The Growth of Intracluster Light in XCS-HSC Galaxy Clusters from $0.1 < z < 0.5$

Furnell, Kate E. and Collins, Chris A. and Kelvin, Lee S. and Baldry, Ivan K. and James, Phil A. and Manolopoulou, Maria and Mann, Robert G. and Giles, Paul A. and Bermeo, Alberto and Hilton, Matthew and Wilkinson, Reese and Romer, A. Kathy and Vergara, Carlos and Bhargava, Sunayana and Stott, John P. and Mayers, Julian and Viana, Pedro (2021) The Growth of Intracluster Light in XCS-HSC Galaxy Clusters from $0.1 < z < 0.5$. Monthly Notices of the Royal Astronomical Society, 502 (2). pp. 2419-2437. ISSN 0035-8711

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Abstract

We estimate the Intracluster Light (ICL) component within a sample of 18clusters detected in XMM Cluster Survey (XCS) data using deep ($\sim$26.8 mag) Hyper Suprime Cam Subaru Strategic Program DR1 (HSC-SSP DR1)$i$-band data. We apply a rest-frame ${\mu}_{B} = 25 \\mathrm{mag/arcsec^{2}}$ isophotal threshold to our clusters, belowwhich we define light as the ICL within an aperture of $R_{X,500}$(X-ray estimate of $R_{500}$) centered on the Brightest Cluster Galaxy(BCG). After applying careful masking and corrections for flux lossesfrom background subtraction, we recover $\sim$20% of the ICL flux,approximately four times our estimate of the typical background at thesame isophotal level ($\sim$ 5%). We find that the ICL makes up about$\sim$ 24% of the total cluster stellar mass on average ($\sim$ 41%including the flux contained in the BCG within 50 kpc); this value iswell-matched with other observational studies andsemi-analytic/numerical simulations, but is significantly smaller thanresults from recent hydrodynamical simulations (even when measured in anobservationally consistent way). We find no evidence for any linksbetween the amount of ICL flux with cluster mass, but find a growth rateof $2-4$ for the ICL between $0.1 <z <0.5$. We conclude that theICL is the dominant evolutionary component of stellar mass in clustersfrom $z \sim 1$. Our work highlights the need for a consistent approachwhen measuring ICL alongside the need for deeper imaging, in order tounambiguously measure the ICL across as broad a redshift range aspossible (e.g. 10-year stacked imaging from the Vera C. RubinObservatory).