Characterizing galaxy clusters by their gravitational potential: systematics of cluster potential reconstruction

TL;DR

This study demonstrates that gravitational potential measurements of galaxy clusters have smaller biases and scatter compared to hydrostatic mass estimates, making them a promising alternative for cosmological research.

Contribution

The paper shows that cluster gravitational potentials can be reconstructed with less bias and scatter than hydrostatic mass estimates, offering a new approach for cosmological studies.

Findings

Bias in reconstructed potential is 6%, less than 13% for hydrostatic mass.

Scatter in potential reconstruction decreases by about 35%.

Potential characterization is a promising alternative to mass in cluster cosmology.

Abstract

Context. Biases in mass measurements of galaxy clusters are one of the major limiting systematics in constraining cosmology with clusters. Aims. We aim to demonstrate that the systematics associated with cluster gravitational potentials are smaller than the hydrostatic mass bias and that cluster potentials could therefore be a good alternative to cluster masses in cosmological studies. Methods. Using cosmological simulations of galaxy clusters, we compute the biases in the hydrostatic mass (HE mass) and those in the gravitational potential, reconstructed from measurements at X-ray and millimeter wavelengths. In particular, we investigate the effects of the presence of substructures and of non-thermal pressure support on both the HE mass and the reconstructed potential. Results. We find that the bias in the reconstructed potential (6%) is less than that of the HE mass (13%), and that the scatter in the reconstructed potential decreases by about 35% with respect to that in the HE mass. Conclusions. This study shows that characterizing galaxy clusters by their gravitational potential is a promising alternative to using cluster masses in cluster cosmology.