-NFW acceleration ratio at the virial radius. Similarly, there is a direct (yet a much more complicated) relationship between the NFW concentration, the virial mass and the acceleration ratios at the virial radius. Finally, we find that triaxiality introduces extra directional effects on the acceleration measurements. These effects in combination could potentially be used in future observational searches for fifth forces.
Publisher: Oxford University Press (OUP)
Date: 09-06-2021
Abstract: Using hydrodynamical simulations, we study how well the underlying gravitational potential of a galaxy cluster can be modelled dynamically with different types of tracers. In order to segregate different systematics and the effects of varying estimator performances, we first focus on applying a generic minimal assumption method (oPDF) to model the simulated haloes using the full 6D phase-space information. We show that the halo mass and concentration can be recovered in an ensemble unbiased way, with a stochastic bias that varies from halo to halo, mostly reflecting deviations from steady state in the tracer distribution. The typical systematic uncertainty is ∼0.17 dex in the virial mass and ∼0.17 dex in the concentration as well when dark matter (DM) particles are used as tracers. The dynamical state of satellite galaxies are close to that of DM particles, while intracluster stars are less in a steady state, resulting in an ∼0.26-dex systematic uncertainty in mass. Compared with galactic haloes hosting Milky-Way-like galaxies, cluster haloes show a larger stochastic bias in the recovered mass profiles. We also test the accuracy of using intracluster gas as a dynamical tracer modelled through a generalized hydrostatic equilibrium equation, and find a comparable systematic uncertainty in the estimated mass to that using DM. Lastly, we demonstrate that our conclusions are largely applicable to other steady-state dynamical models including the spherical Jeans equation, by quantitatively segregating their statistical efficiencies and robustness to systematics. We also estimate the limiting number of tracers that leads to the systematics-dominated regime in each case.
Publisher: Oxford University Press (OUP)
Date: 21-10-2023
Location: United Kingdom of Great Britain and Northern Ireland
Location: China
Start Date: 2018
End Date: 2021
Funder: University of Queensland
View Funded ActivityStart Date: 2015
End Date: 2015
Funder: University of Western Australia
View Funded ActivityStart Date: 2014
End Date: 2014
Funder: University of Western Australia
View Funded ActivityStart Date: 2021
End Date: 2024
Funder: Science and Technology Facilities Council
View Funded Activity