31. Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope ArrayM. G. Aartsen, Jon Paul Lundquist, 2016, izvirni znanstveni članek Opis: This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.
Ključne besede: UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy
Objavljeno v RUNG: 30.04.2020; Ogledov: 3355; Prenosov: 0
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32. Study of muons from ultrahigh energy cosmic ray air showers measured with the Telescope Array experimentR.U. Abbasi, Jon Paul Lundquist, 2018, izvirni znanstveni članek Opis: One of the uncertainties in the interpretation of ultrahigh energy cosmic ray data comes from the hadronic interaction models used for air shower Monte Carlo (MC) simulations. The number of muons observed at the ground from ultrahigh energy cosmic ray–induced air showers is expected to depend upon the hadronic interaction model. One may therefore test the hadronic interaction models by comparing the measured number of muons with the MC prediction. In this paper, we present the results of studies of muon densities in ultrahigh energy extensive air showers obtained by analyzing the signal of surface detector stations which should have high muon purity. The muon purity of a station will depend on both the inclination of the shower and the relative position of the station. In seven years’ data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of
∼65% at a lateral distance of 2000 m from the shower core is 1.72±
0.10(stat)±0.37(syst) times larger than the MC prediction value using the QGSJET II-03 model for proton-induced showers. A similar effect is also seen in comparisons with other hadronic models such as QGSJET II-04, which shows a 1.67±0.10±0.36 excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at larger lateral distances.
Ključne besede: UHECR, cosmic rays, muons, particle physics
Objavljeno v RUNG: 30.04.2020; Ogledov: 3378; Prenosov: 0
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33. The Cosmic Ray Energy Spectrum between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular ModeR.U. Abbasi, Jon Paul Lundquist, 2018, izvirni znanstveni članek Opis: We report on a measurement of the cosmic ray energy spectrum by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). The TALE air FD is also sensitive to the Cherenkov light produced by shower particles. Low-energy cosmic rays, in the PeV energy range, are detectable by TALE as Cherenkov events. Using these events, we measure the energy spectrum from a low energy of ~2 PeV to an energy greater than 100 PeV. Above 100 PeV, TALE can detect cosmic rays using air fluorescence. This allows for the extension of the measurement to energies greater than a few EeV. In this paper, we describe the detector, explain the technique, and present results from a measurement of the spectrum using ~1000 hr of observation. The observed spectrum shows a clear steepening near 10^17.1 eV, along with an ankle-like structure at 10^16.2 eV. These features present important constraints on the origin of galactic cosmic rays and on propagation models. The feature at 10^17.1 eV may also mark the end of the galactic cosmic ray flux and the start of the transition to extragalactic sources.
Ključne besede: astroparticle physics, cosmic rays, UHECR, energy spectrum
Objavljeno v RUNG: 30.04.2020; Ogledov: 3434; Prenosov: 0
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34. Search for ultra-high-energy neutrinos with the Telescope Array surface detectorR. U. Abbasi, Mitsuhiro Abe, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, Douglas R. Bergman, S. A. Blake, Jon Paul Lundquist, 2020, izvirni znanstveni članek Opis: We present an upper limit on the flux of ultra-high-energy down-going neutrinos for E > 10^18 eV derived with the nine years of data collected by the Telescope Array surface detector (05-11-2008–
05-10-2017). The method is based on the multivariate analysis technique, so-called Boosted Decision Trees (BDT). Proton-neutrino classifier is built upon 16 observables related to both the properties of the shower front and the lateral distribution function.
Ključne besede: neutrinos, pattern recognition, UHECR, cosmic rays
Objavljeno v RUNG: 29.04.2020; Ogledov: 3986; Prenosov: 77
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35. Air Shower Detection by Bistatic RadarM. Abou Bakr Othman, Jon Paul Lundquist, 2011, objavljeni znanstveni prispevek na konferenci Opis: Progress in the field of high‐energy cosmic rays is currently limited by the rarity of the most interesting rays striking the Earth. Indeed, the continuation of the field beyond the current generation of observatories may become financially and practically impossible if new ways are not found to achieve remote coverage over large portions of the Earth’s surface. We describe the development of an observatory based on such a new technique: the remote sensing via bistatic radar technology of cosmic ray induced extensive air showers. We build on pilot studies performed by MARIACHI which have demonstrated that air shower radar echoes are detectable, the opportunity afforded by the location of the Northern Hemisphere’s largest “conventional” cosmic ray observatory (The Telescope Array) in radio‐quiet western Utah, and the donation of analog television transmission equipment to this effort by a local television station.
Ključne besede: UHECR, Remote sensing, Television broadcasting, Cosmic rays, General procedures and instrumentation, Radar telescopes
Objavljeno v RUNG: 29.04.2020; Ogledov: 3622; Prenosov: 0
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36. TARA: Forward-scattered radar detection of UHECR at the telescope arrayJ. Belz, Jon Paul Lundquist, 2013, objavljeni znanstveni prispevek na konferenci Opis: Increased event statistics will be required to definitively answer the question of the origin(s) of Ultra-High Energy Cosmic Rays (UHECR). Using current technologies however, achieving the necessary statistics may be financially and practically impossible. We describe the status and plans of the TARA project, an effort to detect Ultra-High-Energy Cosmic Rays by their forward scattered or “bistatic” radar signature. Bistatic radar holds promise as a new remote sensing technique for UHECR, without the duty cycle limitations of nitrogen fluorescence detectors. Such a technique could prove key in advancing the study of UHECR beyond the constraints of the current generation of cosmic ray observatories. TARA consists of a low-VHF television transmitter illuminating the air above the Telescope Array (TA), and a set of radio receivers on the far side of TA approximately 50 km distant from the transmitter. We have collected radar data since April 2011 using a 2 kW transmitter at 54.1 MHz. Recently, we received permission to increase our broadcast power to 40 kW and our effective radiated power (ERP) to 6 MW. On the receiver end, we are employing software-defined radio receivers and developing real-time trigger algorithms based on the expected air shower radar echo. In addition to presenting an overview of the project status and future plans, we will present the most recent results of searches for coincidences between radar echoes and Telescope Array air shower events.
Ključne besede: UHECR, cosmic rays, radar detection
Objavljeno v RUNG: 29.04.2020; Ogledov: 3587; Prenosov: 104
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38. Cosmic Ray Shower Profile Track Finding for Telescope Array Fluorescence DetectorsJon Paul Lundquist, 2016, objavljeni znanstveni prispevek na konferenci Opis: A simple cosmic ray track finding pattern recognition analysis (PRA) method for fluorescence detectors (FD) has been developed which significantly improves Xmax resolution and its dependence on energy. Events which have a clear rise and fall in the FD view contain information on Xmax that can be reliably reconstructed. Shower maximum must be extrapolated for events with Xmax outside the field of view of the detector, which creates a systematic dependence on the fitting function. The PRA method is a model and detector independent approach to removing
these events, by fitting shower profiles to a set of triangles and applying limits on the allowable geometry.
Ključne besede: UHECR, cosmic rays, fluorescence detector, track finding, pattern recognition
Objavljeno v RUNG: 29.04.2020; Ogledov: 3766; Prenosov: 114
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40. The Nature and Origin of Ultra-high Energy Cosmic Ray ParticlesP.L. Biermann, Jon Paul Lundquist, 2016, objavljeni znanstveni prispevek na konferenci (vabljeno predavanje) Opis: We outline two concepts to explain Ultra High Energy Cosmic Rays (UHECRs), one based on radio galaxies and their relativistic jets and terminal hot spots, and one based on relativistic Super-Novae (SNe) or Gamma Ray Bursts (GRBs) in starburst galaxies, one matching the arrival direction data in the South (the radio galaxy Cen A) and one in the North (the starburst galaxy M82). The most likely identification of the origin of observed Gravitational Wave (GW) events is stellar binary black hole (BH) mergers in starburst galaxies such as M82 with the highest rate of star formation, so the highest far-infrared (FIR) luminosity, at the edge of the universe visible in 10 - 300 Hz GWs; at low heavy element abundance Zch the formation of stellar BHs extends to a larger mass range. A radio galaxy such as Cen A sequence of events involves first the merger of two Super-Massive Black Holes (SMBHs), with the associated ejection of low frequency GWs, then the formation of a new relativistic jet aiming into a new direction: ubiquitous neutrino emission follows accompanied by compact TeV photon emission, detectable more easily if the direction is towards Earth. The ejection of UHECRs is last. Both these sites are the perfect high energy physics laboratory: We have observed particles up to ZeV, neutrinos up to PeV, photons up to TeV, 30 - 300 Hz GW events, and hope to detect soon of order µHz to mHz GW events. Energy turnover in single low frequency GW events may be of order ∼1063 erg. How can we further test these concepts? First of all by associating individual UHECR events, or directional groups of events, with chemical composition in both the Telescope Array (TA) Coll. and the Auger Coll. data. Second by identifying more TeV
to PeV neutrinos with recent SMBH mergers. Third by detecting the order < mHz GW events of SMBH binaries, and identifying the galaxies host to the stellar BH mergers and their GW events in the range up to 300 Hz. Fourth by finally detecting the formation of the first generation of SMBHs and their mergers, surely a spectacular discovery.
Ključne besede: UHECR, cosmic rays, anisotropy
Objavljeno v RUNG: 29.04.2020; Ogledov: 3234; Prenosov: 129
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