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21.
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 Array
M. 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: 2487; Prenosov: 0
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22.
Energy-position correlation anisotropy of ultra-high energy cosmic rays with Telescope Array Data
Jon Paul Lundquist, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Indication of an energy dependent intermediate-scale anisotropy has been found in the arrival directions of ultra-high energy cosmic rays with energies above 20 EeV in the northern hemisphere, using 7 years of TA surface detector data. The previously reported “hotspot“ excess for E>57 EeV is found to correspond to a deficit, or “coldspot“, of events for energies 2057 EeV has a Li-Ma statistical significance of 4.62σ, and the deficit for energies 20Ključne besede: UHECR, energy spectrum, anisotropy, magnetic deflection
Objavljeno v RUNG: 29.04.2020; Ogledov: 2654; Prenosov: 0
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23.
The Nature and Origin of Ultra-high Energy Cosmic Ray Particles
P.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: 2349; Prenosov: 123
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24.
Telescope Array anisotropy summary
M. Fukushima, Jon Paul Lundquist, 2018, objavljeni znanstveni prispevek na konferenci

Opis: The Telescope Array has accumulated the largest UHECR data set in the Northern hemisphere. We make use of these data to search for large- and small-scale anisotropy of UHECR arrival directions. At small angular scales, we report an update on searches for clustering of events and on correlations with various classes of putative sources. At large angular scales, we revisit, with the new data and with new tests, the localized excess of events known as the TA “hot spot”. We review some other studies of the arrival directions and corresponding implications for the nature of UHECR sources.
Ključne besede: UHECR, cosmic rays, anisotropy
Objavljeno v RUNG: 29.04.2020; Ogledov: 2433; Prenosov: 86
.pdf Celotno besedilo (581,87 KB)

25.
Evidence of Intermediate-Scale Energy Spectrum Anisotropy of Cosmic Rays E>10^19.2 eV with the Telescope Array Surface Detector
Jon Paul Lundquist, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Evidence of an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays of energies above 10^19.2 eV in the northern hemisphere, using 7 years of Telescope Array (TA) surface detector (SD) data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 139 R.A., 45 Dec., and has a deficit of events with energies 10^19.210^19.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo (MC) simulation to be 9x10^-5 (3.74 σ_global).
Ključne besede: UHECR, cosmic rays, energy spectrum, anisotropy
Objavljeno v RUNG: 29.04.2020; Ogledov: 2547; Prenosov: 82
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26.
Evidence of Intermediate-Scale Energy Spectrum Anisotropy in the Northern Hemisphere from Telescope Array
Jon Paul Lundquist, 2018, objavljeni znanstveni prispevek na konferenci

Opis: Evidence of an energy dependent intermediate-scale anisotropy has been found in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere, using 7 years of TA surface detector data. The previously reported ``hot spot" excess E ≥ 10^19.75 EeV is found to correspond to a deficit, or ``cold spot," of events for 10^19.2≤ E < 10^19.75 EeV. This feature suggests energy dependent magnetic deflection of cosmic-rays. The global post-trial significance of the energy spectrum deviation is found to be 3.74σ.
Ključne besede: UHECR, cosmic rays, energy spectrum, anisotropy, magnetic deflection
Objavljeno v RUNG: 28.04.2020; Ogledov: 2673; Prenosov: 79
.pdf Celotno besedilo (4,87 MB)

27.
Telescope Array Hot/Coldspot Study – Intermediate Scale Anisotropy
Jon Paul Lundquist, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Indications of energy dependent intermediate scale anisotropy has been found in the arrival directions of ultra high energy cosmic rays with energies above 20 EeV in the northern hemisphere, using 7 years of TA surface detector data. The previously reported “hotspot‘” excess for E>57 EeV is found to correspond to a deficit, or “coldspot ”, of events for energies 2057 EeV has a Li Ma statistical significance of 4.62σ, and the deficit for energies 20Ključne besede: cosmic rays, energy spectrum, anisotropy, magnetic deflection
Objavljeno v RUNG: 28.04.2020; Ogledov: 2665; Prenosov: 0
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28.
Updated Results on the UHECR Hotspot Observed by the Telescope Array Experiment
K. Kawata, Jon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci

Opis: The Telescope Array Experiment has observed an indication of intermediate-scale anisotropy in the UHECR arrival directions, called the Hotspot, with E>57 EeV around the Ursa Major using the first 5-year data during a period between May 2008 and May 2013 collected by the TA surface detector array. The chance probability of this hotspot in an isotropic cosmic-ray sky was calculated to be 3.4σ (post trial). In this paper, we will report on an update of this result using the 11-year data collected by the TA surface detectors with more than doubled exposure since the first publication.
Ključne besede: UHECR, cosmic rays, anisotropy
Objavljeno v RUNG: 28.04.2020; Ogledov: 2402; Prenosov: 80
.pdf Celotno besedilo (934,91 KB)

29.
TA Anisotropy Summary
K. Kawata, Jon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci

Opis: The Telescope Array (TA) is the largest ultra-high-energy cosmic-ray (UHECR) detector in the northern hemisphere. It consists of an array of 507 surface detectors (SD) covering a total 700 km^2 and three fluorescence detector stations overlooking the SD array. In this proceedings, we summarize recent results on the search for directional anisotropy of UHECRs using the latest dataset collected by the TA SD array. We obtained hints of the anisotropy of the UHECRs in the northern sky from the various analyses.
Ključne besede: cosmic radiation, UHE detector, fluorescence detector, surface, Telescope Array Experiment, anisotropy, experimental results
Objavljeno v RUNG: 28.04.2020; Ogledov: 2852; Prenosov: 78
.pdf Celotno besedilo (1,88 MB)

30.
Covering the celestial sphere at ultra-high energies: Full-sky cosmic-ray maps beyond the ankle and the flux suppression
J. Biteau, Jon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci

Opis: Despite deflections by Galactic and extragalactic magnetic fields, the distribution of ultra-high energy cosmic rays (UHECRs) over the celestial sphere remains a most promising observable for the identification of their sources. Thanks to a large number of detected events over the past years, a large-scale anisotropy at energies above 8 EeV has been identified, and there are also indications from the Telescope Array and Pierre Auger Collaborations of deviations from isotropy at intermediate angular scales (about 20 degrees) at the highest energies. In this contribution, we map the flux of UHECRs over the full sky at energies beyond each of two major features in the UHECR spectrum – the ankle and the flux suppression, and we derive limits for anisotropy on different angular scales in the two energy regimes. In particular, full-sky coverage enables constraints on low-order multipole moments without assumptions about the strength of higher-order multipoles. Following previous efforts from the two Collaborations, we build full-sky maps accounting for the relative exposure of the arrays and differences in the energy normalizations. The procedure relies on cross-calibrating the UHECR fluxes reconstructed in the declination band around the celestial equator covered by both observatories. We present full-sky maps at energies above ~10 EeV and ~50 EeV, using the largest datasets shared across UHECR collaborations to date. We report on anisotropy searches exploiting full-sky coverage and discuss possible constraints on the distribution of UHECR sources.
Ključne besede: UHECR, cosmic rays, anisotropy, Telescope Array, Pierre Auger Observatory
Objavljeno v RUNG: 28.04.2020; Ogledov: 2483; Prenosov: 82
.pdf Celotno besedilo (4,92 MB)

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