136 research outputs found
Search for TeV Neutrinos from Seyfert Galaxies in the Southern Sky using Starting Track Events in IceCube
Supermassive black holes (SMBHs) power active galactic nuclei (AGN). The
vicinity of the SMBH has long been proposed as the potential site of particle
acceleration and neutrino production. Recently, IceCube reported evidence of
neutrino emission from the Seyfert II galaxy NGC 1068. The absence of a
matching flux of TeV gamma rays suggests that neutrinos are produced where
gamma rays can efficiently get attenuated, for example, in the hot coronal
environment near the SMBH at the core of the AGN. Here, we select the
intrinsically brightest (in X-ray) Seyfert galaxies in the Southern Sky from
the BAT AGN Spectroscopic Survey (BASS) and search for associated neutrinos
using starting track events in IceCube. In addition to the standard power law
flux assumption, we leverage a dedicated disc-corona model of neutrino
production in such an environment to improve the discovery potential of the
search. In this contribution, we report on the expected performance of our
searches for neutrinos from these Seyfert galaxies.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023).
See arXiv:2307.13047 for all IceCube contribution
New Constraints on Supersymmetry Using Neutrino Telescopes
We demonstrate that megaton-mass neutrino telescopes are able to observe the
signal from long-lived particles beyond the Standard Model, in particular the
stau, the supersymmetric partner of the tau lepton. Its signature is an excess
of charged particle tracks with horizontal arrival directions and energy
deposits between 0.1 and 1 TeV inside the detector. We exploit this
previously-overlooked signature to search for stau particles in the publicly
available IceCube data. The data shows no evidence of physics beyond the
Standard Model. We derive a new lower limit on the stau mass of GeV (95\%
C.L.) and estimate that this new approach, when applied to the full data set
available to the IceCube collaboration, will reach world-leading sensitivity to
the stau mass ()
All-sky search for time-integrated neutrino emission from astrophysical sources with 7 years of IceCube data
Since the recent detection of an astrophysical flux of high energy neutrinos,
the question of its origin has not yet fully been answered. Much of what is
known about this flux comes from a small event sample of high neutrino purity,
good energy resolution, but large angular uncertainties. In searches for
point-like sources, on the other hand, the best performance is given by using
large statistics and good angular reconstructions. Track-like muon events
produced in neutrino interactions satisfy these requirements. We present here
the results of searches for point-like sources with neutrinos using data
acquired by the IceCube detector over seven years from 2008--2015. The
discovery potential of the analysis in the northern sky is now significantly
below , on average
lower than the sensitivity of the previously published analysis of four
years exposure. No significant clustering of neutrinos above background
expectation was observed, and implications for prominent neutrino source
candidates are discussed.Comment: 19 pages, 17 figures, 3 tables; ; submitted to The Astrophysical
Journa
The contribution of Fermi-2LAC blazars to the diffuse TeV-PeV neutrino flux
The recent discovery of a diffuse cosmic neutrino flux extending up to PeV
energies raises the question of which astrophysical sources generate this
signal. One class of extragalactic sources which may produce such high-energy
neutrinos are blazars. We present a likelihood analysis searching for
cumulative neutrino emission from blazars in the 2nd Fermi-LAT AGN catalogue
(2LAC) using an IceCube neutrino dataset 2009-12 which was optimised for the
detection of individual sources. In contrast to previous searches with IceCube,
the populations investigated contain up to hundreds of sources, the largest one
being the entire blazar sample in the 2LAC catalogue. No significant excess is
observed and upper limits for the cumulative flux from these populations are
obtained. These constrain the maximum contribution of the 2LAC blazars to the
observed astrophysical neutrino flux to be or less between around 10
TeV and 2 PeV, assuming equipartition of flavours at Earth and a single
power-law spectrum with a spectral index of . We can still exclude that
the 2LAC blazars (and sub-populations) emit more than of the observed
neutrinos up to a spectral index as hard as in the same energy range.
Our result takes into account that the neutrino source count distribution is
unknown, and it does not assume strict proportionality of the neutrino flux to
the measured 2LAC -ray signal for each source. Additionally, we
constrain recent models for neutrino emission by blazars.Comment: 18 pages, 22 figure
Non-standard neutrino interactions in IceCube
Non-standard neutrino interactions (NSI) may arise in various types of new physics. Their existence would change the potential that atmospheric neutrinos encounter when traversing Earth matter and hence alter their oscillation behavior. This imprint on coherent neutrino forward scattering can be probed using high-statistics neutrino experiments such as IceCube and its low-energy extension, DeepCore. Both provide extensive data samples that include all neutrino flavors, with oscillation baselines between tens of kilometers and the diameter of the Earth.
DeepCore event energies reach from a few GeV up to the order of 100 GeV - which marks the lower threshold for higher energy IceCube atmospheric samples, ranging up to 10 TeV.
In DeepCore data, the large sample size and energy range allow us to consider not only flavor-violating and flavor-nonuniversal NSI in the μ−τ sector, but also those involving electron flavor.
The effective parameterization used in our analyses is independent of the underlying model and the new physics mass scale. In this way, competitive limits on several NSI parameters have been set in the past. The 8 years of data available now result in significantly improved sensitivities. This improvement stems not only from the increase in statistics but also from substantial improvement in the treatment of systematic uncertainties, background rejection and event reconstruction
IceCube Search for Earth-traversing ultra-high energy Neutrinos
The search for ultra-high energy neutrinos is more than half a century old. While the hunt for these neutrinos has led to major leaps in neutrino physics, including the detection of astrophysical neutrinos, neutrinos at the EeV energy scale remain undetected. Proposed strategies for the future have mostly been focused on direct detection of the first neutrino interaction, or the decay shower of the resulting charged particle. Here we present an analysis that uses, for the first time, an indirect detection strategy for EeV neutrinos. We focus on tau neutrinos that have traversed Earth, and show that they reach the IceCube detector, unabsorbed, at energies greater than 100 TeV for most trajectories. This opens up the search for ultra-high energy neutrinos to the entire sky. We use ten years of IceCube data to perform an analysis that looks for secondary neutrinos in the northern sky, and highlight the promise such a strategy can have in the next generation of experiments when combined with direct detection techniques
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