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Search for steady and flaring neutrino emission from cosmic sources using the complete ANTARES dataset

ANTARES Collaboration, 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, F. Carenini, J. Carr, V. Carretero, T. Cartraud, S. Celli, L. Cerisy, M. Chabab, R. Cherkaoui El Moursli, 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, N. El Khayati, A. Enzenhöfer, P. Fermani, G. Ferrara, F. Filippini, L. Fusco, S. Gagliardini, J. García, C. Gatius Oliver, P. Gay, N. Geißelbrecht, H. Glotin, R. Gozzini, R. Gracia Ruiz, K. Graf, C. Guidi, L. Haegel, S. Hallmann, 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, J. A. Martínez-Mora, 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, V. Popa, 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

TL;DR

The paper conducts a comprehensive search for steady and flaring high-energy neutrino emission using the complete ANTARES dataset, applying an unbinned likelihood framework that combines spatial, energy, and temporal information under a power-law flux model. It performs a full-sky time-integrated scan, a Galactic Plane extended-source search, and a targeted candidate-list analysis, alongside time-dependent flare searches with Gaussian and Box temporal profiles. While no statistically significant neutrino sources are detected, the study reports the strongest full-sky hotspot post-trial of 0.38 and notable temporal overlaps with IceCube-detected flares, yielding a rare chance coincidence around 0.02% when considering multiple sources. The results place stringent upper limits and highlight intriguing, though not conclusive, multi-messenger connections between ANTARES and IceCube, underscoring the value of continued multi-wavelength and multi-messenger follow-ups. Key analytical components include the flux model $ \frac{d\phi_ν}{dE} = Φ^{ν+\barν}_{1\mathrm{GeV}} (E_ν / 1\mathrm{GeV})^{-\gamma} $, the PSF-based spatial PDFs, and time-profile PDFs for flares, all evaluated across a dense sky grid with proper trial-factor corrections via pseudo-experiments.

Abstract

ANTARES, a neutrino detector located in the depths of the Mediterranean Sea, operated successfully for over 15 years before being decommissioned in 2022. The telescope offered an ideal vantage view of the Southern Sky and benefited from optimal water properties for enhanced angular resolution. This study makes use of data collected over the entire operational period of ANTARES to search for sources of high-energy cosmic neutrinos, considering both steady and flaring emission scenarios. First, a time-integrated search for high-energy neutrino clustering across the celestial sphere is conducted. The most significant accumulation is found at coordinates $(α, δ) =(200.5^\circ\, 17.7^\circ)$ with a post-trial p-value equal to 0.38. A dedicated search in the Galactic Plane is also performed for extended sources, yielding no significant excess. Additionally, a list of potential neutrino sources are investigated. The blazar MG3 J225517+2409 is identified as the most significant object, yet the excess remains compatible with background fluctuations. A mild local excess of 2.4$σ$ is found for the blazar TXS 0506+056. The full sky is also examined for the presence of flaring neutrino emissions. The most significant excess in this case corresponds to a $\sim$4-day flare from the direction $(α, δ) = (141.3^\circ\, 9.8^\circ)$, with a post-trial p-value of 0.30. Finally, the directions of sources highlighted in IceCube's time-dependent searches are investigated. Temporal overlaps between ANTARES and IceCube flares are identified for PKS 1502+106 and TXS 0506+056, with an estimated chance probability of about 0.02%, making this observation particularly noteworthy.

Search for steady and flaring neutrino emission from cosmic sources using the complete ANTARES dataset

TL;DR

The paper conducts a comprehensive search for steady and flaring high-energy neutrino emission using the complete ANTARES dataset, applying an unbinned likelihood framework that combines spatial, energy, and temporal information under a power-law flux model. It performs a full-sky time-integrated scan, a Galactic Plane extended-source search, and a targeted candidate-list analysis, alongside time-dependent flare searches with Gaussian and Box temporal profiles. While no statistically significant neutrino sources are detected, the study reports the strongest full-sky hotspot post-trial of 0.38 and notable temporal overlaps with IceCube-detected flares, yielding a rare chance coincidence around 0.02% when considering multiple sources. The results place stringent upper limits and highlight intriguing, though not conclusive, multi-messenger connections between ANTARES and IceCube, underscoring the value of continued multi-wavelength and multi-messenger follow-ups. Key analytical components include the flux model , the PSF-based spatial PDFs, and time-profile PDFs for flares, all evaluated across a dense sky grid with proper trial-factor corrections via pseudo-experiments.

Abstract

ANTARES, a neutrino detector located in the depths of the Mediterranean Sea, operated successfully for over 15 years before being decommissioned in 2022. The telescope offered an ideal vantage view of the Southern Sky and benefited from optimal water properties for enhanced angular resolution. This study makes use of data collected over the entire operational period of ANTARES to search for sources of high-energy cosmic neutrinos, considering both steady and flaring emission scenarios. First, a time-integrated search for high-energy neutrino clustering across the celestial sphere is conducted. The most significant accumulation is found at coordinates with a post-trial p-value equal to 0.38. A dedicated search in the Galactic Plane is also performed for extended sources, yielding no significant excess. Additionally, a list of potential neutrino sources are investigated. The blazar MG3 J225517+2409 is identified as the most significant object, yet the excess remains compatible with background fluctuations. A mild local excess of 2.4 is found for the blazar TXS 0506+056. The full sky is also examined for the presence of flaring neutrino emissions. The most significant excess in this case corresponds to a 4-day flare from the direction , with a post-trial p-value of 0.30. Finally, the directions of sources highlighted in IceCube's time-dependent searches are investigated. Temporal overlaps between ANTARES and IceCube flares are identified for PKS 1502+106 and TXS 0506+056, with an estimated chance probability of about 0.02%, making this observation particularly noteworthy.

Paper Structure

This paper contains 12 sections, 10 equations, 8 figures, 1 table.

Table of Contents

  1. Introduction
  2. The ANTARES neutrino telescope and data sample
  3. Analysis method
  4. Time-integrated approach
  5. Time-dependent approach
  6. Results of the time-integrated studies
  7. Full-sky search
  8. Galactic Plane scan
  9. Candidate list search
  10. Results of the time-dependent searches
  11. Conclusions
  12. Appendix

Figures (8)

  • Figure 1: Sky map in equatorial coordinates of pre-trial p-values found in the search for point-like neutrino sources over the full ANTARES visible sky. The blue box indicates the location with the highest significance.
  • Figure 2: Left: Pre-trial p-value map around the location of the full-sky most significant excess. Right: Distribution of the ANTARES events close to this region. The inner (outer) solid green line depicts the one (five) degree distance from the position of the hotspot. The red points denote shower-like events, whereas the blue points indicate track-like events. The dashed circles around the events indicate the angular error estimate. Different tones of red and blue correspond to the values assumed by the energy estimators as shown in the legend. The location and names of the three astrophysical sources located closer than 2.0$^\circ$ from the hotspot are shown in golden.
  • Figure 3: Colour map of the obtained pre-trial p-values at each of the analysed locations of the Galactic Plane. The presence of a source with a Gaussian width of $1.0^\circ$ has been assumed in the likelihood. Most of the directions between $70^\circ$ and $170^\circ$ in the Galactic longitude are not accessible as they produce only downgoing events in the ANTARES detector.
  • Figure 6: Left: Pre-trial p-value map around the location of the most significant source MG3 J225517+2409 for $\gamma = 2.0$. Right: Distribution of the ANTARES events close to MG3 J225517+2409. A detailed description of the map is given in the caption of Figure \ref{['fig:hotspotevents']}.
  • Figure 7: Distribution of the ANTARES events close to (a) Vela X, with the magenta dashed line indicating the Gaussian extension assumed in the analysis, and to (b) TXS 0506+056. A detailed description of the map is given in the caption of Figure \ref{['fig:hotspotevents']}.
  • ...and 3 more figures