Abstract
ABSTRACT We explore the relation between diffuse intracluster light (central galaxy included) and the galaxy cluster (baryonic and dark) matter distribution using a sample of 528 clusters at 0.2 ≤ z ≤ 0.35 found in the Dark Energy Survey (DES) Year 1 data. The surface brightness of the diffuse light shows an increasing dependence on cluster total mass at larger radius, and appears to be self-similar with a universal radial dependence after scaling by cluster radius. We also compare the diffuse light radial profiles to the cluster (baryonic and dark) matter distribution measured through weak lensing and find them to be comparable. The IllustrisTNG galaxy formation simulation, TNG300, offers further insight into the connection between diffuse stellar mass and cluster matter distributions – the simulation radial profile of the diffuse stellar component does not have a similar slope with the total cluster matter content, although that of the cluster satellite galaxies does. Regardless of the radial trends, the amount of diffuse stellar mass has a low-scatter scaling relation with cluster’s total mass in the simulation, out-performing the total stellar mass of cluster satellite galaxies. We conclude that there is no consistent evidence yet on whether or not diffuse light is a faithful radial tracer of the cluster matter distribution. Nevertheless, both observational and simulation results reveal that diffuse light is an excellent indicator of the cluster’s total mass.
Highlights
Galaxy clusters are permeated by a diffuse component known as the intracluster light (ICL), composed of stars that do not appear to be bound to any of the galaxies in a cluster
We present for the first time a direct comparison of the radial dependence of the diffuse light surface brightness and the weak-lensing measured cluster matter distribution, for a statistically large cluster sample with high S/N diffuse light measurements to a cluster radial range of 1 Mpc
(i) Strong correlation between diffuse light brightness and cluster mass at large radius: We observe that more massive clusters have more diffuse light in the regions outside 20 kpc of the cluster centre, and the mass dependence becomes steeper with increasing cluster radius
Summary
Galaxy clusters are permeated by a diffuse component known as the intracluster light (ICL), composed of stars that do not appear to be bound to any of the galaxies in a cluster. Given its low surface brightness level, diffuse ICL is difficult to observe, it is an important component of galaxy clusters. Another evidence of the connection between dark matter and ICL was shown by Montes & Trujillo (2018), there, the 3D slope of diffuse light measured in six clusters in the Hubble Frontier Fields. Zhang et al (2019b, hereafter Z19) discovered that the ratio between diffuse light surface brightness and a weak-lensing measurement-based cluster mass–density model appears to be flat at cluster radius greater than 100 kpc, and that diffuse ICL radial profiles are self-similar. This paper is organized as follows: in Section 2 we describe the DES data (e.g. images, source catalogues, and galaxy cluster catalogues) and our analysis methods.
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