| 1. |
- Abbasi, R., et al.
(författare)
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A Combined Fit of the Diffuse Neutrino Spectrum using IceCube Muon Tracks and Cascades
- 2022
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Ingår i: 37th International Cosmic Ray Conference (ICRC 2021). - Trieste, Italy : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- The IceCube Neutrino Observatory first observed a diffuse flux of high energy astrophysical neutrinos in 2013. Since then, this observation has been confirmed in multiple detection channels such as high energy starting events, cascades, and through-going muon tracks. Combining these event selections into a high statistics global fit of 10 years of IceCube's neutrino data could strongly improve the understanding of the diffuse astrophysical neutrino flux: challenging or confirming the simple unbroken power-law flux model as well as the astrophysical neutrino flux composition. One key component of such a combined analysis is the consistent modelling of systematic uncertainties of different event selections. This can be achieved using the novel SnowStorm Monte Carlo method which allows constraints to be placed on multiple systematic parameters from a single simulation set. We will report on the status of a new combined analysis of through-going muon tracks and cascades. It is based on a consistent all flavor neutrino signal and background simulation using, for the first time, the SnowStorm method to analyze IceCube's high-energy neutrino data. Estimated sensitivities for the energy spectrum of the diffuse astrophysical neutrino flux will be shown.
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| 2. |
- Abbasi, R., et al.
(författare)
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A model-independent analysis of neutrino flares detected in IceCube from X-ray selected blazars
- 2022
-
Ingår i: 37th International Cosmic Ray Conference, ICRC2021. - Trieste, Italy : Proceedings of Science.
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Konferensbidrag (refereegranskat)abstract
- Blazars are among the most powerful steady sources in the Universe. Multi-messenger searches for blazars have traditionally focused on their gamma-ray emission, which can be produced simultaneously with neutrinos in photohadronic interactions. However, X-ray data can be equally vital to constrain the SED of these sources, since the hadronically co-produced gamma-rays could get absorbed by the ambient photon fields and cascade down to X-ray energies before escaping. In this work, we present the outline for an untriggered, time-dependent analysis of neutrino flares from the direction of X-ray selected blazars using 10 years of IceCube data. A binomial test will be performed on the population to reveal if a subcategory of sources has statistically significant emission. The sources are selected from RomaBZCat, and the p-values and best-fit flare parameters are obtained for each source using the method of unbinned likelihood maximisation.
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| 3. |
- Abbasi, R., et al.
(författare)
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A New Search for Neutrino Point Sources with IceCube
- 2022
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Ingår i: 37th International Cosmic Ray Conference (ICRC 2021). - Trieste, Italy : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- The IceCube Neutrino Observatory, deployed inside the deep glacial ice at the South Pole, is the largest neutrino telescope in the world. While eight years have passed since IceCube discovered a diffuse flux of high-energy astrophysical neutrinos, the sources of the vast majority of these neutrinos remain unknown. Here, we present a new search for neutrino point sources that improves the accuracy of the statistical analysis, especially in the low energy regime. We replaced the usual Gaussian approximations of IceCube's point spread function with precise numerical representations, obtained from simulations, and combined them with new machine learning-based estimates of event energies and angular errors. Depending on the source properties, the new analysis provides improved source localization, flux characterization and thereby discovery potential (by up to 30%) over previous works. The analysis will be applied to IceCube data that has been recorded with the full 86-string detector configuration from 2011 to 2020 and includes improved detector calibration.
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| 4. |
- Abbasi, R., et al.
(författare)
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A next-generation optical sensor for IceCube-Gen2
- 2022
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Ingår i: 37th International Cosmic Ray Conference, ICRC2021. - Trieste, Italy : Proceedings of Science.
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Konferensbidrag (refereegranskat)abstract
- For the in-ice component of the next generation neutrino observatory at the South Pole, IceCube-Gen2, a new sensor module is being developed, which is an evolution of the D-Egg and mDOM sensors developed for the IceCube Upgrade. The sensor design features up to 18 4-inch PMTs distributed homogeneously in a borosilicate glass pressure vessel. Challenges arise for the mechanical design from the tight constraints on the bore hole diameter (which will be 2 inches smaller than for IceCube Upgrade) and from the close packing of the PMTs. The electronics design must meet the space constraints posed by the mechanical design as well as the power consumption and cost considerations from over 10,000 optical modules being deployed. This contribution presents forward-looking solutions to these design considerations. Prototype modules will be installed and integrated in the IceCube Upgrade.
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| 5. |
- Abbasi, R., et al.
(författare)
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A novel microstructure-based model to explain the IceCube ice anisotropy
- 2022
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Ingår i: 37th International Cosmic Ray Conference, ICRC2021. - Trieste, Italy : Proceedings of Science.
-
Konferensbidrag (refereegranskat)abstract
- The IceCube Neutrino Observatory instruments about 1 km(3) of deep, glacial ice at the geographic South Pole using 5160 photomultipliers to detect Cherenkov light of charged relativistic particles. Most of IceCube's science goals rely heavily on an ever more precise understanding of the optical properties of the instrumented ice. A curious light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow of the ice. Having recently identified curved photon trajectories resulting from asymmetric light diffusion in the birefringent polycrystalline microstructure of the ice as the most likely underlying cause of this effect, work is now ongoing to optimize the model parameters (effectively deducing the average crystal size and shape in the detector). We present the parametrization of the birefringence effect in our photon propagation simulation, the fitting procedures and results as well as the impact of the new ice model on data-MC agreement.
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| 6. |
- Abbasi, R., et al.
(författare)
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A Posterior Analysis on IceCube Double Pulse Tau Neutrino Candidates
- 2022
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Ingår i: 37th International Cosmic Ray Conference, ICRC 2021. - Trieste, Italy : Proceedings of Science.
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Konferensbidrag (refereegranskat)abstract
- The IceCube Neutrino Observatory at the South Pole detects Cherenkov light emitted by charged secondary particles created by primary neutrino interactions. Double pulse waveforms can arise from charged current interactions of astrophysical tau neutrinos with nucleons in the ice and the subsequent decay of tau leptons. The previous 8-year tau double pulse analysis found three tau neutrino candidate events. Among them, the most promising one observed in 2014 is located very near the dust layer in the middle of the detector. A posterior analysis on this event will be presented in this paper, using a new ice model treatment with continuously varying nuisance parameters to do the targeted Monte Carlo re-simulation for tau and other background neutrino ensembles. The impact of different ice models on the expected signal and background statistics will also be discussed.
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| 7. |
- Abbasi, R., et al.
(författare)
-
A Search for Neutrinos from Decaying Dark Matter in Galaxy Clusters and Galaxies with IceCube
- 2022
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Ingår i: 37th International Cosmic Ray Conference, ICRC2021. - : Proceedings of Science.
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Konferensbidrag (refereegranskat)abstract
- 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 collected a large amount of astrophysical neutrino data with energies up to tens of PeV, allowing us to probe the heavy dark matter models using neutrinos. We search the IceCube data for neutrinos from decaying dark matter in galaxy clusters and galaxies. The targeted dark matter masses range from 10 TeV to 10 PeV. In this contribution, we present the method and sensitivities of the analysis.
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| 8. |
- Abbasi, R., et al.
(författare)
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A time-independent search for neutrinos from galaxy clusters with IceCube
- 2022
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Ingår i: 37th International Cosmic Ray Conference (ICRC 2021). - Trieste, Italy : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- Clusters of galaxies - with their turbulent magnetic fields and abundant matter content - are a promising class of potential neutrino sources. Cosmic rays accelerated within the large-scale shocks, Active GalacticNuclei (AGN), or both can be confined in galaxy clusters over cosmological timescales and produce a steady flux of neutrinos in secondary interactions. The IceCube Neutrino Observatory has detected a diffuse flux of high-energy astrophysical neutrinos. After ten years of operations, however, the origin of this flux remains largely unconstrained. In this work, we perform a stacked search for neutrinos, using a population of over one thousand galaxy clusters detected by the Planck Satellite via the Sunyaev-Zeldovich (SZ) effect up to a redshift z = 1. We present the first results on the contribution of galaxy clusters to the diffuse neutrino flux and discuss the implications for various models of cosmic-ray acceleration in large-scale structures.
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| 9. |
- Abbasi, R., et al.
(författare)
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A Time-Variability Test for Candidate Neutrino Sources Observed with IceCube
- 2022
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Ingår i: 37th International Cosmic Ray Conference (ICRC 2021). - Trieste, Italy : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- Recent studies with IceCube have shown signs of a time-integrated flux of astrophysical neutrinos from point-like sources such as TXS 0506+056 and NGC 1068. Time-variability of this neutrino emission from TXS 0506+056 has been studied extensively by assuming a temporal profile of the possible flare(s) or searching for temporal neutrino correlation with other electromagnetic counterparts. However, experimental evidence of the temporal profile of an astrophysical neutrino signal, besides the TXS 0506+056 source, remains lacking. In this study, we present a new KS-test based method for investigating time-variability. This new method complements the existing time-dependent search methods with a test for arbitrary time-variability, independent of an assumed temporal profile or electromagnetic counterpart. Additionally, this method provides a diagnostic tool for characterizing point-like source candidates in IceCube by distinguishing variable from steady neutrino emission and we show results of applying this method to a small catalog of candidate blazars.
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| 10. |
- Abbasi, R., et al.
(författare)
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Analysis framework for Multi-messenger Astronomy with IceCube
- 2022
-
Ingår i: 37th International Cosmic Ray Conference, ICRC2021. - Trieste, Italy : Proceedings of Science.
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Konferensbidrag (refereegranskat)abstract
- 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 use of neutrino data in multi-messenger astronomy. In this work we illustrate how to use the i3mla package with 3ML and present preliminary sensitivities using the i3mla package and 3ML through a joint-fit with HAWC Public dataset.
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