Search for transient sources with the ANTARES and KM3NeT neutrino telescopes in the multi-messenger astronomy era

En el presente manuscrito se expone el trabajo realizado en el seno de la Collaboración ANTARES-KM3NeT sobre la astronomía multi-mensanjero con neutrinos, que se ha enfocado en dos ejes: la detección de neutrinos de supernova a bajas energías (MeV) con los telecopios KM3NeT y la búsqueda de neutrinos de alta energía (TeV-PeV) en ANTARES en coincidencia con fuentes transitorias detectadas en ondas gravitationales o rayos gamma de muy alta energía O(TeV). El primer análisis, explora la capacidad de los telescopios de neutrinos KM3NeT para detectar la señal de una explosión de supernova (CCSN), así como el potencial de explotar dicha detección para aprender sobre la física que hay detrás, en particular la resolución del perfil temporal y el espectro en energía de esta señal. Junto con el Sol, las explosiones de supernova son la única fuente astrofísica de neutrinos que ha sido observada. Durante la tesis se ha desarrollado un método de búsqueda para detectar estos neutrinos astrofísicos de baja energía, que se basa en el análisis de los primeros datos de KM3NeT para caracterizar el ruido de fondo y la respuesta del detector. Los resultados de dicho análisis muestran que los detectores KM3NeT son sensibles a un flujo de neutrinos con energías del MeV, y serán capaces de detectar fuentes supernova en nuestra Galaxia con una probabilidad a 5 sigmas, y por tanto contribuirán a la observación de la próxima explosión Galáctica. Este análisis se ha implementado para búsquedas a tiempo real de forma que nos permita mandar alertas en caso en una detección probable, y está en funcionamiento constante desde 2019. De hecho, este análisis se ha aplicado al seguimiento de las alertas de eventos detectados por ondas gravitacionales como fuentes no modelizadas, que son posibles candidatos a ser supernova, lo que ha llevado a los primeros resultados multi-mensajero de KM3NeT. Además, los resultados de este análisis ha permitido que KM3NeT entre a formar parte de la colaboración SNEWS, que reúne a todos los detectores sensibles a la señal de neutrinos de supernova y recibe sus alertas. El segundo análisis, utiliza los datos del detector ANTARES para buscar neutrinos de alta energía (TeV-PeV) en coincidencia espacial y temporal con la detección de fuentes astrofísicas mediante otros mensajeros. En particular, con señales detectados por ondas gravitacionales (GWs) y con las primeras detecciones de “bursts” de rayos gamma (GRBs) a muy alta energía O(TeV) por telescopios de tipo Cherenkov (IATC’s). De hecho, las colisiones de objetos compactos en sistemas binarios (fuentes de ondas gravitacionales) y las fuentes de rayos gamma energéticos, han sido sugeridos durante mucho tiempo como posibles emisores de neutrinos cósmicos. De normal, las búsquedas de fuentes de neutrinos se centran en neutrinos muónicos que atraviesan la tierra antes de ser detectados en el detector (trazas ascendentes), lo que permite de deshacerse del ruido de fondo de los muones atmosféricos. Por primera vez, todos los sabores de neutrinos (incluyendo los llamados eventos de tipo cascada) han sido considerados en esto tipo de análisis. Además, la búsqueda realizada en el este trabajo, es aplicable a fuentes tanto por encima como por debajo del horizonte de ANTARES (eventos ascendentes y descendentes), lo que permite una cobertura de todo el cielo. Esto es posible gracias a las reducidas ventanas espacial y temporal utilizadas. Los análisis multi-mensajero con ANTARES llevados a cabo durante la tesis han dado resultado que no se han encontrado neutrinos en coincidencia con ninguno de los señales GWs ni GRBs considerados en las búsquedas. Sin embargo, los resultados de este análisis muestran una mejora de la sensibilidad de un 15-30% para fuentes en el horizonte de ANTARES, y hasta un 200% cuando la búsqueda utiliza eventos descendentes, y han llevado a los mejores límites de emisión de neutrinos publicados por ANTARES para este tipo de fuentes.Two analyses are detailed in this thesis related to neutrino and multi-messenger astronomy with Cherenkov telescopes in the Mediterranean Sea. The first analysis explores the capabilities of the KM3NeT neutrino telescopes to detect the signal from a Galactic core-collapse supernova (CCSN), as well as the physical constraints that could be extracted from such a detection. Together with the Sun, CCSNe are the only confirmed sources of astrophysical neutrinos. A search method for these astrophysical neutrino sources with KM3NeT has been developed during this thesis, based on the analysis of the first data which has allowed for a good characterisation of the background and the detector performance. The results show that the KM3NeT detector might be sensitive to this MeV neutrino flux, with a coverage at 5 sigma discovery potential of more than 95% of Galactic CCSN progenitors. Therefore, KM3NeT will contribute to the observation of the next Galactic explosion. The CCSN analysis has been implemented in a real-time trigger, that is active since summer 2019. Moreover, it has yielded the first KM3NeT real-time results with the follow-up of the unmodelled candidate gravitational-wave (GW) events. These results have allowed the KM3NeT experiment to join the SNEWS network, to which all detectors sensitive to CCSN neutrino send their alerts. The second analysis exploits the data of the ANTARES neutrino telescope to search for high-energy neutrinos (TeV-PeV) in time and space coincidence with gravitational-wave sources and very-high energy gamma-ray bursts (GRBs). In fact, compact binary mergers and gamma-ray bursts have long been suggested as potential high-energy neutrino emitters. Typically, these searches look for muon neutrinos coming through the Earth (upgoing tracks). For the first time, all-flavors (including the so-called shower events) were included in this kind of searches. Moreover, these analyses have been applied to sources both below the ANTARES horizon (seen as upgoing events), and above the horizon of the ANTARES telescope (downgoing). This has lead to an improvement of 15-30% for upgoing events and up to a 200% for searches above the horizon. The analyses carried out during the thesis yielded no neutrino in coincidence with any of the gravitational-wave sources from the first GW catalog, neither with the first GRBs detected at very high energies

Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova

We compile a catalog of 598 highly probable and 79 likely red supergiants (RSGs) of the Milky Way, which represents the largest list of Galactic RSG candidates to date. We matched distances measured by Gaia DR3, 2MASS photometry, and a 3D Galactic dust map to obtain luminous bright late-type stars. Determining the stars' bolometric luminosities and effective temperatures, we compared to Geneva stellar evolution tracks to determine likely RSG candidates, and quantified contamination using a catalog of Galactic AGB in the same luminosity-temperature space. We add details for common or interesting characteristics of RSG, such as multi-star system membership, variability, and classification as a runaway. As potential future core-collapse supernova (SN) progenitors, we studied the ability of the catalog to inform the Supernova Early Warning System (SNEWS) coincidence network made to automate pointing, and show that for 3D position estimates made possible by neutrinos, the number of progenitor candidates can be significantly reduced, improving our ability to observe the progenitor pre-explosion and the early phases of the core-collapse supernova.Comment: 21 pages, 10 figures, 5 table. Comments welcom

Red supergiant candidates for multimessenger monitoring of the next Galactic supernova

We compile a catalogue of 578 highly probable and 62 likely red supergiants (RSGs) of the Milky Way, which represents the largest list of Galactic RSG candidates designed for continuous follow-up efforts to date. We match distances measured by Gaia DR3, 2MASS photometry, and a 3D Galactic dust map to obtain luminous bright late-type stars. Determining the stars' bolometric luminosities and effective temperatures, we compare to Geneva stellar evolution tracks to determine likely RSG candidates, and quantify contamination using a catalogue of Galactic AGB in the same luminosity-temperature space. We add details for common or interesting characteristics of RSG, such as multistar system membership, variability, and classification as a runaway. As potential future core-collapse supernova progenitors, we study the ability of the catalogue to inform the Supernova Early Warning System (SNEWS) coincidence network made to automate pointing, and show that for 3D position estimates made possible by neutrinos, the number of progenitor candidates can be significantly reduced, improving our ability to observe the progenitor pre-explosion and the early phases of core-collapse supernovae

Implementation and performances of the IPbus protocol for the JUNO Large-PMT readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino detector currently under construction in China. Thanks to the tight requirements on its optical and radio-purity properties, it will be able to perform leading measurements detecting terrestrial and astrophysical neutrinos in a wide energy range from tens of keV to hundreds of MeV. A key requirement for the success of the experiment is an unprecedented 3% energy resolution, guaranteed by its large active mass (20 kton) and the use of more than 20,000 20-inch photo-multiplier tubes (PMTs) acquired by high-speed, high-resolution sampling electronics located very close to the PMTs. As the Front-End and Read-Out electronics is expected to continuously run underwater for 30 years, a reliable readout acquisition system capable of handling the timestamped data stream coming from the Large-PMTs and permitting to simultaneously monitor and operate remotely the inaccessible electronics had to be developed. In this contribution, the firmware and hardware implementation of the IPbus based readout protocol will be presented, together with the performances measured on final modules during the mass production of the electronics

Mass testing of the JUNO experiment 20-inch PMTs readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose, large size, liquid scintillator experiment under construction in China. JUNO will perform leading measurements detecting neutrinos from different sources (reactor, terrestrial and astrophysical neutrinos) covering a wide energy range (from 200 keV to several GeV). This paper focuses on the design and development of a test protocol for the 20-inch PMT underwater readout electronics, performed in parallel to the mass production line. In a time period of about ten months, a total number of 6950 electronic boards were tested with an acceptance yield of 99.1%

Event reconstruction for KM3NeT/ORCA using convolutional neural networks

The KM3NeT research infrastructure is currently under construction at two locations in the Mediterranean Sea. The KM3NeT/ORCA water-Cherenkov neutrino detector off the French coast will instrument several megatons of seawater with photosensors. Its main objective is the determination of the neutrino mass ordering. This work aims at demonstrating the general applicability of deep convolutional neural networks to neutrino telescopes, using simulated datasets for the KM3NeT/ORCA detector as an example. To this end, the networks are employed to achieve reconstruction and classification tasks that constitute an alternative to the analysis pipeline presented for KM3NeT/ORCA in the KM3NeT Letter of Intent. They are used to infer event reconstruction estimates for the energy, the direction, and the interaction point of incident neutrinos. The spatial distribution of Cherenkov light generated by charged particles induced in neutrino interactions is classified as shower- or track-like, and the main background processes associated with the detection of atmospheric neutrinos are recognized. Performance comparisons to machine-learning classification and maximum-likelihood reconstruction algorithms previously developed for KM3NeT/ORCA are provided. It is shown that this application of deep convolutional neural networks to simulated datasets for a large-volume neutrino telescope yields competitive reconstruction results and performance improvements with respect to classical approaches

Event reconstruction for KM3NeT/ORCA using convolutional neural networks

The KM3NeT research infrastructure is currently under construction at two locations in the Mediterranean Sea. The KM3NeT/ORCA water-Cherenkov neutrino de tector off the French coast will instrument several megatons of seawater with photosensors. Its main objective is the determination of the neutrino mass ordering. This work aims at demonstrating the general applicability of deep convolutional neural networks to neutrino telescopes, using simulated datasets for the KM3NeT/ORCA detector as an example. To this end, the networks are employed to achieve reconstruction and classification tasks that constitute an alternative to the analysis pipeline presented for KM3NeT/ORCA in the KM3NeT Letter of Intent. They are used to infer event reconstruction estimates for the energy, the direction, and the interaction point of incident neutrinos. The spatial distribution of Cherenkov light generated by charged particles induced in neutrino interactions is classified as shower-or track-like, and the main background processes associated with the detection of atmospheric neutrinos are recognized. Performance comparisons to machine-learning classification and maximum-likelihood reconstruction algorithms previously developed for KM3NeT/ORCA are provided. It is shown that this application of deep convolutional neural networks to simulated datasets for a large-volume neutrino telescope yields competitive reconstruction results and performance improvements with respect to classical approaches

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Multi-messenger searches with the ANTARES and KM3NeT neutrino telescopes

International audienceThe year 2017 brought important breakthroughs to the astro-particle community, the firstdetection of an electromagnetic counterpart of the gravitational wave signal from a binaryneutron star merger and the potential correlation between high-energy neutrinos observed by theIceCube telescope and the flaring blazar TXS 0506+056. These observations have opened a newway to probe extreme phenomena in the sky. Combination of these messengers is now possibleand fundamental information can be obtained with these new probes.The ANTARES neutrino telescope has been operating for more than ten years in the Mediter-ranean sea with the purpose of searching for high energy cosmic neutrinos. During the last fewyears the multi-messenger approach has delivered intriguing new results for Cherenkov neutrinodetectors with promising potential for future astrophysical searches. Thus, the ANTARES Col-laboration is actively participating to the follow up of alerts sent by different experiments cover-ing the full electromagnetic spectrum, IceCube and the gravitational-wave interferometers. Thisallows probe the potential neutrino emission from various sources, including fast radio bursts,gamma-ray bursts, binary mergers and blazars. ANTARES also sends alerts that lead to an elec-tromagnetic follow-up of interesting neutrino events. The latest results will be discussed in thefollowing

JUNO Detector Design and Status

The Jiangmen Underground Neutrino Observatory (JUNO) is a next generation multipurpose liquid scintillator detector being built in China. It will address a wide range of topics in neutrino physics: the determination of the neutrino mass ordering and the sub-percent measurement of three oscillation parameters from reactor neutrino oscillations, detection of solar, atmospheric and supernova neutrinos as well as the search for physics beyond the Standard Model. The JUNO detector design is optimised towards the determination of the neutrino mass ordering by reaching an unprecedented energy resolution and a low background. The experimental hall, which was recently successfully dug out, is located under about 700~m of granite overburden. The center of the instrument consists of a 35.4-meter diameter acrylic vessel containing 20 kt of LAB-based liquid scintillator, making it the largest liquid scintillator detector in the world. The spherical detector is submerged in a water pool shielding doubling as a water Cherenkov detector which, along with a top tracker above it, serves to precisely reconstruct and veto atmospheric muons. Surrounding the vessel are 17612 20” photomultiplier tubes (PMTs) and 25600 3” PMTs, which will collect the light induced by neutrinos interacting in the detector. This document presents the detector design and construction status of JUNO, which is expected to start taking data in 2023on behalf of the JUNO collaborationinfo:eu-repo/semantics/publishe