IceCube is a kilometer-scale high energy neutrino telescope under construction at the South Pole, a second-generation instrument expanding the capabilities of the AMANDA telescope. The scientific portfolio of IceCube includes the detection of neutrinos from astrophysical objects such as the sources of the cosmic rays, the search for dark matter, and fundamental physics using a very large data set of atmospheric neutrinos. The design and status of IceCube are briefly reviewed, followed by a summary of results to date from AMANDA and initial IceCube results from the 2007 run, with 22 of a planned 86 strings operational. The new infill array known as Deep Core, which will extend IceCube's capabilities to energies as low as 10 GeV, is also described.
IceCube is the first representative of the km^3 class of neutrino telescopes and currently the most sensitive detector to high-energy neutrinos. Its main mission is to search for Galactic and extragalactic sources of high-energy neutrinos, but it is also an excellent detector for the investigation of a variety of other highly topical astrophysics and particle physics topics like supernovae, dark matter and neutrino oscillations. After an introduction to neutrino astronomy and neutrino telescopes, this article presents a selection of latest results from the IceCube neutrino detector with respec…
This overview of neutrino astronomy emphasizes observation of astrophysical neutrinos by IceCube and interesting limits on Galactic neutrinos from IceCube and ANTARES.
Combining observational data from multiple instruments for multi-messenger astronomy can be challenging due to the complexity of the instrument response functions and likelihood calculation. We introduce a python-based unbinned-likelihood analysis package called i3mla (IceCube Maximum Likelihood Analysis). i3mla is designed to be compatible with the Multi-Mission Maximum Likelihood (3ML) framework, which enables multi-messenger astronomy analyses by combining the likelihood across different instruments. By making it possible to use IceCube data in the 3ML framework, we aim to facilitate the us…
In this paper, after a short introduction to the physics of neutrino telescopes, we will report on first performances of the IceCube detector and a selection of preliminary results obtained from data taken while IceCube operated in a partially completed configuration (22 strings and 40 strings). We will emphasize new analysis methods recently developed for the study of the Southern Hemisphere as well as for extended regions. Based on the long term experience of AMANDA and IceCube, the South Pole ice has proven to be an ideal site for astroparticle physics. New ideas and projects about the futu…
The reported association of high-energy neutrino event IceCube-170922A and blazar TXS 0506+056 has sparkled discussion about blazars as sources of cosmic neutrinos. In this paper, we use publicly released IceCube data and blazar locations from Roma-BzCat to test spacial correlation between neutrino events and blazar locations. We also scrutinize the correlation between $γ$-ray flux and neutrino flux of blazars by applying a temporal filter onto the data based on Fermi monitored source list. We find no compelling evidence to prove blazars as the main source of cosmic neutrinos, as known before …
We present a search for neutrinos in coincidence in time and direction with four fast radio bursts (FRBs) detected by the Parkes and Green Bank radio telescopes during the first year of operation of the complete IceCube Neutrino Observatory (May 2011 through May 2012). The neutrino sample consists of 138,322 muon neutrino candidate events, which are dominated by atmospheric neutrinos and muons but also contain an astrophysical neutrino component. Considering only neutrinos detected on the same day as each FRB, zero IceCube events were found to be compatible with the FRB directions within the e…
Northern hemisphere TeV gamma-ray observatories such as Milagro and Tibet AS$γ$ have demonstrated the importance of all-sky instruments by discovering previously unidentified sources that may be the PeVatrons producing cosmic rays up to the "knee" in the cosmic ray spectrum. We evaluate the potential of IceCube to identify similar sources in the southern sky by detailing an analytic approach to determine fluxes of muons from TeV gamma-ray showers. We apply this approach to known gamma-ray sources such as supernova remnants. We find that, similar to Milagro, detection is possible in 10 years fo…
Neutrino astronomy beyond the Sun was first imagined in the late 1950s; by the 1970s, it was realized that kilometer-scale neutrino detectors were required. The first such instrument, IceCube, is near completion and taking data. The IceCube project transforms a cubic kilometer of deep and ultra-transparent Antarctic ice into a particle detector. A total of 5,160 optical sensors are embedded into a gigaton of Antarctic ice to detect the Cherenkov light emitted by secondary particles produced when neutrinos interact with nuclei in the ice. Each optical sensor is a complete data acquisition syste…
With the identification of a diffuse flux of astrophysical ("cosmic") neutrinos in the TeV-PeV energy range, IceCube has opened a new window to the Universe. However, the corresponding cosmic landscape is still uncharted: so far, the observed flux does not show any clear association with known source classes. In the present talk, I sketch the way from Baikal-NT200 to IceCube and summarize IceCube's recent astrophysics results. Finally, I describe the present projects to build even larger detectors: GVD in Lake Baikal, KM3NeT in the Mediterranean Sea and IceCube-Gen2 at the South Pole. These de…
The IceCube Neutrino Observatory is the world's largest neutrino detector, instrumenting a cubic kilometer of ice at the geographic South Pole. The detector probes neutrino energies from GeV to PeV, and collects high statistics neutrino samples by virtue of its extremely large volume. IceCube was designed to detect high-energy neutrinos from potential cosmic ray acceleration sites such as active galactic nuclei, gamma ray bursts and supernova remnants. IceCube announced the detection of a diffuse flux of astrophysical neutrinos in 2013, including the highest energy neutrinos ever detected. Ice…
Motivated by the recent IceCube result, we study high energy cosmic-ray neutrino flux from the decay of a long-lived particle. Because neutrinos are so transparent, high energy neutrinos produced in the past may also contribute to the present neutrino flux. We point out that the PeV neutrino events observed by IceCube may originate in the decay of a particle much heavier than PeV if its lifetime is shorter than the present cosmic time. It is shown that the mass of the particle responsible for the IceCube event can be as large as $\sim 10^{10}\ {\rm GeV}$. We also discuss several possibilities …
IceCube is a cubic-kilometer scale neutrino detector instrumenting a gigaton of ice at the geographic South Pole in Antarctica. On average, 8 track-like high-energy neutrino events with a high probability of being astrophysical are detected and published as alerts per year. The bright appearance of these events in the detector allow a precise pointing to their origins. This work presents a search for cosmic neutrino sources. The analysis uses high statistics archival IceCube neutrino-induced through-going muon samples to search for these sources in the vicinity of the incoming directions of th…
Although IceCube has discovered a diffuse astrophysical neutrino flux, the underlying sources of these neutrinos remain unknown. Transient astrophysical objects, such as fast radio bursts (FRBs), could explain a large percentage of the measured flux. We present the analysis techniques of IceCube searches for MeV to TeV neutrinos from FRBs. As no significant correlation between IceCube neutrinos and FRBs has been found, we present the first limit on MeV neutrino emission from FRBs and the most constraining limits for neutrinos with GeV to TeV energies. We also describe the prospects for future …
The origin of the astrophysical neutrino flux reported by the IceCube Collaboration remains an open question. In this study, we use three years of publicly available IceCube data to search for evidence of neutrino emission from the blazars and non-blazar Active Galactic Nuclei (AGN) contained the Fermi 4LAC catalog. We find no evidence that these sources produce high-energy neutrinos, and conclude that blazars can produce no more than 15% of IceCube's observed flux. The constraint we derive on the contribution from non-blazar AGN, which are less luminous and more numerous than blazars, is sign…
The IceCube detector is an all-flavor neutrino telescope. For several years IceCube has been detecting muon tracks from charged-current muon neutrino interactions in ice. However, IceCube has yet to observe the electromagnetic or hadronic particle showers or "cascades" initiated by charged or neutral-current neutrino interactions. The first detection of such an event signature will likely come from the known flux of atmospheric electron and muon neutrinos. A search for atmospheric neutrino-induced cascades was performed using a full year of IceCube data. Reconstruction and background rejection…
The IceCube neutrino telescope has observed for the first time a diffuse flux of high energy neutrinos, with a possible astrophysical origin. Up to now there are no evidence of sources and many hypothesis are still plausible in order to explain the measured flux. In this proceeding we analyze an alternative way to interpret the IceCube neutrinos, in terms of sum of contributions from different sources.
The IceCube Neutrino Observatory, located at the geographic South Pole, is a Cherenkov detector that continuously monitors a cubic kilometer of instrumented glacial ice for neutrino interactions in the sub-TeV to EeV energy range. Its primary design goal is the study of powerful astrophysical objects that could act as natural particle accelerators and thus as sources of (ultra) high energy cosmic rays - in short: to do neutrino astronomy. IceCube has discovered a diffuse flux of high energy astrophysical neutrinos consistent with an extra-galactic origin. In addition the IceCube Collaboration …
Atmospheric neutrino oscillations with DeepCore; Supernova detection with IceCube and beyond; Study of South Pole ice transparency with IceCube flashers; Submitted papers to the 32nd International Cosmic Ray Conference, Beijing 2011.
We examine a framework with light new physics, which couples to the Standard Model only via neutrino mixing. Taking the hints from the short-baseline anomalies seriously and combining them with modern cosmological data and recent IceCube measurements, we obtain surprisingly effective constraints on the hidden force: keV $\lesssim M \lesssim0.3$ GeV for the mediator mass and $g_{h}>10^{-6}-10^{-3}$ for the coupling constant. Flavor equilibration between the hidden and active neutrinos can be delayed until temperatures of $\sim 1$ MeV, but not below $\sim 100$ keV. This scenario can be tested wi…
The IceCube DeepCore is a dense infill array of the IceCube Neutrino Observatory at the South Pole. While IceCube is best suited for detecting neutrinos with energies of several 100 GeV and above, DeepCore allows to probe neutrinos with lower energies. We focus on a sample of neutrinos with energies above approximately 10 GeV, which was originally optimised for oscillation experiments. Recently, it has been adapted to enable searches for transient sources of astrophysical neutrinos in the sky. In particular, this low-energy dataset can be used to conduct follow-up searches of gravitational wav…
IceCube observed high-energy neutrino flux in the energy region from TeV to PeV. The decay of a massive long-lived particle in the early universe can be the origin of the IceCube neutrino events, which we call an "early decay scenario." In this paper, we construct a particle physics model that contains such a massive long-lived particle based on the Peccei-Quinn model. We calculate the present neutrino flux, taking account of realistic initial energy distributions of particles produced by the decay of the massive long-lived particle. We show that the early decay scenario naturally fits into th…
We consider implications of the IceCube excess for hadronuclear (pp) scenarios of neutrino sources such as galaxy clusters/groups and star-forming galaxies. Since the observed neutrino flux is comparable to the diffuse gamma-ray background flux obtained by Fermi, we place new, strong upper limits on the source spectral index, Γ<2.1-2.2. In addition, the new IceCube data imply that these sources contribute at least 30%-40% of the diffuse gamma-ray background in the 100 GeV range and even ~100% for softer spectra. Our results, which are insensitive to details of the pp source models, are one of …
We analyze the high-energy neutrino events observed by IceCube, aiming to probe the initial flavor of cosmic neutrinos. We study the track-to-shower ratio of the subset with energy above 60 TeV, where the signal is expected to dominate and show that different production mechanisms give rise to different predictions even accounting for the uncertainties due to neutrino oscillations. We include for the first time the passing muons observed by IceCube in the analysis. They corroborate the hypotheses that cosmic neutrinos have been seen and their flavor matches expectations.
We present a search based on a time dependent neutrino flux prediction from the X-ray binary LS I +61 303. Results from data taken with the 22 and 40 strings of IceCube are compatible with background fluctuations.
IceCube measures the diffuse neutrino flux across several neutrino flavors and energy ranges. ESTES focuses on the measurement of the diffuse neutrino flux using high purity astrophysical muon neutrinos with energies above 1 TeV. We use the Enhanced Starting Track Event Selection dataset which selects for tracks starting within the IceCube fiducial volume. We employ a machine learning algorithm to help differentiate between tracks from atmospheric and astrophysical neutrinos. This produces a high purity diffuse neutrino sample that can provide valuable insight into the properties of the atmosp…
In 2018, the IceCube collaboration reported evidence for the identification of a blazar as an astrophysical neutrino source. That evidence is briefly summarised here before focusing on the prospects of tau neutrino physics in IceCube, both at high energies (astrophysical neutrinos) and at lower energies (atmospheric neutrino oscillations). In addition, future neutrino detectors such as KM3NeT and the IceCube Upgrade and their tau neutrino physics potential are discussed. Finally, the detection mechanism for high-energy (tau) neutrinos in the Pierre Auger Observatory and the resulting flux uppe…
IceCube, a cubic-kilometer sized neutrino detector at the Geographic South Pole, has recently discovered a diffuse all-flavor flux of astrophysical neutrinos. However, the corresponding astrophysical sources have not yet been identified in current IceCube analyses. We present a method to interpret the results of a recently published angular correlation analysis in IceCube searching for spatial clustering of muon neutrino events in terms of astrophysical models (given by an arbitrary source count distribution). We exemplarily show the resulting limits on the parameters of a class of source coun…
The association of two IceCube detections, the IceCube-170922A event and a neutrino flare, with the blazar TXS0506+056, has paved the way for the multimessenger quest for cosmic accelerators. IceCube has observed many other neutrinos but their origin remains unknown. To better understand the reason for the apparent lack of neutrino counterparts we have extended the comprehensive dissection of the sky area performed for the IceCube-170922A event to all the 70 public IceCube high-energy neutrinos that are well reconstructed and off the Galactic plane. Using the multi-frequency data available thr…
Located at the South Pole, the IceCube Neutrino Observatory is the world largest neutrino telescope, instrumenting one cubic kilometre of Antarctic ice at a depth between 1450m to 2450m. In 2013 IceCube reported the first observations of a diffuse astrophysical high-energy neutrino flux. Although the IceCube Collaboration has identified more than 100 high-energy neutrino events, the origin of this neutrino flux is still not known. Blazars, a subclass of Active Galactic Nuclei and one of the most powerful classes of objects in the Universe, have long been considered promising sources of high en…
In 2013, the IceCube Neutrino Observatory located at the geographic South Pole detected evidence for a diffuse astrophysical neutrino flux above ~60 TeV. To this day, IceCube has operated with full detector configuration for more than 6 years. The observed astrophysical neutrino flux has been confirmed with > 6$σ$ significance with both events starting within the detector (all flavor) and events traversing through the Earth ($ν_μ$ charged-current). Somewhat equal flavor ratio of astrophysical neutrinos is expected at Earth assuming standard thorough oscillation. A search for tau neutrinos has …
In this review I discuss the ultra-high energy neutrinos (UHEN) originated from Cosmic-Rays propogation (GZK neutrinos) and from Gamma Ray Bursts (GRBs), and discuss their detectability in kilometers scale detectors like ARA and IceCube. While GZK neutrinos are expected from cosmic ray interactions on the CMB, the GRB neutrinos depend on the physics inside the sources. GRBs are predicted to emit UHEN in the prompt and in the later 'after-glow' phase. I discuss the constraints on the hadronic component of GRBs derived from the search of four years of IceCube data for a prompt neutrino fux from …
Jet heating via nuclear collisions may be the main mechanism for gamma-ray burst (GRB) emission. Besides producing the observed gamma-rays, collisional heating must generate 10-100 GeV neutrinos, implying a close relation between the neutrino and gamma-ray luminosities. We exploit this theoretical relation to make predictions for possible GRB detections by IceCube+DeepCore. To estimate the expected neutrino signal, we use the largest sample of bursts observed by BATSE in 1991-2000. A GRB neutrino could have been detected if IceCube+DeepCore operated at that time. Detection of 10-100 GeV neutri…
The standard neutrino oscillation paradigm predicts almost equal fractions of astrophysical neutrino flavors at Earth regardless of their production ratio at the sources. Therefore, identification of astrophysical tau neutrinos could not only reconfirm the astrophysical neutrino flux measured by IceCube, but also is essential in precisely determining the astrophysical neutrino flavor ratio at Earth, which is an important probe for physics beyond the Standard Model over astronomical baselines. A tau neutrino undergoing a charged current (CC) interaction in IceCube could produce a double deposit…
The observed dark matter abundance in the Universe can be explained with non-thermal, heavy dark matter models. In order for dark matter to still be present today, its lifetime has to far exceed the age of the Universe. In these scenarios, dark matter decay can produce highly energetic neutrinos, along with other Standard Model particles. To date, the IceCube Neutrino Observatory is the world's largest neutrino telescope, located at the geographic South Pole. In 2013, the IceCube collaboration reported the first observation of high-energy astrophysical neutrinos. Since then, IceCube has collec…
IceCube is a km^3 scale neutrino detector being constructed deep in the Antarctic ice. When complete, IceCube will consist of 4800 optical modules deployed on 80 strings between 1450 and 2450 m of depth. During the 2007-2008 data taking season, 22 strings were operational. This configuration is already much larger than previous neutrino telescopes and provides better sensitivity to point sources of high energy (>1 TeV) neutrino emission. Such astrophysical objects are leading candidates for the acceleration of cosmic rays. We describe the IceCube detector and present the methods and results of…
IceCube has reported the detection of a diffuse TeV-PeV neutrino emission, for which the flat spectrum radio quasars (FSRQs) have been proposed to be the candidate sources. Here we assume that the neutrino flux from FSRQs is proportional to their gamma-ray ones, and obtain the gamma-ray/neutrino flux ratio by the diffuse gamma-ray flux from Fermi-LAT measurement of FSRQs and the diffuse neutrino flux detected by IceCube. We apply this ratio to individual FSRQs and hence predict their neutrino flux. We find that a large fraction of candidate FSRQs from the northern sky in the IceCube point sour…
The completed IceCube Observatory, the first km^3 neutrino telescope, is already providing the most stringent limits on the flux of high energy cosmic neutrinos from point-like and diffuse galactic and extra-galactic sources. The non-detection of extra-terrestrial neutrinos has important consequences on the origin of the cosmic rays. Here the current status of astrophysical neutrino searches, and of the observation of a persistent cosmic ray anisotropy above 100 TeV, are reviewed.
We summarize initial results for high-energy neutrino counterpart searches coinciding with gravitational-wave events in LIGO/Virgo's GWTC-2 catalog using IceCube's neutrino triggers. We did not find any statistically significant high-energy neutrino counterpart and derived upper limits on the time-integrated neutrino emission on Earth as well as the isotropic equivalent energy emitted in high-energy neutrinos for each event.
The IceCube Neutrino Observatory opened the window on neutrino astronomy by discovering high-energy astrophysical neutrinos in 2013 and identifying the first compelling astrophysical neutrino source, the blazar TXS0506+056, in 2017. In this talk, we will discuss the science reach and ongoing development of the IceCube-Gen2 facility---a planned extension to IceCube. IceCube-Gen2 will increase the rate of observed cosmic neutrinos by an order of magnitude, be able to detect five-times fainter neutrino sources, and extend the measurement of astrophysical neutrinos several orders of magnitude high…
Instrumenting a gigaton of ice at the geographic South Pole, the IceCube Neutrino Observatory has been at the forefront of groundbreaking scientific discoveries over the past decade. These include the observation of a flux of TeV-PeV astrophysical neutrinos, detection of the first astrophysical neutrino on the Glashow resonance and evidence of the blazar TXS 0506+056 as the first known astronomical source of high-energy neutrinos. Several questions, however, remain, pertaining to the precise origins of astrophysical neutrinos, their production mechanisms at the source and in Earth's atmosphere…
All sky neutrino searches: Atmospheric neutrinos; Astrophysical neutrinos; Cosmegenic neutrinos; Submitted papers to the 32nd International Cosmic Ray Conference, Beijing 2011.
The nearly isotropic distribution of the TeV-PeV neutrinos recently detected by IceCube suggests that they come from sources at distance beyond our Galaxy, but how far they are is largely unknown due to lack of any associations with known sources. In this paper, we propose that the cumulative TeV gamma-ray emission accompanying the production of neutrinos can be used to constrain the distance of these neutrino sources, since the opacity of TeV gamma rays due to absorption by the extragalactic background light (EBL) depends on the distance that these TeV gamma rays have travelled. As the diffus…
Galactic cosmic rays reach energies of at least several PeV, and their interactions should generate $γ$-rays and neutrinos from decay of secondary pions. Therefore, Galactic sources have a guaranteed contribution to the total high-energy cosmic neutrino flux observed by IceCube. Assuming that the highest energy $γ$-rays are pionic, promising neutrino source candidates have been identified based on their spectra, and observing them is likely over the lifetime of the IceCube experiment. Here, we present the search for Galactic sources of high-energy cosmic neutrinos by focusing on sources identi…
Ultrahigh-energy cosmic rays (UHECRs), if accelerated in the gamma-ray burst (GRB) blastwave, are expected to produce PeV-EeV neutrinos by interacting with long-lived GRB afterglow photons. Detailed spectral and temporal properties of the flux of these neutrinos depend on the GRB blastwave evolution scenario, but can last for days to years time scale in contrast to the seconds to minutes time scale for "burst" neutrino flux contemporaneous with the prompt gamma-ray emission and which has been constrained by IceCube in the $\sim$ 50 TeV-2 PeV range. We compute expected neutrino events in IceCub…
IceCube is a cubic kilometer neutrino detector array in the Antarctic ice that was designed to search for astrophysical, high-energy neutrinos. It has detected a diffuse flux of astrophysical neutrinos that appears to be of extragalactic origin. A possible contribution to this diffuse flux could stem from core-collapse supernovae. The high-energy neutrinos could either come from the interaction of the ejecta with a dense circumstellar medium or a jet, emanating from the star's core, that stalls in the star's envelope. Here, we will present results of a stacking analysis to search for this high…
The Telescope Array (TA) has observed a statistically significant excess in cosmic-rays with energies above 57 EeV in a region of approximately 1150 square degrees centered on coordinates (R.A. = 146.7, Dec. = 43.2). We note that the location of this excess correlates with two of the 28 extraterrestrial neutrinos recently observed by IceCube. The overlap between the two IceCube neutrinos and the TA excess is statistically significant at the 2$σ$ level. Furthermore, the spectrum and intensity of the IceCube neutrinos is consistent with a single source which would also produce the TA excess. Fin…
Powerful jets and outflows generated in tidal disruption events (TDEs) around supermassive black holes have been suggested to be possible sites producing high-energy neutrinos, but it is unclear whether such environment can provide the bulk of the neutrinos detected by the IceCube Observatory. In this work, by considering realistic limits on the non-thermal emission power of a TDE jet and the birth rate of the TDEs with jets pointing towards us, we show that it is hard to use the jetted TDE population to explain the flux and the isotropic arrival directions of the observed TeV-PeV neutrinos. T…
IceCube detects neutrinos at energies orders of magnitude higher than any neutrinos produced at particle accelerators. Neutrinos are weakly interacting particles but at energies above 30 TeV the Earth becomes opaque to neutrinos. The neutrino cross section is well predicted in the Standard Model. Any unexpected increase in the cross-section could be a sign of beyond the standard model physics. In this analysis IceCube's through-going muon neutrino flux is used to fit for the cross section of neutrino interaction, the through-going high energy neutrinos will be absorbed as they travel through t…
