1. Indications of anisotropy at large angular scales in the arrival directions of cosmic rays detected at the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Imen Al Samarai, 2015, published scientific conference contribution Abstract: The large-scale distribution of arrival directions of
high-energy cosmic rays carries major clues to understanding
their origin. The Pierre Auger Collaboration have implemented
different analyses to search for dipolar and quadrupolar
anisotropies in different energy ranges spanning four orders
of magnitude. A common phase ≈270◦ of the first harmonic
modulation in right-ascension was found in adjacent energy intervals below 1 EeV, and another common phase ≈100◦
above 4 EeV. A constancy of phase measurements in ordered
energy intervals originating from a genuine anisotropy is
expected to appear with a smaller number of events than those
needed to achieve significant amplitudes. This led us to
design a prescribed test aimed at establishing whether
this consistency in phases is real at 99% CL. The test required
a total independent exposure of 21,000 km2 sr yr. We report on
the status of this prescription. We also report the results of
the search for a dipole anisotropy for cosmic rays with
energies above 4 EeV using events with zenith angles between
60◦ and 80◦. Compared to previous analyses of events with
zenith angles smaller than 60◦, this extension increases
the size of the data set by 30%, and enlarges the fraction of
exposed sky from 71% to 85%. The largest departure from
isotropy is found in the energy range above 8 EeV, with an
amplitude for the first harmonic in right ascension
r1 = (4.4 ± 1.0) × 10[sup]−2, that has a chance probability
P(≥ r1) = 6.4×10[sup]−5, reinforcing the hint previously
reported with vertical events alone.
Found in: ključnih besedah
Summary of found: ...The large-scale distribution of arrival directions of
high- energy cosmic rays carries major clues to understanding...
Keywords: high-energy cosmic rays
large-scale distribution
anisotropy studies
Pierre Auger Observatory
Published: 02.03.2016; Views: 2258; Downloads: 164
 Fulltext (862,90 KB) |
2. Large-Scale Distribution of Arrival Directions of Cosmic Rays Detected at the Pierre Auger Observatory and the Telescope Array above 10[sup]19 eVMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Olivier Deligny, 2015, published scientific conference contribution Abstract: The large-scale distribution of arrival directions of
high-energy cosmic rays is a key observable in attempts to
understanding their origin. The dipole and quadrupole moments
are of special interest in revealing potential anisotropies.
An unambiguous measurement of these moments as well as
of the full set of spherical harmonic coefficients requires
full-sky coverage. This can be achieved by combining data from
observatories located in both the northern and southern
hemispheres. To this end, a joint analysis using data recorded
at the Pierre Auger Observatory and the Telescope Array above
10[sup]19 eV has been performed. Thanks to the full-sky
coverage, the measurement of the dipole moment reported in
this study does not rely on any assumption on the underlying
flux of cosmic rays. As well, the resolution on the quadrupole
and higher order moments is the best ever obtained. The
resulting multipolar expansion of the flux of cosmic rays
allows a series of anisotropy searches to be performed,
and in particular to report on the first angular power
spectrum of cosmic rays. This allows a comprehensive
description of the angular distribution of cosmic rays
above 10[sup]19 eV.
Found in: ključnih besedah
Summary of found: ...The large-scale distribution of arrival directions of
high- energy cosmic rays is a key observable in...
Keywords: Pierre Auger Observatory, Telescope Array, high-energy cosmic rays, large-scale anisotropies, angular power spectrum
Published: 08.03.2016; Views: 2004; Downloads: 121
Fulltext (462,61 KB) |
3. A new method to determine the energy scale for high-energy cosmic rays using radio measurements at the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Raphael Krause, 2017, published scientific conference contribution Found in: ključnih besedah
Keywords: energy scale, cosmic rays, radio measurements, Pierre Auger Observatory
Published: 16.02.2018; Views: 1019; Downloads: 81
Fulltext (3,64 MB) |
4. Supergalactic Structure of Energy-Angle CorrelationsP. Sokolsky, J. P. Lundquist, 2020, published scientific conference contribution Abstract: Evidence for the supergalactic structure of multiplets (energy-angle correlations) has previously been shown using ultra-high energy cosmic ray (UHECR) data from Telescope Array (TA) with energies above 10^19 eV. The supergalactic deflection hypothesis (that UHECR sources and intervening magnetic fields are correlated) is measured by the all-sky behavior of the strength of
intermediate-scale correlations. The multiplets are measured in spherical surface wedge bins of the field-of-view to account for uniform and random magnetic fields. The structure found is consistent with the previously published energy spectrum anisotropy results of TA and toy-model simulations of a supergalactic magnetic sheet. The 7 year data post-trial significance of this feature appearing by chance, on an isotropic sky, was found by Monte Carlo simulation to be ∼4σ. The analysis has now been applied to 10 years of data.
Found in: ključnih besedah
Summary of found: ...by the all-sky behavior of the strength of
intermediate- scale correlations. The multiplets are measured in spherical...
Keywords: Cosmic rays, UHECR, energy spectrum, magnetic deflection, large-scale structure, supergalactic, multiplets
Published: 27.04.2020; Views: 422; Downloads: 18
Fulltext (1,66 MB) |
5. Supergalactic Structure of Multiplets with the Telescope Array Surface DetectorP. Sokolsky, J. P. Lundquist, 2019, published scientific conference contribution Abstract: Evidence of supergalactic structure of multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 10^19 eV using 7 years of data from the Telescope Array (TA) surface detector. The tested hypothesis is that UHECR sources, and intervening magnetic fields, may be correlated with the supergalactic plane, as it is a fit to the average matter density within the GZK horizon. This structure is measured by the average behavior of the strength of intermediate-scale correlations between event energy and position (multiplets). These multiplets are measured in wedge-like shapes on the spherical surface of the fieldof-view to account for uniform and random magnetic fields. The evident structure found is consistent with toy-model simulations of a supergalactic magnetic sheet and the previously published Hot/Coldspot results of TA. The post-trial probability of this feature appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be ~4.5σ.
Found in: ključnih besedah
Summary of found: ...of multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 10^19... ...the average behavior of the strength of intermediate- scale correlations between event energy and position (multiplets)....
Keywords: UHECR, cosmic rays, energy spectrum, anisotropy, large-scale structure, magnetic deflection
Published: 28.04.2020; Views: 450; Downloads: 27
Fulltext (1,38 MB) |
6. The Energy Scale of the Pierre Auger ObservatoryLukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Bruce R. Dawson, 2019, published scientific conference contribution Found in: ključnih besedah
Keywords: ultra-high energy cosmic rays, Pierre Auger Observatory, energy scale
Published: 16.06.2020; Views: 300; Downloads: 15
Fulltext (277,08 KB) |
7. Large-scale anisotropies above 0.03 EeV measured by the Pierre Auger ObservatoryLukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Esteban Roulet, 2019, published scientific conference contribution Found in: ključnih besedah
Summary of found: ...ultra-high energy cosmic rays (UHECRs), Pierre Auger Observatory, UHECR...
Keywords: ultra-high energy cosmic rays (UHECRs), Pierre Auger Observatory, UHECR arrival directions, large-scale anisotropies
Published: 24.07.2020; Views: 328; Downloads: 14
Fulltext (894,55 KB) |
