A study tests four pressure profile models in galaxy clusters
A recent analysis tests the universal validity of four distinct functional forms for describing how gas pressure behaves in galaxy clusters. The research relies on data from the Sunyaev-Zel'dovich (SZ) effect and seeks to determine if any model stands out in reproducing real observations. 🔭
Methodology and models under scrutiny
The work examines the gNFW (generalized Navarro-Frenk-White), beta, polytropic, and exponential models. To do so, it processes data from 3496 clusters from the ACT-DR4 catalog, stacking them over Compton parameter maps from ACT-DR6. This process generates an average angular profile that is then compared with the predictions of each theory.
Statistical analysis approach:- Uses Markov Chain Monte Carlo (MCMC) chains in multiple stages to fit the models to the data.
- Repeats the process on cluster subsamples, grouped by mass and redshift.
- Evaluates the ability of each functional form to reproduce the measured profiles within their error margins.
Searching for a universal pressure model is like looking for a pair of pants that fits the whole neighborhood: it might work in broad strokes, but for a tailored suit, it's better to look at each case individually.
Results and detected trends
The findings indicate that no model clearly stands out over the others at the full population level. All succeed in reproducing the profiles within the error bars. However, when analyzing subsamples, subtle dependencies emerge.
Key observations in subsamples:- The most massive clusters show broader and more pronounced pressure profiles.
- Clusters with low redshift also exhibit these characteristics.
- The dispersion between individual clusters is significant.
Implications for observational cosmology
The main conclusion points out that studies using only SZ data on large scales probably cannot precisely constrain distinct profile models. The existence of residual trends and dispersion questions the idea of a single universal model when high precision is needed. The