140 research outputs found

    Sufficere, “It Is Enough”: Avarice vs. Simplicity and Detachment in the Rule of Saint Benedict

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    This paper is an exegesis of selected chapters of the Rule of St. Benedict, specifically chapters thirty-three, thirty-four, fifty-four, fifty-five, and fifty-eight, to examine issues of monastic poverty, private vs. common ownership, avarice, simplicity, detachment, and related issues

    “You Can Become All Flame”: Do the Desert Fathers Have Anything to Say to Us Today?

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    This paper will examine Apophthegmata patrum, the Sayings of the Desert Fathers, in a critical manner, along with selected works from scholars of the Apophthegmata, in the light of recent “popular” treatments of the Apophthegmata, to discuss whether and what the Apophthegmata patrum might have to say to 21st century Christians in the way of timeless truth despite apparent harshness, extremism found in the Apophthegmata, and the fact that approximately seventeen hundred years have fundamentally given us a vastly different way of seeing the world and ourselves in it

    Troubled voices : Choctaws in mass deportation and ethnic cleansing

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    This dissertation is a re-examination of the removal of the Choctaws from Mississippi during the 1830s, through an ethnohistorical lens. It traces the removal process through the divergent perspectives, voices, and experiences of the Choctaws themselves from the dozen years preceding Removal through Removal to Indian Territory, and in so doing, illuminates Choctaw voices, rather than focusing on a strictly political history told as a sequential narrative as has been the case previously throughout the literature. It tells the story of Choctaw removal through the voices and profiles of seven crucially important Choctaw leaders, as well as the stories of ordinary Choctaws from “the Trail of Tears and Death.

    Search for Dark Matter Annihilation in the Galactic Center with IceCube-79

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    The Milky Way is expected to be embedded in a halo of dark matter particles, with the highest density in the central region, and decreasing density with the halo-centric radius. Dark matter might be indirectly detectable at Earth through a flux of stable particles generated in dark matter annihilations and peaked in the direction of the Galactic Center. We present a search for an excess flux of muon (anti-) neutrinos from dark matter annihilation in the Galactic Center using the cubic-kilometer-sized IceCube neutrino detector at the South Pole. There, the Galactic Center is always seen above the horizon. Thus, new and dedicated veto techniques against atmospheric muons are required to make the southern hemisphere accessible for IceCube. We used 319.7 live-days of data from IceCube operating in its 79-string configuration during 2010 and 2011. No neutrino excess was found and the final result is compatible with the background. We present upper limits on the self-annihilation cross-section, \left, for WIMP masses ranging from 30 GeV up to 10 TeV, assuming cuspy (NFW) and flat-cored (Burkert) dark matter halo profiles, reaching down to 41024\simeq 4 \cdot 10^{-24} cm3^3 s1^{-1}, and 2.61023\simeq 2.6 \cdot 10^{-23} cm3^3 s1^{-1} for the νν\nu\overline{\nu} channel, respectively.Comment: 14 pages, 9 figures, Submitted to EPJ-C, added references, extended limit overvie

    Lowering IceCube’s energy threshold for point source searches in the southern sky

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    Observation of a point source of astrophysical neutrinos would be a "smoking gun" signature of a cosmic-ray accelerator. While IceCube has recently discovered a diffuse flux of astrophysical neutrinos, no localized point source has been observed. Previous IceCube searches for point sources in the southern sky were restricted by either an energy threshold above a few hundred TeV or poor neutrino angular resolution. Here we present a search for southern sky point sources with greatly improved sensitivities to neutrinos with energies below 100 TeV. By selecting charged-current nu(mu) interacting inside the detector, we reduce the atmospheric background while retaining efficiency for astrophysical neutrino-induced events reconstructed with sub-degree angular resolution. The new event sample covers three years of detector data and leads to a factor of 10 improvement in sensitivity to point sources emitting below 100 TeV in the southern sky. No statistically significant evidence of point sources was found, and upper limits are set on neutrino emission from individual sources. A posteriori analysis of the highest-energy (similar to 100 TeV) starting event in the sample found that this event alone represents a 2.8 sigma deviation from the hypothesis that the data consists only of atmospheric background

    Search for non-relativistic Magnetic Monopoles with IceCube

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    The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting 1km31\,\mathrm{km}^3 of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the GUT (Grand Unified Theory) era shortly after the Big Bang. These monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of 1027cm210^{-27}\,\mathrm{cm^2} to 1021cm210^{-21}\,\mathrm{cm^2}. In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow-particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of 1022(1024)cm210^{-22}\,(10^{-24})\,\mathrm{cm^2} the flux of non-relativistic GUT monopoles is constrained up to a level of Φ901018(1017)cm2s1sr1\Phi_{90} \le 10^{-18}\,(10^{-17})\,\mathrm{cm^{-2}s^{-1}sr^{-1}} at a 90% confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections.Comment: 20 pages, 20 figure

    The contribution of Fermi-2LAC blazars to the diffuse TeV-PeV neutrino flux

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    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 27%27 \% 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 2.5-2.5. We can still exclude that the 2LAC blazars (and sub-populations) emit more than 50%50 \% of the observed neutrinos up to a spectral index as hard as 2.2-2.2 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 γ\gamma-ray signal for each source. Additionally, we constrain recent models for neutrino emission by blazars.Comment: 18 pages, 22 figure

    The IceCube Neutrino Observatory - Contributions to ICRC 2015 Part II: Atmospheric and Astrophysical Diffuse Neutrino Searches of All Flavors

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    Papers on atmospheric and astrophysical diffuse neutrino searches of all flavors submitted to the 34th International Cosmic Ray Conference (ICRC 2015, The Hague) by the IceCube Collaboration.Comment: 66 pages, 36 figures, Papers submitted to the 34th International Cosmic Ray Conference, The Hague 2015, v2 has a corrected author lis

    A combined maximum-likelihood analysis of the high-energy astrophysical neutrino flux measured with IceCube

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    Evidence for an extraterrestrial flux of high-energy neutrinos has now been found in multiple searches with the IceCube detector. The first solid evidence was provided by a search for neutrino events with deposited energies 30\gtrsim30 TeV and interaction vertices inside the instrumented volume. Recent analyses suggest that the extraterrestrial flux extends to lower energies and is also visible with throughgoing, νμ\nu_\mu-induced tracks from the Northern hemisphere. Here, we combine the results from six different IceCube searches for astrophysical neutrinos in a maximum-likelihood analysis. The combined event sample features high-statistics samples of shower-like and track-like events. The data are fit in up to three observables: energy, zenith angle and event topology. Assuming the astrophysical neutrino flux to be isotropic and to consist of equal flavors at Earth, the all-flavor spectrum with neutrino energies between 25 TeV and 2.8 PeV is well described by an unbroken power law with best-fit spectral index 2.50±0.09-2.50\pm0.09 and a flux at 100 TeV of (6.71.2+1.1)1018GeV1s1sr1cm2\left(6.7_{-1.2}^{+1.1}\right)\cdot10^{-18}\,\mathrm{GeV}^{-1}\mathrm{s}^{-1}\mathrm{sr}^{-1}\mathrm{cm}^{-2}. Under the same assumptions, an unbroken power law with index 2-2 is disfavored with a significance of 3.8 σ\sigma (p=0.0066%p=0.0066\%) with respect to the best fit. This significance is reduced to 2.1 σ\sigma (p=1.7%p=1.7\%) if instead we compare the best fit to a spectrum with index 2-2 that has an exponential cut-off at high energies. Allowing the electron neutrino flux to deviate from the other two flavors, we find a νe\nu_e fraction of 0.18±0.110.18\pm0.11 at Earth. The sole production of electron neutrinos, which would be characteristic of neutron-decay dominated sources, is rejected with a significance of 3.6 σ\sigma (p=0.014%p=0.014\%).Comment: 16 pages, 10 figures; accepted for publication in The Astrophysical Journal; updated one referenc

    The search for transient astrophysical neutrino emission with IceCube-DeepCore

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    We present the results of a search for astrophysical sources of brief transient neutrino emission using IceCube and DeepCore data acquired between 2012 May 15 and 2013 April 30. While the search methods employed in this analysis are similar to those used in previous IceCube point source searches, the data set being examined consists of a sample of predominantly sub-TeV muon-neutrinos from the Northern Sky (-5 degrees < delta < 90 degrees) obtained through a novel event selection method. This search represents a first attempt by IceCube to identify astrophysical neutrino sources in this relatively unexplored energy range. The reconstructed direction and time of arrival of neutrino events are used to search for any significant self-correlation in the data set. The data revealed no significant source of transient neutrino emission. This result has been used to construct limits at timescales ranging from roughly 1 s to 10 days for generic soft-spectra transients. We also present limits on a specific model of neutrino emission from soft jets in core-collapse supernovae
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