An Investigation of intra-cluster light evolution using cosmological hydro-dynamical simulations

TL;DR

This study uses cosmological hydro-dynamical simulations to produce mock images of galaxy clusters, analyzing how observational parameters affect measurements of intra-cluster light (ICL) and highlighting the importance of consistent definitions.

Contribution

First simulation-based investigation into how observational factors influence ICL measurements, providing insights for better comparison between observations and theory.

Findings

Point spread function width significantly affects ICL fraction measurement.

ICL fraction depends strongly on surface brightness limit (SBL).

Measured ICL fraction decreases with halo mass at fixed SBL and redshift.

Abstract

The intra-cluster light (ICL) in observations is usually identified through the surface brightness limit method. In this paper, for the first time we produce the mock images of galaxy groups and clusters using a cosmological hydro- dynamical simulation, to investigate the ICL fraction and focus on its dependence on observational parameters, e.g., the surface brightness limit (SBL), the effects of cosmological redshift dimming, point spread function and CCD pixel size. Detailed analyses suggest that the width of point spread function has a significant effect on the measured ICL fraction, while the relatively small pixel size shows almost no influence. It is found that the measured ICL fraction depends strongly on the SBL. At a fixed SBL and redshift, the measured ICL fraction decreases with increasing halo mass, while with a much faint SBL, it does not depend on halo mass at low redshifts. In our work, the measured ICL fraction shows clear dependence on the cosmological redshift dimming effect. It is found that there are more mass locked in ICL component than light, suggesting that the use of a constant mass-to-light ratio at high surface brightness levels will lead to an underestimate of ICL mass. Furthermore, it is found that the radial profile of ICL shows a characteristic radius which is almost independent of halo mass. The current measurement of ICL from observations has a large dispersion due to different methods, and we emphasize the importance of using the same definition when observational results are compared with the theoretical predictions.