On the Separation between the Brightest Cluster Galaxy and the Intracluster Light
- 1Yonsei University
Abstract
We present a model-based framework to define an aperture separation between the brightest cluster galaxy (BCG) and the intracluster light (ICL). Using the intrinsic BCG and ICL components predicted by the semianalytic model FEGA25 , we determine, for each halo, the aperture radius that minimizes the bias in the recovered ICL mass. The optimal radius is obtained by balancing the BCG stellar mass lying outside the aperture with the ICL mass enclosed within it. At z = 0, the optimal aperture in physical units increases with halo mass approximately as r cut ∝ M halo 0.28 , close to the expected virial scaling. When expressed in units of the virial radius, the aperture becomes nearly independent of halo mass, with r cut / R vir ≃ 0.045 at 10 ¹⁴ M ⊙ . Applying the resulting aperture prescriptions, we recover the intrinsic BCG mass to better than 8% (lowest percentile), while the ICL mass is recovered with median values very close to unity and an average scatter of ±3%. Extending the analysis to z = 1 and 2, we find that the mass trends remain similar, with both the slope and intercept of the r cut / R vir relation remaining stable. Robustness tests show that the inferred aperture is most sensitive to the ICL concentration and BCG size, but the main trends are preserved. Our results provide a physically motivated aperture definition for connecting observational BCG–ICL measurements to intrinsic model components.
Related
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BibTeX
@article{contini2026separation,
title = {{On the Separation between the Brightest Cluster Galaxy and the Intracluster Light}},
author = {Emanuele Contini and Sukyoung K. Yi},
journal = {The Astrophysical Journal Supplement Series},
year = {2026},
month = nov,
doi = {10.3847/1538-4365/aeb2e4},
url = {https://iopscience.iop.org/article/10.3847/1538-4365/aeb2e4},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - On the Separation between the Brightest Cluster Galaxy and the Intracluster Light
AU - Emanuele Contini
AU - Sukyoung K. Yi
PY - 2026
DA - 2026/11/05
JO - The Astrophysical Journal Supplement Series
DO - 10.3847/1538-4365/aeb2e4
UR - https://iopscience.iop.org/article/10.3847/1538-4365/aeb2e4
AB - We present a model-based framework to define an aperture separation between the brightest cluster galaxy (BCG) and the intracluster light (ICL). Using the intrinsic BCG and ICL components predicted by the semianalytic model FEGA25 , we determine, for each halo, the aperture radius that minimizes the bias in the recovered ICL mass. The optimal radius is obtained by balancing the BCG stellar mass lying outside the aperture with the ICL mass enclosed within it. At z = 0, the optimal aperture in physical units increases with halo mass approximately as r cut ∝ M halo 0.28 , close to the expected virial scaling. When expressed in units of the virial radius, the aperture becomes nearly independent of halo mass, with r cut / R vir ≃ 0.045 at 10 ¹⁴ M ⊙ . Applying the resulting aperture prescriptions, we recover the intrinsic BCG mass to better than 8% (lowest percentile), while the ICL mass is recovered with median values very close to unity and an average scatter of ±3%. Extending the analysis to z = 1 and 2, we find that the mass trends remain similar, with both the slope and intercept of the r cut / R vir relation remaining stable. Robustness tests show that the inferred aperture is most sensitive to the ICL concentration and BCG size, but the main trends are preserved. Our results provide a physically motivated aperture definition for connecting observational BCG–ICL measurements to intrinsic model components.
SN - 0067-0049
SN - 1538-4365
ER -