Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session C09: Sources of Cosmic Rays and NeutrinosLive
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Sponsoring Units: DAP Chair: Tonia Venters, GFSC Room: Roosevelt 4 |
Saturday, April 18, 2020 1:30PM - 1:42PM Live |
C09.00001: Seasonal Variations of multiple-muon events with the NOvA Near Detector Maury Goodman Due to Temperature variations in the upper atmosphere, underground detectors measure more cosmic ray muons in the summer than the winter.~ MINOS unexpectedly measured the opposite situation for multiple-muon events. The underground NOvA Near Detector has confirmed the MINOS observation and studied the effect as a function of zenith angle, muon separation and multiplicity.~ Ideas to understand this effect will be presented. [Preview Abstract] |
Saturday, April 18, 2020 1:42PM - 1:54PM Live |
C09.00002: New insights on the origin of cosmic rays from Auger phase-1 grand finale and advancements from upcoming space probes of the highest energy particles (EUSO-SPB2 and POEMMA) Luis Anchordoqui Auger data provide a compelling indication for a possible correlation between the arrival directions of the highest energy cosmic rays and nearby starburst galaxies. We investigate how this observation impacts our understanding of the cosmic ray origin and discuss what new perception and advancements will come from the looming NASA space probes EUSO-SPB2 and POEMMA. [Preview Abstract] |
Saturday, April 18, 2020 1:54PM - 2:06PM Live |
C09.00003: High-energy neutrino emission from blazar flares Foteini Oikonomou Blazar flares are periods of enhanced high-energy neutrino production according to many theoretical models. Additionally, from an experimental point of view, searches for neutrino emission in temporal coincidence with brief electromagnetic flux enhancements allow increased sensitivity due to being nearly background-free. An interesting indication of neutrino emission during a blazar flare came with the detection of the high-energy neutrino IC170922A in the direction of the blazar TXS 0506+056 during a gamma-ray flare in 2017, which was the first association of a high-energy neutrino with an astrophysical source inconsistent with arising by chance at the 3 sigma level. Motivated by the above considerations, we have calculated the expected high-energy neutrino emission from recently observed, multi-wavelength, blazar flares in the field of view of IceCube. In this talk, I will present the results of our study and describe how the neutrino signal depends on source properties (including the source luminosity, doppler factor, magnetic field strength, presence of external photon fields, and unknown baryon content of the blazar jet) within a standard lepto-hadronic framework. I will also discuss the sensitivity of future neutrino observations to the physical conditions in blazar jets. [Preview Abstract] |
Saturday, April 18, 2020 2:06PM - 2:18PM Live |
C09.00004: Constraining a common origin of the astrophysical neutrino flux and UHECRs Marco Muzio, Glennys Farrar, Michael Unger A quantitative and natural explanation for the ultrahigh-energy cosmic ray spectrum and composition is obtained by considering photonuclear interactions surrounding their sources. In particular this process accounts for both the feature in the particle flux called the "ankle" and the origin of the extragalactic protons below this feature (Unger, Farrar {\&} Anchordoqui 2015). However, such a model does not explain the astrophysical neutrino spectrum observed by IceCube (see Muzio, Unger {\&} Farrar 2019). Here we extend the source model to account for interactions with gas surrounding the site of UHECR acceleration. We perform high-precision simultaneous fits to the UHECR spectrum and composition, and the IceCube astrophysical neutrino flux, for a much more exacting treatment than the qualitative studies in the literature to date. We further explore the possibility of a light component of CRs at the highest energies and study their multi-messenger signatures. [Preview Abstract] |
Saturday, April 18, 2020 2:18PM - 2:30PM Live |
C09.00005: Interpreting Ultrahigh Energy Cosmic-Ray Anisotropies Chen Ding, Noemie Globus, Glennys Farrar The Pierre Auger Observatory reports significant evidence of a large-scale anisotropy in the arrival directions of cosmic rays above 8 EeV, and a hotspot-like anisotropy above 40 EeV. We show that both of these anisotropies naturally arise from sources following the large-scale structure of the Universe, when deflections in extragalactic and Galactic magnetic fields are taken into account. By contrast, the hotspot reported by Telescope Array does not emerge from our large-scale structure model and requires the existence of relatively nearby particular source. A composition close to nitrogen above 40 EeV gives the best fit to the Auger hotspot, and the fit to the dipole anisotropy at lower energy constrains the parameters of extragalactic and Galactic magnetic fields, showing that future refined studies of anisotropy can help learn about diverse physical phenomena. [Preview Abstract] |
Saturday, April 18, 2020 2:30PM - 2:42PM Live |
C09.00006: Source of the highest energy Galactic Cosmic Rays Glennys Farrar, Chen Ding There are multiple strands of evidence for a distinct population of high energy Galactic Cosmic Rays (GCRs), “component B”, consistent with a Peters cycle at energies well beyond the main population of supernova-remnant-accelerated CRs. We present evidence that the source of these GCR’s was a single transient event and identify a possible relic of the event. The consistency of such a scenario with constraints from CR flux, GCR spectral shape and anisotropy, and the rate of known transient event types, will be discussed. [Preview Abstract] |
Saturday, April 18, 2020 2:42PM - 2:54PM Not Participating |
C09.00007: Super GZK'' Particles in a Classic Kramers' Diffusion-over-a-Barrier Model. Samer Alnussirat, Nasser Barghouty, Gary Webb, Peter Biermann We present calculated effects of the dispersion in energy loss in photo-pion reactions on the evolution of ultra-high energy cosmic rays (UHECR) protons' energy spectrum. Based on a Fokker-Planck transport equation in energy space, whose transport coefficients are calculated using laboratory measurements, and a derived Fokker-Planck potential, our results show that dispersion in energy loss has significant effects in estimating the protons' horizon distance as well as their energy spectrum. In particular, the Greisen-Zatsepin -Kuzmin horizon in this formalism is estimated to be less than 80 Mpc.In addition, we demonstrate how a Fokker-Planck-potential formalism can distinguish between protons and heavy ions in observed UHECR. [Preview Abstract] |
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