IceCube's discovery of the astrophysical neutrino flux in the TeV-PeV range marked a crucial milestone in the development of high-energy neutrino astronomy. Recent searches identified the blazar TXS 0506+056 and the Seyfert Galaxy NGC 1068 as the first candidates for extragalactic neutrino emitters, standing out above the largely isotropic neutrino flux. While both objects are classified as...
IceCube has discovered a flux of astrophysical neutrinos and presented evidence for the first neutrino sources, a flaring blazar known as TXS 0506+056 and the active galaxy NGC 1068. However, the sources responsible for the majority of the astrophysical neutrino flux remain elusive. High-energy neutrinos can be produced when cosmic rays interact at their acceleration sites and during...
The accretion flows around supermassive black holes would be a part of emission sources of the IceCube neutrinos. The effects of the global structure of the magnetized accretion flows on the neutrino SEDs are, however, still uncertain. We, therefore, carry out the calculation of SEDs of high energy neutrinos by using three dimensional general relativistic magnetohydrodynamic (GRMHD)...
Over the past decade, a significant number of supernovae exhibiting luminosities that exceed $10^{43}\,\mathrm{erg\, s^{-1}}$ and characterized by narrow hydrogen lines in their spectra have been discovered. These supernovae are believed to be powered by the collision of ejected material with a dense circumstellar medium (CSM). The interaction of the SNe ejecta with the CSM results in a shock...
The ultra-high energy cosmic neutrinos, which usually perambulate gargantuan scales in the extragalactic universe, are expected to play a crucial role in determining the origin of cosmic rays as well as probing new physics extending even up to the Planck scale. This epitomizes the selling point of several currently running or planned neutrino telescopes. If neutrinos have magnetic moment owing...
Absorption and emission lines in the optical spectrum are typically used to investigate the presence of large-scale environments in active galactic nuclei (AGNs). BL Lac objects - which are a category of AGNs with the relativistic jet pointing directly to the observer - are supposed to represent a late evolution stage of AGNs. Their large-scale structures are probably poorer of material, which...
Resolving the origin of diffuse TeV-PeV neutrino emission measured by the IceCube Observatory is a key part of multi-messenger astronomy. We study the neutrino emission of Galactic and extragalactic source populations by investigating the relation between IceCube's point-source discovery potential and diffuse flux observations. For Galactic sources, we show that the flux of unresolved neutrino...
It is well known that our Universe is opaque to high-energy gamma-rays due to electromagnetic cascades over cosmological distances, resulting in a spectrum of secondary gamma-rays at lower energies. In this talk, we will summarize the physics and features of such cascades and discuss their importance in the context of multimessenger astrophysics up to ultra-high energies. In particular, we...
The Pacific Ocean Neutrino Experiment is a new neutrino telescope in the Pacific Ocean that is planned to consist of at least 70 instrumented mooring lines and span more than one cubic kilometre. Using the existing underwater infrastructure of Ocean Networks Canada, P-ONE aims to detect neutrinos with energies ranging from TeV to PeV, and will complement the sky coverage of both IceCube and...
The STRings for Absorption length in Water (STRAW) and its successor STRAW-b are the pathfinders for the future Pacific Ocean Neutrino Experiment (P-ONE). Both experiments are mooring lines instrumented with several light emitter and receiver modules. The goals of the pathfinders are to measure the water's attenuation length of water, characterize the background light spectrum and perform...
On behalf of the KM3NeT Collaboration.
Strong star-forming activity in astrophysical environments leads to an enhancement of hadronic gamma-ray and neutrino emissions. In this contribution, we explore the capability of the full KM3NeT/ARCA detector to trace TeVs neutrinos from star-forming environments, encompassing both diffuse and point-like signals. For the diffuse analysis,
we compute...
The detection of MeV-GeV neutrinos from astronomical sources is a long-lasting challenge for neutrino experiments. The low flux predicted for transient sources, such as solar flares, would require a detector with both a large instrumented volume as well as a high density of photomultipliers (PMTs) to resolve the low-energy signature. We discuss how KM3NeT can play a key role in the search for...
The detection of high-energy astrophysical neutrinos by IceCube has opened a new window on our Universe. While IceCube has measured the flux of these neutrinos at energies up to several PeV, much remains to be discovered regarding their origin and nature. Currently, measurements are limited by the small sample size of astrophysical neutrinos and by the difficulty of discriminating between...
IceCube has reported evidence for neutrino emission from the nearby active galaxy NGC 1068 and the gamma-ray blazar TXS 0506+056. A search for electromagnetic radiation temporally and spatially-correlated with high-energy IceCube neutrino events is an important strategy for exploring the connection between neutrinos and high-energy blazars. Here we report on the very-high-energy gamma-ray and...
The search for gamma ray counterparts of IceCube neutrino events is crucial for understanding the role of blazars as possible sources of cosmic neutrinos. We have searched the counterparts for IceCube neutrinos events in the AGILE gamma-ray satellite public archive in the interval 2018-2020.
We present the candidate sources in the regions centered on the detected neutrinos and their light...
A remarkable detection was recently made when a high-energy neutrino event detected by IceCube was linked to the Fermi-LAT detected blazar TXS 0506+056. However, our knowledge of observable neutrino-emitting blazars is limited, hindering future investigations. To address this issue, we combine a physically motivated model with three key free parameters capable of producing both...
In the last decade, the IceCube South Pole Neutrino Observatory has observed an astrophysical neutrino flux with unexpected implications for the environments of extragalactic accelerators. The discovery of the high-energy, transient neutrino source TXS 0506+056 has drawn further attention to blazars, and the traditional correlation of their activity with gamma-ray emission. However, gamma-ray...
Recent observations are shedding light on the important role that active galactic nuclei (AGNs) play in the production of high-energy neutrinos. Despite the growing evidence that blazars are good candidates to be neutrino emitters, our understanding of the physical processes and locations of production remains limited.
In this contribution we present the study of one promising object, 5BZB...
The IceCube telescope found an excess of 79 neutrinos
at Tera-electron-volt energies correlated with the galaxy NCG1068 (the corresponding significance is 4.2 sigmas), making this Seyfert galaxy spatially coincident with the
hottest spot in the northern high-energy neutrino sky.
Considering that NGC1068 presents a core with a high star-formation rate and hosts an active galactic nucleus,...
According to the observations up to date, there is more flux in cosmic neutrinos at lower energies (<100 TeV) than that could be expected from gamma rays, if they have the same sources. The diffuse gamma-ray sky observed by the Fermi Gamma-ray Space Telescope is dominated by blazars (~80%), while recent studies suggest blazars might be only subdominant sources of the diffuse high-energy...
In this talk, I will analyse the effect on the supernova neutrino flux duration of the resonant production of low-mass vector mediators from neutrino-antineutrino coalescence in the core of proto-neutron stars. First, I will argue that, in the regime where neutrino-antineutrino interactions via the new vector mediator dominate over the Standard Model neutrino-nucleon scattering, a...
Ever since the discovery of neutrinos, we have wondered if neutrinos are their own antiparticles, and whether lepton number is violated or not. One remarkable possibility is that lepton-number violation in the Standard Model is soft. In such scenarios, neutrinos have a pseudo-Dirac nature, with a tiny mass difference between active and sterile states, having oscillations driven by this tiny...
Neutrino flavor oscillation is a widely studied physical phenomena with far reaching consequences in understanding the standard model of particle physics and to search for physics beyond it. Oscillation arises because of mixing of the mass states in flavor states, and their evolution over time. It is an inherent quantum system for which flavor transitions are traditionally studied with...
The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for $0\nu\beta\beta$ decay that has successfully reached the one-tonne mass scale. The detector, located at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, consists of an array of 988 TeO$_2$ crystals arranged in a compact cylindrical structure of 19 towers. CUORE began its first...
Elucidating the Majorana-Dirac nature of the neutrino remains a long-standing question, a discovery of which would provide unique and powerful insight into the building blocks of our Universe. The LEGEND (Large Enriched Germanium Experiment for Neutrinoless double beta Decay) experiment is designed to answer this very question. Using a large array of high-purity germanium (HPGe) detectors...
The observation of coherent elastic neutrino nucleus scattering (CEvNS) has opened the window to many physics opportunities. In this talk I will discuss the implication of the observation of CEvNS by the COHERENT Collaboration using two different targets, CsI and argon, on new physics scenarios. These include, for instance, new light mediators and the possible production of a dark fermion.
Over the past decade, the IceCube detector has gone from the discovery of an astrophysical neutrino flux at earth to the identification of two neutrino sources, TXS 0506+056 and NGC 1068. However, efforts continue within IceCube to pull more astrophysical neutrino events out of the data. Here, we present the results from a new IceCube event sample which selects for starting track events...
IceCube, a cubic-kilometer Cherenkov Neutrino detector located at the South Pole has been able to put constraints on the diffuse astrophysical neutrino flavour ratio measured on Earth by establishing the existence of the astrophysical tau neutrino component of the neutrino flux. This measurement was made using the High Energy Starting Event (HESE) sample collected for over 7.5 years containing...
Starting track events in the IceCube Neutrino Observatory, a gigaton ice-Cherenkov detector at the South Pole, arise from muon neutrino and antineutrino charged-current interactions in the detector. By reconstructing the energies of the hadronic shower and secondary muon separately, one can obtain the inelasticity of the event. This observable enables various measurements, including the ratio...
The IceCube collaboration has recently found evidence for connecting the blazar TXS 0506+056 to high-energy neutrino events. Observations of spatial correlations between neutrino hotspots and locations of blazars have also hinted at a blazar-neutrino connection (Buson et al. 2022, 2023). Several other studies have independently investigated the hypothesis of blazars as neutrino emitters with...
AGN are powerful sources that are believed to be capable of accelerating particles to high energies. In environments with gas or photon targets, cosmic-ray interactions transpire leading to the production of pionic gamma rays and neutrinos. Since the AGN environment is rich in gas, dust and photons, they are promising candidate sources of high-energy astrophysical neutrinos. While the...
The IceCube Neutrino Observatory measures astrophysical and atmospheric neutrinos from the entire sky. The detector array measures Cherenkov light emitted when neutrinos interact in the ice and produce charged leptons. The presence of astrophysical neutrinos has been established by the High Energy Starting Events (HESE) selection. HESE measures these astrophysical neutrinos at energies above...
Galaxy Clusters are considered to be efficient containers of cosmic rays (CRs). In their formation history, CRs are accelerated by active galactic nuclei, and cosmological shocks and turbulence, and they are accumulated in the intra-cluster space. The magnetic field and cosmic ray electrons in massive clusters have been proved with the observations diffuse radio emission. However, the content...
Earth neutrino tomography is a realistic possibility with current and future neutrino detectors, complementary to geophysics methods. The two main approaches are based on either partial absorption of the neutrino flux as it propagates through the Earth (at energies about a few TeV) or on coherent Earth matter effects affecting the neutrino oscillations pattern (at energies below a few tens of...
