DISENTANGLING THE ICL WITH THE CHEFs: ABELL 2744 AS A CASE STUDY

Abstract

Measurements of the intracluster light (ICL) are still prone to methodological ambiguities and there are multiple techniques in the literature for that purpose, mostly based on the binding energy, the local density distribution, or the surface brightness. A common issue with these methods is the a priori assumption of a number of hypotheses on either the ICL morphology, its surface brightness level or some properties of the brightest cluster galaxy (BCG). The discrepancy on the results is high, and numerical simulations just bound the ICL fraction in present-day galaxy clusters to the range 10-50%. We developed a new algorithm based on the Chebyshev-Fourier functions (CHEFs) to estimate the ICL fraction without relying on any a priori assumption on the physical or geometrical characteristics of the ICL. We are able to not only disentangle the ICL from the galatic luminosity but mark out the limits of the BCG from the ICL in a natural way. We test our tecnique with the recently released data of the cluster Abell 2744, observed by the Frontier Fields program. The complexity of this multiple merging cluster system and the formidable depth of these images make it a challenging test case to prove the efficiency of our algorithm. We found a final ICL fraction of 19.17±2.87%, which is very consistent with numerical simulations.

MUSE spectroscopy and deep observations of a unique compact JWST target, lensing cluster CLIO

“…where σ is the standard deviation of the flux. In Figure 11, we compare the ICL fraction of CLIO with the cluster ICL studies of Krick et al (2006), Presotto et al (2014), Burke et al (2015), Morishita et al (2016) and Jiménez-Teja & Dupke (2016). It should be noted that there is currently no standard method for the determination of ICL fractions, as such each study mentioned here employs various limiting radii and masking processes.…”

On the Origin and Evolution of the Intra-Cluster Light: A Brief Review of the Most Recent Developments

“…The definition of the ICL is probably the most serious issue for observational studies ( [10,[13][14][15][16][17]), while it is much less complex in theoretical ones. A non-unique definition of the ICL makes comparisons among studies very complicated, and this applies not only between theoretical and observational works but also between the same "class".…”

Unveiling the Dynamical State of Massive Clusters through the ICL Fraction

“…Notice that this is a minimum condition, since if it is violated no method would be able to disentangle the two light distributions. CICLE has been successfully tested with mock data and applied to real data from cluster Abell 2744 (Jiménez-Teja & Dupke 2016).…”