Abstract
Galactic PeV cosmic-ray accelerators (PeVatrons) are Galactic sources theorized to accelerate cosmic rays up to PeV in energy. The accelerated cosmic rays are expected to interact ...hadronically with nearby ambient gas or the interstellar medium, resulting in
γ
-rays and neutrinos. Recently, the Large High Altitude Air Shower Observatory (LHAASO) identified 12
γ
-ray sources with emissions above 100 TeV, making them candidates for PeVatrons. While at these high energies the Klein–Nishina effect exponentially suppresses leptonic emission from Galactic sources, evidence for neutrino emission would unequivocally confirm hadronic acceleration. Here, we present the results of a search for neutrinos from these
γ
-ray sources and stacking searches testing for excess neutrino emission from all 12 sources as well as their subcatalogs of supernova remnants and pulsar wind nebulae with 11 yr of track events from the IceCube Neutrino Observatory. No significant emissions were found. Based on the resulting limits, we place constraints on the fraction of
γ
-ray flux originating from the hadronic processes in the Crab Nebula and LHAASO J2226+6057.
Abstract
The IceCube Neutrino Observatory has been continuously taking data to search for
O
(
0.5
–
10
)
s long neutrino bursts since 2007. Even if a Galactic core-collapse supernova is optically ...obscured or collapses to a black hole instead of exploding, it will be detectable via the
O
(
10
)
MeV neutrino burst emitted during the collapse. We discuss a search for such events covering the time between 2008 April 17 and 2019 December 31. Considering the average data taking and analysis uptime of 91.7% after all selection cuts, this is equivalent to 10.735 yr of continuous data taking. In order to test the most conservative neutrino production scenario, the selection cuts were optimized for a model based on an 8.8 solar mass progenitor collapsing to an O–Ne–Mg core. Conservative assumptions on the effects of neutrino oscillations in the exploding star were made. The final selection cut was set to ensure that the probability to detect such a supernova within the Milky Way exceeds 99%. No such neutrino burst was found in the data after performing a blind analysis. Hence, a 90% C.L. upper limit on the rate of core-collapse supernovae out to distances of ≈25 kpc was determined to be 0.23 yr
−1
. For the more distant Magellanic Clouds, only high neutrino luminosity supernovae will be detectable by IceCube, unless external information on the burst time is available. We determined a model-independent limit by parameterizing the dependence on the neutrino luminosity and the energy spectrum.
Abstract
This paper presents the results of a search for neutrinos that are spatially and temporally coincident with 22 unique, nonrepeating fast radio bursts (FRBs) and one repeating FRB (FRB ...121102). FRBs are a rapidly growing class of Galactic and extragalactic astrophysical objects that are considered a potential source of high-energy neutrinos. The IceCube Neutrino Observatory’s previous FRB analyses have solely used track events. This search utilizes seven years of IceCube cascade events which are statistically independent of track events. This event selection allows probing of a longer range of extended timescales due to the low background rate. No statistically significant clustering of neutrinos was observed. Upper limits are set on the time-integrated neutrino flux emitted by FRBs for a range of extended time windows.
Abstract Neutrino flares in the sky are searched for in data collected by IceCube between 2011 and 2021 May. This data set contains cascade-like events originating from charged-current electron ...neutrino and tau neutrino interactions and all-flavor neutral-current interactions. IceCube’s previous all-sky searches for neutrino flares used data sets consisting of track-like events originating from charged-current muon neutrino interactions. The cascade data set is statistically independent of the track data sets, and while inferior in angular resolution, the low-background nature makes it competitive and complementary to previous searches. No statistically significant flare of neutrino emission was observed in an all-sky scan. Upper limits are calculated on neutrino flares of varying duration from 1 hr to 100 days. Furthermore, constraints on the contribution of these flares to the diffuse astrophysical neutrino flux are presented, showing that multiple unresolved transient sources may contribute to the diffuse astrophysical neutrino flux.
Particle dark matter could belong to a multiplet that includes an electrically charged state. WIMP dark matter (\(\chi^{0}\)) accompanied by a negatively charged excited state (\(\chi^{-}\)) with a ...small mass difference (e.g. \(<\) 20 MeV) can form a bound-state with a nucleus such as xenon. This bound-state formation is rare and the released energy is \(\mathcal{O}(1-10\)) MeV depending on the nucleus, making large liquid scintillator detectors suitable for detection. We searched for bound-state formation events with xenon in two experimental phases of the KamLAND-Zen experiment, a xenon-doped liquid scintillator detector. No statistically significant events were observed. For a benchmark parameter set of WIMP mass \(m_{\chi^{0}} = 1\) TeV and mass difference \(\Delta m = 17\) MeV, we set the most stringent upper limits on the recombination cross section times velocity \(\langle\sigma v\rangle\) and the decay-width of \(\chi^{-}\) to \(9.2 \times 10^{-30}\) \({\rm cm^3/s}\) and \(8.7 \times 10^{-14}\) GeV, respectively at 90% confidence level.
We present a search for neutrinoless double-beta (\(0\nu\beta\beta\)) decay of \(^{136}\)Xe using the full KamLAND-Zen 800 dataset with 745 kg of enriched xenon, corresponding to an exposure of ...\(2.097\) ton yr of \(^{136}\)Xe. This updated search benefits from a more than twofold increase in exposure, recovery of photo-sensor gain, and reduced background from muon-induced spallation of xenon. Combining with the search in the previous KamLAND-Zen phase, we obtain a lower limit for the \(0\nu\beta\beta\) decay half-life of \(T_{1/2}^{0\nu} > 3.8 \times 10^{26}\) yr at 90% C.L., a factor of 1.7 improvement over the previous limit. The corresponding upper limits on the effective Majorana neutrino mass are in the range 28-122 meV using phenomenological nuclear matrix element calculations.
We report a measurement of the strange axial coupling constant \(g_A^s\) using atmospheric neutrino data at KamLAND. This constant is a component of the axial form factor of the neutral-current ...quasielastic (NCQE) interaction. The value of \(g_A^s\) significantly changes the ratio of proton and neutron NCQE cross sections. KamLAND is suitable for measuring NCQE interactions as it can detect nucleon recoils with low-energy thresholds and measure neutron multiplicity with high efficiency. KamLAND data, including the information on neutron multiplicity associated with the NCQE interactions, makes it possible to measure \(g_A^s\) with a suppressed dependence on the axial mass \(M_A\), which has not yet been determined. For a comprehensive prediction of the neutron emission associated with neutrino interactions, we establish a simulation of particle emission via nuclear deexcitation of \(^{12}\)C, a process not considered in existing neutrino Monte Carlo event generators. Energy spectrum fitting for each neutron multiplicity gives \(g_A^s =-0.14^{+0.25}_{-0.26}\), which is the most stringent limit obtained using NCQE interactions without \(M_A\) constraints. The two-body current contribution considered in this analysis relies on a theoretically effective model and electron scattering experiments and requires future verification by direct measurements and future model improvement.
