⚛️ phenomenology

Search for dark matter annihilation in the Sun using the full ANTARES dataset

Using the full ANTARES dataset from 2007 to 2022, this study found no significant evidence for dark matter annihilation in the Sun, thereby establishing improved upper limits on WIMP-proton interaction cross sections for masses between 35 GeV and 10 TeV that are consistent with other direct and indirect dark matter searches.

Original authors: A. Albert, S. Alves, M. André, M. Ardid, S. Ardid, J. -J. Aubert, J. Aublin, B. Baret, S. Basa, Y. Becherini, B. Belhorma, F. Benfenati, V. Bertin, S. Biagi, J. Boumaaza, M. Bouta, M. C. Bouwhuis, H.

Published 2026-09-30

📖 3 min read🧠 Deep dive

CC BY 4.0

Original authors: A. Albert, S. Alves, M. André, M. Ardid, S. Ardid, J. -J. Aubert, J. Aublin, B. Baret, S. Basa, Y. Becherini, B. Belhorma, F. Benfenati, V. Bertin, S. Biagi, J. Boumaaza, M. Bouta, M. C. Bouwhuis, H. Brânzaş, R. Bruijn, J. Brunner, J. Busto, B. Caiffi, D. Calvo, S. Campion, A. Capone, L. Caramete, F. Carenini, J. Carr, V. Carretero, T. Cartraud, S. Celli, M. Chabab, T. Chiarusi, M. Circella, J. A. B. Coelho, A. Coleiro, R. Coniglione, P. Coyle, A. Creusot, A. F. Díaz, B. De Martino, C. Distefano, I. Di Palma, C. Donzaud, D. Dornic, D. Drouhin, T. Eberl, A. Eddymaoui, T. van Eeden, D. van Eijk, S. El Hedri, A. Enzenhöfer, P. Fermani, G. Ferrara, F. Filippini, L. A. Fusco, S. Gagliardini, J. García-Méndez, C. Gatius Oliver, P. Gay, N. Geißelbrecht, H. Glotin, R. Gozzini, R. Gracia Ruiz, K. Graf, C. Guidi, L. Haegel, H. van Haren, A. J. Heijboer, Y. Hello, L. Hennig, J. J. Hernández-Rey, J. Hößl, F. Huang, G. Illuminati, B. Jisse-Jung, M. de Jong, P. de Jong, M. Kadler, O. Kalekin, U. Katz, A. Kouchner, I. Kreykenbohm, V. Kulikovskiy, R. Lahmann, M. Lamoureux, A. Lazo, D. Lefèvre, E. Leonora, G. Levi, S. Le Stum, S. Loucatos, J. Manczak, M. Marcelin, A. Margiotta, A. Marinelli, P. Migliozzi, A. Moussa, R. Muller, S. Navas, E. Nezri, B. Ó Fearraigh, E. Oukacha, A. M. Păun, G. E. Păvălaş, S. Peña-Martínez, M. Perrin-Terrin, P. Piattelli, C. Poirè, T. Pradier, N. Randazzo, D. Real, G. Riccobene, A. Romanov, A. Sánchez Losa, A. Saina, F. Salesa Greus, D. F. E. Samtleben, M. Sanguineti, P. Sapienza, F. Schüssler, J. Seneca, M. Spurio, Th. Stolarczyk, M. Taiuti, Y. Tayalati, B. Vallage, G. Vannoye, V. Van Elewyck, S. Viola, D. Vivolo, J. Wilms, S. Zavatarelli, A. Zegarelli, J. D. Zornoza, J. Zúñiga

Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

For decades, astronomers have known that the visible stars and galaxies make up only a small fraction of the universe. The rest is an invisible substance called dark matter, which exerts gravity but does not emit or reflect light. While we cannot see it directly, its presence is felt in the way galaxies spin and how light bends around massive objects. One leading theory suggests that dark matter is made of heavy, slow-moving particles that rarely interact with ordinary matter. If these particles exist, they might occasionally collide with the nuclei of atoms inside massive objects like the Sun. When this happens, the particles could get trapped by the Sun's gravity, sinking to the core where they might collide with each other and vanish, releasing energy in the form of other particles, including neutrinos. These ghostly particles travel through space at nearly the speed of light, passing through planets and stars without stopping, carrying a message from the Sun's center to Earth.

A team of scientists working with the ANTARES neutrino telescope, located deep in the Mediterranean Sea, set out to listen for this message. The telescope, which operated from 2007 until 2022, consisted of a vast three-dimensional array of light sensors suspended in the dark water. Its job was to catch the faint flashes of blue light produced when a high-energy neutrino from space struck an atom in the water, creating a charged particle that moved faster than light can travel in water. By analyzing the full dataset collected over fifteen years, the researchers looked specifically for an excess of these neutrinos coming from the direction of the Sun. They were searching for a signal that would prove dark matter particles are indeed being captured and annihilating in our star's core.

The analysis covered a wide range of possible dark matter masses, from 35 GeV/c² up to 10 TeV/c², and considered several different ways these particles might annihilate. The team used sophisticated computer models to predict what the signal should look like and compared it against the background noise of neutrinos created by cosmic rays hitting the Earth's atmosphere. After carefully filtering the data and applying strict selection criteria to ensure the detected particles were truly coming from the Sun, the result was clear: there was no significant excess of neutrinos. The number of events observed matched exactly what would be expected from natural background sources alone.

Because no signal was found, the researchers could not confirm the existence of dark matter particles in the Sun, but they did achieve something equally important for science: they set new, stricter limits on how these particles might behave. By ruling out certain possibilities, they narrowed the search space for future experiments. The study determined that if these dark matter particles do exist, they interact with protons in the Sun even less frequently than previously thought. These new limits are two to three times more sensitive than those achieved by the same team in earlier studies, thanks to the much larger amount of data and improved methods for reconstructing the paths of low-energy particles. The findings are consistent with results from other experiments looking for dark matter, both those searching for direct collisions in underground laboratories and those looking for indirect signals in space. While the Sun remains silent on this specific question, the absence of a signal helps physicists refine their theories and guides the next generation of detectors as they continue the hunt for the invisible substance that holds the universe together.

Technical Summary: Search for Dark Matter Annihilation in the Sun using the Full ANTARES Dataset

Problem Statement
Weakly Interacting Massive Particles (WIMPs) remain a leading candidate for particle dark matter. In scenarios where WIMPs are gravitationally captured by massive celestial bodies, they may accumulate in the core and annihilate into Standard Model particles, producing high-energy neutrinos. The Sun, moving through the Galactic dark matter halo, acts as a potential trap for these particles. The primary challenge in detecting this signal is distinguishing a potential neutrino excess from the dominant background of atmospheric muons and atmospheric neutrinos. Previous searches by the ANTARES Collaboration utilized limited datasets; this work aims to maximize sensitivity by analyzing the full operational dataset of the ANTARES neutrino telescope.

Methodology
The analysis utilizes the complete dataset recorded by the ANTARES neutrino telescope in the Mediterranean Sea from February 2007 to February 2022, corresponding to an effective livetime of 12.47 years (4,551 days).

Detector and Event Reconstruction: ANTARES detects Cherenkov light from secondary charged particles produced by neutrino interactions. To optimize sensitivity across different energy ranges, three distinct reconstruction strategies were employed:
1. Method 1: Deep learning models for events with hits on a single line, targeting low-energy neutrinos (<100 GeV).
2. Method 2: A $\chi^2$ -like fit for intermediate energies, utilizing residuals between expected and measured photon arrival times.
3. Method 3: A maximum likelihood method for high energies (>500 GeV), offering superior angular resolution.
  For each WIMP mass and annihilation channel, the strategy providing the best sensitivity was selected.
Signal and Background Modeling: The analysis focuses on up-going muon tracks to reject atmospheric muons. The background is estimated by scrambling the time information of events, leveraging the Sun's motion to distinguish a static source signal from the isotropic atmospheric neutrino background. The signal hypothesis assumes WIMP annihilation in the Sun's core, simulated using WimpSim software. Three benchmark annihilation channels were considered with 100% branching ratios: $b\bar{b}$ , $\tau^+\tau^-$ , and $W^+W^-$ .
Statistical Approach: An extended maximum-likelihood approach was used, treating the number of signal events ( $n_s$ ) as a free parameter. The Test Statistic (TS) was defined as the likelihood ratio between the best-fit signal+background hypothesis and the background-only hypothesis. The analysis was blinded until all selection cuts and optimization procedures were finalized using simulations and scrambled data.

Key Contributions

Dataset Expansion: This work triples the amount of data analyzed compared to previous ANTARES searches for solar dark matter, covering the full operational history of the detector.
Optimized Reconstruction: The implementation of a multi-strategy reconstruction approach (deep learning, $\chi^2$ , and maximum likelihood) allows for tailored sensitivity across a wide mass range (35 GeV/ $c^2$ to 10 TeV/ $c^2$ ).
Comprehensive Limits: The study derives upper limits on the WIMP-proton interaction cross-section for both spin-dependent (SD) and spin-independent (SI) interactions across the specified mass range and for the three annihilation channels.

Results

Signal Observation: No significant excess of neutrinos from the direction of the Sun was observed. The number of fitted signal events ( $\hat{n}_s$ ) for all tested masses and channels was compatible with background expectations within statistical uncertainties (p-values ranged from 0.08 to 0.24).
Flux and Cross-Section Limits: Upper limits at the 90% confidence level (CL) were established for the neutrino flux and the WIMP-nucleon scattering cross-section.
- For spin-dependent interactions, the derived limits are competitive with, and in the mass region above 100 GeV/ $c^2$ more stringent than, those from direct detection experiments (e.g., PICO-60, LZ).
- For spin-independent interactions, direct detection experiments (e.g., XENONnT) currently provide more stringent limits, though the ANTARES results offer complementary constraints.
Comparison with Other Experiments: The results are consistent with limits from other neutrino telescopes (IceCube, Super-Kamiokande) and direct detection experiments. The paper notes that differences in limits between ANTARES and IceCube can be partially attributed to the use of different simulation tools (WimpSim vs. $\chi$ aron) for neutrino spectra.

Significance and Claims
The paper claims that these results improve upon previous ANTARES publications by a factor of two to three, primarily due to the increased livetime and improved reconstruction techniques for low-energy events. The study provides robust upper bounds on the dark matter annihilation cross-section in the Sun over a large mass range. While no discovery was made, the results serve to constrain theoretical dark matter models, particularly those predicting spin-dependent interactions, and demonstrate the complementary nature of indirect detection (neutrino telescopes) and direct detection experiments in the search for dark matter. The findings are consistent with null results reported by other major experiments in the field.

Technical Summary: Search for Dark Matter Annihilation in the Sun using the Full ANTARES Dataset

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