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R. M. Batalha

Publications and source records attributed to R. M. Batalha.

2 recordsLinked to original sources

CHEX-MATE: Density profile reconstruction in galaxy clusters

We investigated the reconstruction of the intra-cluster medium radial density profiles in galaxy clusters, focusing on the impact of cluster morphology, dynamical state, and methodological choices, within the framework of the CHEX-MATE project. Using a sample of 109 simulated galaxy clusters analysed along 40 independent lines of sight, we compared azimuthal mean and median techniques for deprojection. We find that azimuthal median-based density profiles recover the true gas density with negligible bias over the radial range $[0.15-1.3] R_{500}$. Mean based profiles are affected by the presence of substructures. While an accurate masking of clumps or substructures can reduce the bias to $< 5\%$, the discrepancy increases substantially in disturbed systems or when substructures remain unresolved. The mean-to-median density ratio statistically traces projected gas inhomogeneities, although intrinsic scatter and projection effects limit its use for individual clusters. The complementary use of mean and median profiles therefore provides the most complete approach for large X-ray cluster samples.

astro-ph.CO↗

CHEX-MATE: Robust reconstruction of temperature profiles in galaxy clusters with XMM-Newton

The "Cluster HEritage project with \xmm: Mass Assembly and Thermodynamics at the Endpoint of structure formation" (CHEX-MATE) is a multi-year Heritage program, to obtain homogeneous XMM-Newton observations of a representative sample of 118 galaxy clusters. The observations are tuned to reconstruct the distribution of the main thermodynamic quantities of the ICM up to $R_{500}$ and to obtain individual mass measurements, via the hydrostatic-equilibrium equation, with a precision of 15-20%. Temperature profiles are a necessary ingredient for the scientific goals of the project and it is thus crucial to derive the best possible temperature measurements from our data. This is why we have built a new pipeline for spectral extraction and analysis of XMM-Newton data, based on a new physically motivated background model and on a Bayesian approach with Markov Chain Monte Carlo (MCMC) methods, that we present in this paper for the first time. We applied this new method to a subset of 30 galaxy clusters representative of the CHEX-MATE sample and show that we can obtain reliable temperature measurements up to regions where the source intensity is as low as 20% of the background, keeping systematic errors below 10%. We compare the median profile of our sample and the best fit slope at large radii with literature results and we find a good agreement with other measurements based on XMM-Newton data. Conversely, when we exclude from our analysis the most contaminated regions, where the source intensity is below 20 of the background, we find significantly flatter profiles, in agreement with predictions from numerical simulations and independent measurements with a combination of Sunyaev-Zeldovich and X-ray imaging data.

astro-ph.CO↗