Publications (20)
MrMARTIAN: A Multi-resolution Mass Reconstruction Algorithm Combining Free-form and Analytic Components
Sangjun Cha, M. James Jee
We present (Multi-resolution MAximum-entropy Reconstruction Technique Integrating Analytic Node), a new hybrid strong lensing (SL) modeling algorithm. By incorpor…
Joint JWST-DECam Lensing Reveals That the Bullet Cluster Is a Minor Merger
Boseong Young Cho, M. James Jee, Hyungjin Joo +2
We present the first robust virial masses of the Bullet Cluster's three individual components from a joint weak+strong lensing analysis combining JWST/NIRCam and DECam observations…
Mature but Still Growing: JWST Detection of the Earliest Intracluster Light at z ~ 2
Hyungjin Joo, M. James Jee, Kyle Finner +6
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. U…
Is Earendel a Star?: Investigating the Sunrise Arc Using JWST Strong and Weak Gravitational Lensing Analyses
Zachary P. Scofield, M. James Jee, Sangjun Cha +1
The galaxy cluster WHL J013719.8-08284 at exhibits a strong-lensing feature known as the Sunrise Arc, which hosts the candidate star Earendel at , the mo…
Reproducing Abell 2744 with the HyperMillennium Simulation
Qiao Wang, Ming Li, Liang Gao +11
We present the Hyper Millennium (HM) simulation, an extremely large cosmological simulation designed to support next-generation galaxy surveys. The simulation follows 4.2 trillion…
Weak-lensing Mass Reconstruction of Galaxy Clusters with a Convolutional Neural Network -- II: Application to Next-Generation Wide-Field Surveys
Sangjun Cha, M. James Jee, Sungwook E. Hong +3
Traditional weak-lensing mass reconstruction techniques suffer from various artifacts, including noise amplification and the mass-sheet degeneracy. In Hong et al. (2021), we demons…
SN H0pe: The First Measurement of from a Multiply-Imaged Type Ia Supernova, Discovered by JWST
Massimo Pascale, Brenda L. Frye, Justin D. R. Pierel +21
The first James Webb Space Telescope ({\it JWST}) Near InfraRed Camera (NIRCam) imaging in the field of the galaxy cluster PLCK G165.7+67.0 () uncovered a Type Ia supernova…
Weak-lensing mass bias in merging galaxy clusters
Wonki Lee, Sangjun Cha, M. James Jee +6
Although weak lensing (WL) is a powerful method to estimate a galaxy cluster mass without any dynamical assumptions, a model bias can arise when the cluster density profile departs…
MARS: A New Maximum Entropy-Regularized Strong Lensing Mass Reconstruction Method
Sangjun Cha, M. James Jee
Free-form strong-lensing (SL) mass reconstructions typically suffer from overfitting, which manifest itself as false-positive small-scale fluctuations. We present a new free-form M…
Weak-lensing Mass Reconstruction of Galaxy Clusters with Convolutional Neural Network
Sungwook E. Hong, Sangnam Park, M. James Jee +2
We introduce a novel method for reconstructing the projected matter distributions of galaxy clusters with weak-lensing (WL) data based on convolutional neural network (CNN). Traini…
A stellar dynamical mass measurement of an inactive black hole at redshift 2
Andrew B. Newman, Meng Gu, Sirio Belli +34
Supermassive black holes and their host galaxies grow together over time, producing correlations between the black hole mass and various galaxy properties. Determining the evolutio…
JWST Discovery of Strong Lensing from a Galaxy Cluster at Cosmic Noon: Giant Arcs and a Highly Concentrated Core of XLSSC 122
Kyle Finner, Sangjun Cha, Zachary P. Scofield +9
Our observations with the James Webb Space Telescope have made the remarkable discovery of strong gravitational lensing arcs from XLSSC 122 () - setting the record for the…
A High-Caliber View of the Bullet Cluster Through JWST Strong and Weak Lensing Analyses
Sangjun Cha, Boseong Young Cho, Hyungjin Joo +5
The Bullet Cluster (1E 0657-56) is a key astrophysical laboratory for studying dark matter, galaxy cluster mergers, and shock propagation in extreme environments. Using new JWST im…
Weak-lensing Analysis of Intracluster Filaments in Abell 2744: Matched-filter Scans and Stepwise 2D Tracing
Sangjun Cha, Kyle Finner, M. James Jee +1
We present a weak-lensing (WL) analysis of filamentary structures in the merging galaxy cluster Abell 2744 using wide-field Magellan/MegaCam imaging data. We employ two complementa…
Weak-Lensing Analysis of the Complex Cluster Merger Abell 746 with Subaru/Hyper Suprime-Cam
Kim HyeongHan, Hyejeon Cho, M. James Jee +15
The galaxy cluster Abell 746 (A746; =0.214), featuring a double radio relic system, two isolated radio relics, a possible radio halo, disturbed V-shaped X-ray emission, and intr…
Baryonic mass budgets in the central regions of the Bullet Cluster and their consistency with strong lensing in MOND
Dong Zhang, Hosein Haghi, Elena Asencio +8
Strong lensing observations of the Bullet Cluster have traditionally been regarded as strong evidence for dark matter and a major challenge to Milgromian dynamics (MOND). The offse…
Model-Independent Mass Reconstruction of the Hubble Frontier Field Clusters with MARS Based on Self-Consistent Strong Lensing Data
Sangjun Cha, M. James Jee
We present new strong-lensing (SL) mass reconstruction of the six Hubble Frontier Fields (HFF) clusters with the MAximum-entropy ReconStruction () algorithm. ${\tt MARS…
An Active Galaxy Cluster Merger at Cosmic Noon Revealed by JWST Weak Lensing and Multiwavelength Probes
Zachary P. Scofield, Kyle Finner, Hyungjin Joo +8
The galaxy cluster XLSSC~122 is a rare system at , hosting surprisingly evolved member galaxies when the Universe was only one-third of its present age. Leveraging deep J…
Weak-Lensing Detection of Intracluster Filaments in the Coma Cluster
Kim HyeongHan, M. James Jee, Sangjun Cha +1
Our concordance cosmological model predicts that galaxy clusters grow at the intersection of filaments structuring the cosmic web stretching tens of Mega parsecs. Although this hyp…
Precision MARS Mass Reconstruction of Abell 2744: Synergizing the Largest Strong Lensing and Densest Weak Lensing Datasets from JWST
Sangjun Cha, Kim HyeongHan, Zachary P. Scofield +2
We present a new high-resolution free-form mass model of Abell 2744, combining both weak-lensing (WL) and strong-lensing (SL) datasets from JWST. The SL dataset comprises 286 multi…