Dwarf Galaxy Reticulum II's MeerKAT L-Band Observation: Constraining WIMP Dark Matter
Abstract
The nature of dark matter remains one of the most profound open questions in modern physics, with weakly interacting massive particles (WIMPs) among the leading candidates proposed to account for the observed anomalies across cosmic scales. If WIMPs annihilate or decay in the dense dark matter haloes of nearby galaxies, the resulting high-energy electrons/positrons can produce synchrotron radiation in the presence of ambient magnetic fields, yielding a potentially detectable radio signature. Dwarf spheroidal galaxies are particularly promising targets for indirect dark matter searches due to their high mass-to-light ratios and low astrophysical foreground contamination. While radio observations have been widely used to constrain WIMP properties in these systems, the resulting limits remain highly sensitive to poorly constrained magnetic field assumptions. Here we utilize L-band ($1.3−−1.5$ GHz) observations from the MeerKAT array directed towards dwarf galaxy Reticulum II and measure the surface brightness profile across the dwarf galaxy. Combining these measurements with theoretical models of WIMP annihilation and yield 95% confidence level upper limits on the WIMP annihilation cross-section ⟨σv⟩ ≲ 10−26 cm3 s−1 for masses mχ∼ 10-$200$ GeV (with the assumed uniform magnetic field model and diffusion constant). As next-generation radio facilities such as the Square Kilometre Array come online, robust characterisation of magnetic environments in dwarf galaxies will be essential to fully exploit their sensitivity to the particle nature of dark matter.
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BibTeX
@misc{badenhorst2026dwarf,
title = {{Dwarf Galaxy Reticulum II's MeerKAT L-Band Observation: Constraining WIMP Dark Matter}},
author = {Phillip Badenhorst and Michael Sarkis and Yin-Zhe Ma and Wen-Qing Guo and Geoff Beck and Qiang Yuan and Gyula I. G. Jozsa and Steven G. Murray},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.39752},
eprint = {2610.39752},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.39752},
}
RIS
TY - UNPB
TI - Dwarf Galaxy Reticulum II's MeerKAT L-Band Observation: Constraining WIMP Dark Matter
AU - Phillip Badenhorst
AU - Michael Sarkis
AU - Yin-Zhe Ma
AU - Wen-Qing Guo
AU - Geoff Beck
AU - Qiang Yuan
AU - Gyula I. G. Jozsa
AU - Steven G. Murray
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.39752
UR - https://arxiv.org/abs/2610.39752
AB - The nature of dark matter remains one of the most profound open questions in modern physics, with weakly interacting massive particles (WIMPs) among the leading candidates proposed to account for the observed anomalies across cosmic scales. If WIMPs annihilate or decay in the dense dark matter haloes of nearby galaxies, the resulting high-energy electrons/positrons can produce synchrotron radiation in the presence of ambient magnetic fields, yielding a potentially detectable radio signature. Dwarf spheroidal galaxies are particularly promising targets for indirect dark matter searches due to their high mass-to-light ratios and low astrophysical foreground contamination. While radio observations have been widely used to constrain WIMP properties in these systems, the resulting limits remain highly sensitive to poorly constrained magnetic field assumptions. Here we utilize L-band ($1.3−−1.5$ GHz) observations from the MeerKAT array directed towards dwarf galaxy Reticulum II and measure the surface brightness profile across the dwarf galaxy. Combining these measurements with theoretical models of WIMP annihilation and yield 95% confidence level upper limits on the WIMP annihilation cross-section ⟨σv⟩ ≲ 10^−26 cm^3 s^−1 for masses m_χ∼ 10-$200$ GeV (with the assumed uniform magnetic field model and diffusion constant). As next-generation radio facilities such as the Square Kilometre Array come online, robust characterisation of magnetic environments in dwarf galaxies will be essential to fully exploit their sensitivity to the particle nature of dark matter.
ER -