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  1. Prior to 2004, geological sampling in the Arctic Ocean was mainly restricted to near-surface Quaternary sediments. Thus, the long-term pre-Quaternary geological history is still poorly known. With the successful completion of the Arctic Coring Expedition (ACEX) (Integrated Ocean Drilling Program Expedition 302) in 2004, a new era in Arctic research began. Employing a novel multivessel approach, the first mission-specific platform (MSP) expedition of the Integrated Ocean Drilling Program proved that drilling in permanently ice-covered regions is possible. During ACEX, 428 m of Quaternary, Neogene, Paleogene, and Campanian sediment on Lomonosov Ridge were penetrated, providing new and unique insights into Cenozoicmore »Arctic paleoceanographic and climate history. Although it was highly successful, ACEX also had three important limitations. The ACEX sequence contains either a large hiatus spanning the time interval from late Eocene to middle Miocene (based on the original biostratigraphic age model) or an interval of strongly reduced sedimentation rates (based on a more recent Os-Re-isotope-based age model). This is a critical time interval, spanning the time when prominent changes in global climate took place during the transition from the early Cenozoic Greenhouse Earth to the late Cenozoic Icehouse Earth. Furthermore, generally poor recovery during ACEX prevented detailed and continuous reconstruction of Cenozoic climate history. Finally, a higher-resolution reconstruction of Arctic rapid climate change during Neogene and Pleistocene times could not be achieved during ACEX. Therefore, Expedition 377 (Arctic Ocean Paleoceanography [ArcOP]) will return to the Lomonosov Ridge for a second MSP-type drilling campaign with the International Ocean Discovery Program to fill these major gaps in our knowledge on Arctic Ocean paleoenvironmental history through Cenozoic times and its relationship to global climate history. The overall goal of this drilling campaign is to recover a complete stratigraphic sedimentary record of the southern Lomonosov Ridge to meet our highest priority paleoceanographic objective, the continuous long-term Cenozoic climate history of the central Arctic Ocean. Furthermore, sedimentation rates two to four times higher than those of ACEX permit higher-resolution studies of Arctic climate change. The expedition goal can be achieved through careful site selection, the use of appropriate drilling technology and ice management, and by applying multiproxy approaches to paleoceanographic, paleoclimatic, and age-model reconstructions. The expedition will complete one primary deep drill hole (proposed Site LR-11B) to 900 meters below seafloor (mbsf), supplemented by a short drill site (LR-10B) to 50 mbsf, to recover an undisturbed uppermost (Quaternary) sedimentary section. This plan should ensure complete recovery so scientists can construct a composite section that spans the full age range through the Cenozoic.« less
  2. Abstract The Surface Enhancement of the IceTop air-shower array will include the addition of radio antennas and scintillator panels, co-located with the existing ice-Cherenkov tanks and covering an area of about 1 km 2 . Together, these will increase the sensitivity of the IceCube Neutrino Observatory to the electromagnetic and muonic components of cosmic-ray-induced air showers at the South Pole. The inclusion of the radio technique necessitates an expanded set of simulation and analysis tools to explore the radio-frequency emission from air showers in the 70 MHz to 350 MHz band. In this paper we describe the software modules thatmore »have been developed to work with time- and frequency-domain information within IceCube's existing software framework, IceTray, which is used by the entire IceCube collaboration. The software includes a method by which air-shower simulation, generated using CoREAS, can be reused via waveform interpolation, thus overcoming a significant computational hurdle in the field.« less
    Free, publicly-accessible full text available June 1, 2023
  3. Free, publicly-accessible full text available June 1, 2023
  4. Abstract We present a measurement of the high-energy astrophysical muon–neutrino flux with the IceCube Neutrino Observatory. The measurement uses a high-purity selection of 650k neutrino-induced muon tracks from the northern celestial hemisphere, corresponding to 9.5 yr of experimental data. With respect to previous publications, the measurement is improved by the increased size of the event sample and the extended model testing beyond simple power-law hypotheses. An updated treatment of systematic uncertainties and atmospheric background fluxes has been implemented based on recent models. The best-fit single power-law parameterization for the astrophysical energy spectrum results in a normalization of ϕ @ 100more »TeV ν μ + ν ¯ μ = 1.44 − 0.26 + 0.25 × 10 − 18 GeV − 1 cm − 2 s − 1 sr − 1 and a spectral index γ SPL = 2.37 − 0.09 + 0.09 , constrained in the energy range from 15 TeV to 5 PeV. The model tests include a single power law with a spectral cutoff at high energies, a log-parabola model, several source-class-specific flux predictions from the literature, and a model-independent spectral unfolding. The data are consistent with a single power-law hypothesis, however, spectra with softening above one PeV are statistically more favorable at a two-sigma level.« less
    Free, publicly-accessible full text available March 1, 2023
  5. Free, publicly-accessible full text available March 1, 2023
  6. Abstract Ultraluminous infrared galaxies (ULIRGs) have infrared luminosities L IR ≥ 10 12 L ⊙ , making them the most luminous objects in the infrared sky. These dusty objects are generally powered by starbursts with star formation rates that exceed 100 M ⊙ yr −1 , possibly combined with a contribution from an active galactic nucleus. Such environments make ULIRGs plausible sources of astrophysical high-energy neutrinos, which can be observed by the IceCube Neutrino Observatory at the South Pole. We present a stacking search for high-energy neutrinos from a representative sample of 75 ULIRGs with redshift z ≤ 0.13 usingmore »7.5 yr of IceCube data. The results are consistent with a background-only observation, yielding upper limits on the neutrino flux from these 75 ULIRGs. For an unbroken E −2.5 power-law spectrum, we report an upper limit on the stacked flux Φ ν μ + ν ¯ μ 90 % = 3.24 × 10 − 14 TeV − 1 cm − 2 s − 1 ( E / 10 TeV ) − 2.5 at 90% confidence level. In addition, we constrain the contribution of the ULIRG source population to the observed diffuse astrophysical neutrino flux as well as model predictions.« less
    Free, publicly-accessible full text available February 1, 2023
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  8. Free, publicly-accessible full text available October 1, 2022
  9. Free, publicly-accessible full text available April 1, 2023