Galaxy clusters in simulations of the local Universe: a matter of constraints

Sorce, Jenny G.; Tempel, Elmo

doi:10.1093/mnras/sty505

Cited by 22 publications

(16 citation statements)

References 68 publications

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“…Although the differences in mean density and velocity fields are small, they change the mass of the large clusters by about at least 5 percent on average. When analyzing the specific clusters in the local Universe, Sorce & Tempel (2018) conclude that the grouping scheme used to remove non-linear motions in the catalogues that constrain the simulations affect the quality of the numerical clusters. These comparisons emphasise that the choice of grouping method is important in order to suppress the non-linear motions.…”

Section: Application Of Bayesian Groups For Constrained Simulationsmentioning

confidence: 99%

Bayesian group finder based on marked point processes

Tempel

Kruuse

Kipper

et al. 2018

A&A

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Context. Galaxy groups and clusters are formidable cosmological probes. They permit the studying of the environmental effects on galaxy formation. A reliable detection of galaxy groups is an open problem and is important for ongoing and future cosmological surveys. Aims. We propose a probabilistic galaxy group detection algorithm based on marked point processes with interactions. Methods. The pattern of galaxy groups in a catalogue is seen as a random set of interacting objects. The positions and the interactions of these objects are governed by a probability density. The parameters of the probability density were chosen using a priori knowledge. The estimator of the unknown cluster pattern is given by the configuration of objects maximising the proposed probability density. Adopting the Bayesian framework, the proposed probability density is maximised using a simulated annealing (SA) algorithm. At fixed temperature, the SA algorithm is a Monte Carlo sampler of the probability density. Hence, the method provides “for free” additional information such as the probabilities that a point or two points in the observation domain belong to the cluster pattern, respectively. These supplementary tools allow the construction of tests and techniques to validate and to refine the detection result. Results. To test the feasibility of the proposed methodology, we applied it to the well-studied 2MRS data set. Compared to previously published Friends-of-Friends (FoF) group finders, the proposed Bayesian group finder gives overall similar results. However for specific applications, like the reconstruction of the local Universe, the details of the grouping algorithms are important. Conclusions. The proposed Bayesian group finder is tested on a galaxy redshift survey, but more detailed analyses are needed to understand the actual capabilities of the algorithm regarding upcoming cosmological surveys. The presented mathematical framework permits adapting it easily for other data sets (in astronomy and in other fields of sciences). In cosmology, one promising application is the detection of galaxy groups in photometric galaxy redshift surveys, while taking into account the full photometric redshift posteriors.

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Section: Application Of Bayesian Groups For Constrained Simulationsmentioning

confidence: 99%

Bayesian group finder based on marked point processes

Tempel

Kruuse

Kipper

et al. 2018

A&A

Self Cite

View full text Add to dashboard Cite

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“…As in previous CoDa simulations, CoDa III 's initial conditions were constrained so as to produce facsimiles of the progenitors of the Local Group (See Sorce et al 2016;Sorce & Tempel 2018) within the Constrained Local Universe Simulations project (CLUES 3 ). We will use this unique opportunity to investigate the reionization of the Local Group in a forthcoming paper.…”

Section: Initial Conditions and Cosmologymentioning

confidence: 99%

The short ionizing photon mean free path at z=6 in Cosmic Dawn III, a new fully-coupled radiation-hydrodynamical simulation of the Epoch of Reionization

Lewis¹,

Ocvirk²,

Sorce³

et al. 2022

Preprint

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Recent determinations of the mean free path of ionising photons (mfp) in the intergalactic medium (IGM) at z = 6 are lower than many theoretical predictions. In order to gain insight into this issue, we investigate the evolution of the mfp in our new massive fully coupled radiation hydrodynamics cosmological simulation of reionization: Cosmic Dawn III (CoDa III). CoDa III's scale (94 3 cMpc 3 ) and resolution (8192 3 grid) make it particularly suitable to study the evolution of the IGM during the Epoch of Reionization (EoR). The simulation was performed with RAMSES-CUDATON on Summit, and used 131072 processors coupled to 24576 GPUs, making it the largest EoR simulation, and largest RAMSES simulation ever performed. A superior agreement with global constraints on reionization is obtained in CoDa III over CoDa II, especially for the evolution of the neutral hydrogen fraction and the cosmic photo-ionization rate, thanks to an improved calibration, later end of reionization (z = 5.6), and higher spatial resolution. Analyzing the mfp, we find that CoDa III reproduces the most recent observations very well, from z = 6 to z = 4.6. We show that the distribution of the mfp in CoDa III is bimodal, with short (neutral) and long (ionized) mfp modes, respectively, due to the patchiness of reionization and the co-existence of neutral versus ionized regions during the EoR. The neutral mode peaks at sub-kpc to kpc scales of mfp, while the ionized mode peak evolves from 0.1Mpc/h at z = 7 to ∼ 10 Mpc/h at z = 5.2. Computing the mfp as the average of the ionized mode provides the best match to the recent observational determinations. The distribution reduces to a single neutral (ionized) mode at z > 13 (z < 5).

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“…We use 200 constrained simulations designed to match the large scale structure around the Local Group within a ∼ 150 h −1 Mpc sphere radius. Local observational data used to constrain the initial conditions of the simulations are distances of galaxies and groups converted into peculiar velocities (Sorce & Tempel 2018;Sorce et al 2016b) that are bias minimized (Sorce 2015). The details of the algorithms and steps to get the simulations are given in Sorce et al (2019).…”

Section: Constrained Simulations and Virgo-like Halosmentioning

confidence: 99%

The Past History of Galaxy Clusters told by their present neighbors

Sorce,

Gottlöber,

Yepes

2020

Preprint

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Galaxy clusters can play a key role in modern cosmology provided their evolution is properly understood. However, observed clusters give us only a single timeframe of their dynamical state. Therefore, finding present observable data of clusters that are well correlated to their assembly history constitutes an inestimable tool for cosmology. Former studies correlating environmental descriptors of clusters to their formation history are dominated by halo mass -environment relations. This paper presents a mass-free correlation between the present neighbor distribution of cluster-size halos and the latter mass assembly history. From the Big Multidark simulation, we extract two large samples of random halos with masses ranging from Virgo to Coma cluster sizes. Additionally, to find the main environmental culprit for the formation history of the Virgo cluster, we compare the Virgosize halos to 200 Virgo-like halos extracted from simulations that resemble the local Universe. The number of neighbors at different cluster-centric distances permits discriminating between clusters with different mass accretion histories. Similarly to Virgo-like halos, clusters with numerous neighbors within a distance of about 2 times their virial radius experience a transition at z ≈ 1 between an active period of mass accretion, relative to the mean, and a quiet history. On the contrary, clusters with few neighbors share an opposite trend: from passive to active assembly histories. Additionally, clusters with massive companions within about 4 times their virial radius tend to have recent active merging histories. Therefore, the radial distribution of cluster neighbors provides invaluable insights into the past history of these objects.

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Galaxy clusters in simulations of the local Universe: a matter of constraints

Cited by 22 publications

References 68 publications

Bayesian group finder based on marked point processes

Bayesian group finder based on marked point processes

The short ionizing photon mean free path at z=6 in Cosmic Dawn III, a new fully-coupled radiation-hydrodynamical simulation of the Epoch of Reionization

The Past History of Galaxy Clusters told by their present neighbors

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