Intracluster light is a close tracer of the dark matter halo shape
Year: 2026
Type: article
Abstract: ABSTRACT We investigate whether the intracluster light (ICL) can serve as a reliable tracer of the shape of the underlying dark matter (DM) haloes in galaxy clusters. Using the cosmological Hydrangea cluster simulations, we measure the 3D and projected shapes of both components with a shape tensor computed in concentric ellipsoidal shells, out to the virial radius $R_\mathrm{200c}$ for each cluster. The ICL and DM are closely aligned, with their major axes typically offset from each other by $\lesssim$10 deg. Their axis ratios also match closely, with a typical difference of only $\approx \! 0.07$ for both the major-to-minor and major-to-intermediate axes, the DM being slightly rounder than the ICL. These trends are consistent across 2D and 3D measurements and agree well with results from isophotal fitting of mock images. In detail, the axis ratio offset is sensitive to the method used to remove satellites, and may also depend on the choice of subgrid physics models. We demonstrate that the ICL traces the DM shape better than the distribution of satellite galaxies, which exhibits larger scatter in the axis ratio and misalignment angle and is overall more elliptical. Together, these results indicate that the ICL can act as a useful proxy for DM halo ellipticity and orientation.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: National Science Foundation, Esperantic Studies Foundation, UK Research and Innovation, Leverhulme Trust, Durham University, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Gauss Centre for Supercomputing, Science and Technology Facilities Council, European Regional Development Fund, Agencia Estatal de Investigación, European Social Fund
Awards: Elektronenemission aus Kohlenstoff-Nanostrukturen II, Durham DiRAC-2 petascale facility, G1468651527, G1571591014, DiRAC-2.5 - the pathway to DiRAC Phase 3, G1857482063, G2126713887, G2262748287, G2309215924, G2368581224, G2820069179, G2843074508, G302750986, G3363198467, G3480869486, G3511845871, G403116508, G4251892262, G425668148, G4454001186, G4498713678, G451917667, G4655338613, G4831232377, G4848836895, G5385953647, G5967599077, G5976965613, G6033112984, G617610489, G6218905885, DiRAC-2.5 DC - Operations 2017-2020, G6996428894, G7084143925, Galaxy evolution in the cosmib web, G7208848743, G768801584, DiRAC: Memory Intensive 2.5y, G825883484, DiRAC: Memory Intensive 2.5x, Astronomy and Astrophysics at the University of Nottingham - 2023 to 2026
OpenAlex ID: W7142476562