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Abstract To study the average contributions of the cusp outflow through the lobes and of the nightside auroral outflow to the O⁺in the plasma sheet (PS), we performed a statistical study of tailward streaming O⁺in the lobes, plasma sheet boundary layer|the plasma sheet boundary layer (PSBL) and the PS, using MMS/Hot Plasma Composition Analyzer (HPCA) data from 2017 to 2020. Similar spatial patterns illustrate the entry of cusp‐origin O⁺from the lobes to the PS through the PSBL. There is an Y_GSM‐dependent energy pattern for the lobe O⁺, with low‐energy O⁺streaming closer to the tail center and high energy (1–3 keV) O⁺streaming near the flanks. Low energy (1–100 eV) O⁺from the nightside auroral oval is identified in the near‐Earth PSBL/PS with high‐density (>0.02 cm⁻³), and energetic (>3 keV) streaming O⁺with similar density (∼0.013 cm⁻³) is observed further out on the duskside of the PSBL/PS. The rest of the nightside auroral O⁺in the PSBL is mixed with O⁺coming in from the lobe, making it difficult to distinguish the source. We estimated the contributions of the different sources of H⁺and O⁺ions through the PS between 7 and 17 R_E, using estimates from this work and data extracted from previous studies. We conclude that, during quiet times, the majority of the near‐Earth PS H⁺are from the cusps, the polar wind and Earthward convection from the distant tail. Similarly, while the O⁺in the same region has a mixed source, cusp origin outflow provides the highest contribution. 

Abstract The recent IceCube detection of TeV neutrino emission from the nearby active galaxy NGC 1068 suggests that active galactic nuclei (AGNs) could make a sizable contribution to the diffuse flux of astrophysical neutrinos. The absence of TeVγ-rays from NGC 1068 indicates neutrino production in the vicinity of the supermassive black hole, where the high radiation density leads toγ-ray attenuation. Therefore, any potential neutrino emission from similar sources is not expected to correlate with high-energyγ-rays. Disk-corona models predict neutrino emission from Seyfert galaxies to correlate with keV X-rays because they are tracers of coronal activity. Using through-going track events from the Northern Sky recorded by IceCube between 2011 and 2021, we report results from a search for individual and aggregated neutrino signals from 27 additional Seyfert galaxies that are contained in the Swift's Burst Alert Telescope AGN Spectroscopic Survey. Besides the generic single power law, we evaluate the spectra predicted by the disk-corona model assuming stochastic acceleration parameters that match the measured flux from NGC 1068. Assuming all sources to be intrinsically similar to NGC 1068, our findings constrain the collective neutrino emission from X-ray bright Seyfert galaxies in the northern sky, but, at the same time, show excesses of neutrinos that could be associated with the objects NGC 4151 and CGCG 420-015. These excesses result in a 2.7σsignificance with respect to background expectations. 

We report a study of the inelasticity distribution in the scattering of neutrinos of energy 80–560 GeV off nucleons. Using atmospheric muon neutrinos detected in IceCube’s sub-array DeepCore during 2012–2021, we fit the observed inelasticity in the data to a parameterized expectation and extract the values that describe it best. Finally, we compare the results to predictions from various combinations of perturbative QCD calculations and atmospheric neutrino flux models. Published by the American Physical Society2025