New observational recipes for measuring dynamical state of galaxy clusters

Abstract

During cluster assembly, a cluster's virialization process leaves behind signatures that can provide information on its dynamical state. However, no clear consensus yet exists on the best way to achieve this. Therefore, we attempt to derive improved recipes for classifying the dynamical state of clusters in observations using cosmological simulations. Cluster halo mass and their subhalos' mass are used to $10^{14}{M}_{\odot }{h}^{-1}$ and $10^{10}{M}_{\odot }{h}^{-1}$ to calculate five independent dynamical state indicators. We experiment with recipes by combining two to four indicators for detecting specific merger stages like recent and ancient mergers. These recipes are made by plotting merging clusters and a control sample of relaxed clusters in multiple indicators parameter space, and then applying a rotation matrix method to derive the best way to separate mergers from the control sample. The success of the recipe is quantified using the success rate and the overlap percentage of the merger and control histograms along the newly rotated $x$-axis. This provides us with recipes using different numbers of combined indicators and for different merger stage. Among the recipes, the stellar mass gap and center offset are the first and second most dominant of the indicators, and using more indicators improves the effectiveness of the recipe. When applied to observations, our results show good agreement with literature values of cluster dynamical state.

17pages, 9 figures, 3 tables, ApJ Accepted

References in corpus (18)

• Images, structural properties and metal abundances of galaxy clusters observed with Chandra ACIS-I at 0.1<z<1.3
• On the efficiency and reliability of cluster mass estimates based on member galaxies
• The Preferential Tidal Stripping of Dark Matter versus Stars in Galaxies
• The Three Hundred Project: Backsplash galaxies in simulations of clusters
• A New Method to Constrain the Appearance and Disappearance of Observed Jellyfish Galaxy Tails
• What to expect from dynamical modelling of cluster haloes II. Investigating dynamical state indicators with Random Forest
• The Three Hundred: Cluster Dynamical States and Relaxation Time Scale
• The formation of the brightest cluster galaxy and intracluster light in cosmological N-body simulations with the Galaxy Replacement Technique
• Investigating the Projected Phase Space of Gaussian and Non-Gaussian Clusters
• The impact of the dynamical state of galaxy groups on the stellar populations of central galaxies
• The First Fall is the Hardest: The Importance of Peculiar Galaxy Dynamics at Infall Time for Tidal Stripping Acting at the Centers of Groups and Clusters
• DS+: a method for the identification of cluster substructures
• Tracking Halo Orbits and Their Mass Evolution around Large-scale Filaments
• On the choice of the most suitable indicator for the assembly state of dark matter haloes through cosmic time
• Unexpected dancing partners: Tracing the coherence between the spin and motion of dark matter halos
• The dependence of cluster galaxy properties on the central entropy of their host cluster
• Two merging galaxy clusters with very hot shock fronts observed shortly before pericentric passage
• Is Abell 2261 a fossil galaxy cluster in a transitional dynamical state?