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Mature but Still Growing: JWST Detection of the Earliest Intracluster Light at z ∼ 2

delete2026-05-01
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PRE
AI
H
Hyungjin Joo
M
M. James Jee *
K
Kyle Finner
Z
Zachary P. Scofield
S
Sangjun Cha
J
Jinhyub Kim
R
Ranga‐Ram Chary
F
Faisst, Andreas
B
Bomee Lee
DOI:10.3847/2041-8213/ae5c9fdelete
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Abstract

Abstract

En 中文
We present a JWST analysis of intracluster light (ICL) in XLSSC 122 at z = 1.98, currently the most distant known strong-lensing galaxy cluster with an evolved member population. Using deep JWST imaging complemented by Hubble Space Telescope data and careful control of systematics, we robustly detect diffuse emission extending to several hundred kiloparsecs from the brightest cluster galaxy (BCG) down to similar to 29magarcsec(-2). Multicomponent point-spread-function-convolved S & eacute;rsic modeling separates the surface brightness profiles into three components: a BCG core, a BCG envelope, and an ICL component, with stable S & eacute;rsic indices across wavelengths. Nearly flat color profiles indicate minimal radial variation in the stellar populations of the BCG envelope and the ICL. The median ICL fraction measured across seven bands is similar to 17%, demonstrating that the buildup of intracluster stars in massive halos was already well underway by z similar to 2. The ICL fraction peaks near 5000 & Aring; in the rest frame, which provides the first confirmation at z > 1 that this characteristic rise is a feature of dynamically active clusters. We also detect a southern excess of ICL relative to the best-fit S & eacute;rsic model and quantify it using wavelet-based modeling, providing additional support that this system is dynamically active. The BCG + ICL light distribution and strong-lensing mass map show strong morphological agreement within similar to 100 kpc. These findings establish the ICL as an early forming and dynamically informative component of massive halos.
Keywords:
GALAXY CLUSTER
DARK-MATTER
REDSHIFT
ICL
I.
SPLASHBACK
ABUNDANT
TRACER
REGION
MASSES

Journal

Astrophysical Journal Letters cover
Astrophysical Journal Letters
IF:
11.7
Papers:
1.2W
Citations:
5.9W

Organization

U
university of california davis
Scholars:
3.3W
Papers: 2.6W
Citations: 45
University of California System cover
University of California System
Scholars:
37.2W
Papers: 33.6W
Citations: 6.6K
U
university of oxford
Scholars:
9.6W
Papers: 8.5W
Citations: 137
C
california institute of technology
Scholars:
2.4K
Papers: 1.0K
Citations: 0
Y
Yonsei University
Scholars:
4.7W
Papers: 4.5W
Citations: 5.2W
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