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 a vantage view of the Southern Sky and benefited from favourable water properties, enabling good 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 much of the celestial sphere is conducted. The most significant accumulation is found at coordinates (α , δ ) =(200.5^∘, 17.7^∘ ) 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 is 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 emission. The most significant excess in this case corresponds to a ∼ 4-day flare from the direction (α , δ ) = (141.3^∘, 9.8^∘ ) , 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

Context. Most long gamma-ray bursts (GRBs) exhibit afterglows that are broadly consistent with external forward-shock emission, which is typically described by smooth broken power-law decays in the multiband light curve. However, a minority of well-sampled GRBs deviates from this behavior, including the GRB we investigated, GRB 250129A. This source shows multiple late-time rebrightenings at X-ray and optical wavelengths. Rebrightenings are often attributed to energy injection from prolonged activity of the central engine, refreshed shocks from delayed shell collisions, density jumps in the ambient medium, or to the angular jet structure and viewing-angle effects. Aims After a comprehensive analysis of the prompt emission of the GRB observed in gamma rays and in the near-infrared, we investigated the physical origin of the multiple X-ray and optical flaring episodes observed in GRB 250129A. Methods. We conducted comprehensive temporal and spectral multiband analyses of GRB 250129A. The physical processes at play in the afterglow light curves were investigated using several methods, ranging from empirical fitting to Bayesian inference. The high-quality monitoring of the flare episodes, together with the connection between the prompt emission and the afterglow, enabled us to test the consistency of the fireball model and to constrain, reject, or confirm alternative scenarios. Results. GRB 250129A is an interesting GRB with multiwavelength prompt and afterglow emission. By conducting the prompt and time-resolved analyses, we obtained an isotropic-equivalent energy of Eiso, γ = (1.35 ± 0.12)×1053 erg. By modeling the afterglow using an agnostic Bayesian framework (NMMA), we ruled out a single external-shock evolution and a one-time energy-injection scenario. By further performing numerical calculations, we demonstrated that the rebrightening episodes are consistent with refreshed shocks arising from delayed collisions between relativistic shells. This agrees with evolving outflow dynamics. Conclusions. Based on the consistency between our analyses of the prompt and afterglow GRB 250129A data, together with prior general knowledge on microphysical properties, we find that two statistically significant rebrightening episodes occurred within 1.1 days post trigger and can be explained by a sequence of refreshed shocks. We stress that the availability of temporally and spectrally rich GRB datasets, such as the one we present here, provides a powerful means to test current modeling frameworks.

The diffuse emission of gamma-rays and neutrinos, produced by interactions of cosmic rays with interstellar matter in the Milky Way, provides valuable insights into cosmic ray propagation and Galactic processes. Emission models incorporating different assumptions about cosmic ray diffusion, source distribution, and target gas density are tested using data from neutrino telescopes. In this study, the final all-flavor neutrino dataset, collected over 15 years (2007-2022) by the ANTARES neutrino telescope, is analyzed. A maximum likelihood ratio method built to handle templates of Galactic emission models is employed to evaluate the compatibility of these models with the observed spatial and energy distributions of neutrino events. The results do not yield stringent constraints on the tested models and upper limits on the diffuse neutrino flux are derived, which are compatible with the results obtained by other experiments.

This study presents a search for magnetic monopoles using the full ANTARES dataset collected over 14 years (2008-2022). The interaction of monopoles with matter was modeled according to the Kazama, Yang and Goldhaber cross-section, and dedicated reconstruction strategies were applied to probe velocities both above and below the Cherenkov threshold. No signal consistent with monopoles was found. We derive 90% C.L. upper limits on the flux of relativistic monopoles at the level of 10-18 cm-2 s-1 sr-1, improving upon previous ANTARES results and confirming those obtained by IceCube and other neutrino telescopes. These results constitute the final contribution of ANTARES to the search for magnetic monopoles.

PROVIDENCE is an ONERA-led project to install a new-generation optical ground station at the Haute-Provence Observatory (OHP) in South of France. Built around a 2.5-meter aperture, the station addresses five core science cases: space domain awareness, astronomy, laser activities and communications, atmospheric characterization, and instrumental prototyping. The project is organized into three parallel subprojects covering the telescope (Providence T), the building (Providence B), and the instruments (Providence I), the latter including the facility's first-light adaptive optics instrument, INTERSTELLAR. This paper presents the scientific motivation, the project architecture, the telescope technical specifications, the civil-engineering challenges associated with replacing the existing T152 equatorial telescope, and the station layout designed to host multiple co-active instrument teams. The project roadmap targets First Light in 2029, timed to track the close-approach flyby of asteroid Apophis.

Gamma-Ray Burst GRB 241030A (z = 1.411) exhibited a bright afterglow (similar to GRB 221009A), detected across gamma-ray, X-ray, UV, and optical bands, providing a probe of GRB afterglow physics. We compiled multi-wavelength observations spanning from a minute to a week after the prompt emission, processing the data through a unified photometry pipeline. We analysed the observations both analytically and using Bayesian inference with two independent models. Our models assume that the afterglow emission arises from the strong forward shock of a laterally structured jet, with possible contributions from synchrotron self-Compton (SSC) scatterings. Our models reproduce X-ray to optical data, favouring a jet propagating into a constant-density interstellar medium, with a viewing angle within the jet core. However, both analyses require parameter values that are extreme compared to expectations from standard theory. In particular, our results imply extremely energetic jets despite regular prompt energy, leading to a very inefficient prompt emission. Furthermore, the jets are inefficient at accelerating particles, with low electron and magnetic energy fractions, leading to significant SSC emission. Our analyses indicate that the jets have large opening angles and propagate in high-density media. If the afterglow is indeed powered by radiation emitted behind a strong forward shock, our results place GRB 241030A within a sub-class of GRBs characterised by extreme kinetic energies, large jet opening angles, and very low prompt emission efficiencies, with strong SSC radiation. These predictions are difficult to reconcile with typical expectations from other GRBs. We therefore suggest that the afterglow of GRB 241030A is not solely powered by forward shock emission.

We present the organisation and early results from the Observatory Science program of the Space-based multi-band astronomical Variable Objects Monitor (SVOM), based on data collected between July 2024 and December 2025. Although primarily designed for gamma-ray burst studies, SVOM's wide-field, multi-wavelength instruments enable a broad range of high-energy astrophysical investigations. We summarize the execution and performance of the General Program and Target-of-Opportunity observations, and we describe the frameworks used for serendipitous source detection and monitoring with the ECLAIRs coded-mask instrument. Over this period, SVOM carried out more than a thousand pointed observations and detected several hundred non-GRB high-energy sources, mainly X-ray binaries, as well as blazars, stellar flares, magnetars, and unidentified events. We highlight some key results, including the monitoring of the microquasar Cygnus X-1, the detection of burst oscillations from the Low-Mass X-ray Binary 4U 0614+091, the spectral-state monitoring of Aql X-1, the first SVOM detection of an X-ray blazar flare from 1ES 1959+650, and observations of a stellar flare from HD 22468. These results demonstrate SVOM's strong capabilities for time-domain astrophysics beyond its core GRB program.

Following its launch on 22 June 2024, the Space-based multi-band astronomical Variable Objects Monitor (SVOM) successfully completed its flight acceptance, commissioning, and scientific validation phases in early 2025, during which several tens of gamma-ray bursts (GRBs) were detected onboard. Three quarters of these events have also been detected by other satellites, and a quarter are SVOM-only GRBs. In this article, we describe these early GRB observations, with a first description of the SVOM GRB sample that is emerging, and of the level of characterisation already achieved, and with a focus on a few events of particular interest. These early results are very encouraging regarding SVOM's ability to detect and fully characterise (including prompt emission, afterglow and distance) a wide range of GRBs (classical long GRBs, short GRBs, X-Ray Flashes, etc.) and to enable the use of these extreme high-energy transients as probes of the distant Universe.

We present the N-fit algorithm designed to improve the reconstruction of neutrino events detected by a single line of the ANTARES underwater telescope, usually associated with low energy neutrino events (similar to 100 GeV). N-Fit is a neural network model that relies on deep learning and combines several advanced techniques in machine learning-deep convolutional layers, mixture density output layers, and transfer learning (TL). This framework divides the reconstruction process into two dedicated branches for each neutrino event topology-tracks and showers-composed of sub-models for spatial estimation-direction and position-and energy inference, which later on are combined for event classification. Regarding the direction of single-line (SL) events, the N-Fit algorithm significantly refines the estimation of the zenithal angle, and delivers reliable azimuthal angle predictions that were previously unattainable with traditional chi 2-fit methods. Improving on energy estimation of SL events is a tall order; N-Fit benefits from TL to efficiently integrate key characteristics, such as the estimation of the closest distance from the event to the detector. N-Fit also takes advantage from TL in event topology classification by freezing convolutional layers of the pretrained branches. Tests on Monte Carlo simulations and data demonstrate a significant reduction in mean and median absolute errors across all reconstructed parameters. The improvements achieved by N-Fit highlight its potential for advancing multimessenger astrophysics and enhancing our ability to probe fundamental physics beyond the Standard Model using SL events from ANTARES data.

COLIBRI, the French Mexican Ground Followup Telescope (FM GFT) for SVOM, is a 1.3 meter rapid response optical facility specifically developed for prompt, multiband observations of GRB afterglows and for delivering subarcsecond localisations of optical counterparts for detailed followup studies. The telescope operates through a fully automated system that manages the entire workflow, from alert reception to counterpart identification. Commissioning results confirm that the telescope meets design specifications, and this paper presents a comprehensive performance assessment of the capabilities.

The SVOM (Space-based Variable Objects Monitor) mission, launched into low Earth orbit on 22 June 2024, is a French-Chinese multi-wavelength observatory dedicated to the study of the transient sky. Inspired by the Neil Gehrels Swift Observatory, it consists of an autonomous rapid-slewing satellite, linked in real time to several ground-based telescopes. The space segment comprises two X-ray/gamma-ray wide-field instruments (ECLAIRs and GRM) with real-time triggering capabilities combined with two narrow-field telescopes in X-ray (MXT) and in visible (VT). In addition, the SVOM collaboration has also developed a unique visible and NIR ground-based follow-up system to promptly respond to the gamma-ray transients detected on board. The core program of SVOM will provide new insights into the Gamma-Ray Burst physics by providing a homogeneous dataset covering both the prompt and afterglow emissions, as well as better studying the low luminosity and soft Gamma-Ray Burst populations. As a versatile satellite platform with fast slewing capabilities, SVOM also comprises a Target of Opportunity program and a General Program consisting in pointed observations scheduled over the year that will both significantly contribute to the multi-messenger and time-domain astronomy.

Context. Gamma-ray burst GRB 241030A (z = 1.411) exhibited a particularly bright afterglow (similar to the 'BOAT', GRB 221009A), detected across gamma-ray, X-ray, UV, and optical bands. The extensive, multi-wavelength observations of this remarkable event provide a valuable opportunity to advance our understanding of GRB afterglow physics. Aims. We aim to constrain the physical properties of the jet, its microphysics, and the characteristics of the circumburst environment in the context of forward-shock emission. Methods. We compiled multi-wavelength observations spanning from a minute to a week after the prompt emission, processing the data through a unified photometry pipeline. Leveraging this comprehensive dataset, we analysed the observations both analytically and using Bayesian inference with two independent models. Our models assume that the afterglow emission arises from the strong forward shock of a laterally structured jet, with possible contributions from synchrotron self-Compton (SSC) scatterings. Results. We find that our models do reproduce the afterglow observations accurately, from the X-rays to the optical, favouring a jet propagating into a constant-density interstellar medium, with a viewing angle within the jet core. However, both analyses - with and without the inclusion of SSC scatterings - require parameter values that are extreme compared to expectations from standard theory. In particular, our results imply extremely energetic jets despite regular prompt energy, leading to a very inefficient prompt emission. Furthermore, the jets are particularly inefficient at accelerating particles, with low & varepsilon;(e) and & varepsilon;(B), leading to significant SSC emission. Finally, our analyses indicate that the jets have large opening angles and propagate in high-density media. Conclusions. If the afterglow is indeed powered by radiation emitted behind a strong forward shock, our results place GRB 241030A within a sub-class of GRBs characterised by extreme kinetic energies, large jet opening angles, and very low prompt emission efficiencies, below 10(-3), with strong SSC radiation. These predictions are difficult to reconcile with typical expectations from other GRBs. We therefore suggest that the afterglow of GRB 241030A is not solely powered by forward shock emission, and we discuss other options such as a long-lasting reverse-shock contribution.

Position calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infrastructure. The ANTARES neutrino telescope operated from 2006 until 2022 in the Mediterranean Sea at a depth exceeding 2000 m. It comprised nearly 900 glass spheres with 432 mm diameter and 15 mm thickness, equipped with photomultiplier tubes to detect Cherenkov light from tracks of charged elementary particles. In an experimental setup within ANTARES, piezo sensors have been glued to the inside of such – otherwise empty – glass spheres. These sensors recorded signals from acoustic emitters with frequencies from 46545 to 60235 Hz. Two waves propagating through the glass sphere are found as a result of the excitation by the waves in the water. These can be qualitatively associated with symmetric and asymmetric Lamb-like waves of zeroth order: a fast (early) one with v_e ≈ 5 mm/μs and a slow (late) one with v_ℓ≈ 2 mm/μs . Taking these findings into account improves the accuracy of the position calibration. The results can be transferred to the KM3NeT neutrino telescope, currently under construction at multiple sites in the Mediterranean Sea, for which the concept of piezo sensors glued to the inside of glass spheres has been adapted for monitoring the positions of the photomultiplier tubes.

Interest for studying cosmic neutrinos using deep-sea detectors has increase after the discovery of a diffuse flux of cosmic neutrinos by the IceCube collaboration and the possibility of wider multi-messenger studies with the observations of gravitational waves. The ANTARES detector was the first neutrino telescope in seawater, operating successfully in the Mediterranean Sea for more than a decade and a half. All challenges related to the operation in the deep sea were accurately addressed by the collaboration. Deployment and connection operations became smoother over time; data taking and constant re-calibration of the detector due to the variable environmental conditions were fully automated. A wealth of results on the subject of astroparticle physics, particle physics and multi-messenger astronomy have been obtained, despite the relative modest size of the detector, paving the way to a new generation of larger undersea detectors. This review summarizes the efforts by the ANTARES collaboration that made the possibility to operate neutrino telescopes in seawater a reality and the results obtained in this endeavor.

Most long Gamma-ray bursts originate from a rare type of massive stellar explosion. Their afterglows, while rapidly fading, can be initially extremely luminous at optical/near-infrared wavelengths, making them detectable at large cosmological distances. Here we report the detection and observations of GRB 250314A by the SVOM satellite and the subsequent follow-up campaign with the near-infrared afterglow discovery and the spectroscopic measurements of its redshift z ≃ 7.3 . This burst happened when the Universe was only ∼ 5

Most long gamma-ray bursts (LGRBs) originate from a rare type of massive stellar explosion. Their afterglows, while rapidly fading, can initially be extremely luminous at optical and near-infrared wavelengths, making them detectable at large cosmological distances. Here we report the detection and observations of GRB 250314A by the SVOM satellite and the subsequent follow-up campaign that led to the discovery of the near-infrared afterglow and spectroscopic measurements of its redshift z similar or equal to 7.3. This burst occurred when the Universe was only about 5% of its current age. We discuss the signature of these rare events within the context of the SVOM operating model and the ways to optimise their identification with adapted ground follow-up observation strategies.

Context. Transient sky astronomy is entering a new era with the advent of the Space Variable Objects Monitor mission (SVOM), successfully launched on 22 June 2024. The primary goal of SVOM is to monitor the hard X-ray sky searching for gamma-ray bursts (GRBs). On top of its on-board follow-up capabilities, SVOM will be backed by its ground segment composed of several facilities, including the near-infrared (NIR) imager CAGIRE. Mounted on the robotic telescope COLIBRI, it will be a unique instrument capable of performing fast follow-up of GRB afterglows in the J and H bands, ideal for capturing high-redshift (z>6) and/or obscured GRBs. Aims. This paper is aimed at estimating the performances of CAGIRE for GRB NIR afterglow detection based on the characteristics of the detector and the specificities of the COLIBRI telescope. Quickly fading GRB afterglows pose challenges that should be addressed by adapting observing strategies to the capabilities of CAGIRE. Methods. We used an end-to-end image simulator to produce realistic CAGIRE images, taking into account the results from the characterisation of the ALFA detector used by CAGIRE. We implemented a GRB afterglow generator that simulates infrared light curves and spectra based on published observation of distant GRBs (z>6). Results. We retrieved the photometry of nine GRB afterglows in various scenarios covered by CAGIRE. Capturing afterglows as early as one minutes after the burst allows for the identification of a NIR counterpart in the brightest four events. When artificially redshifted even further away, these events remain detectable by CAGIRE up to z=9.6 in the J band and z=13.3 in H band, indicating the pioneering potential of CAGIRE in identifying the most distant GRBs to date.