211. Update of the neutrino and photon limits from the Pierre Auger ObservatoryCarla Bleve, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: Ultra-high energy neutrinos and photons, with energies above
1 EeV and 10 EeV respectively, can be detected with the Surface
Detector array (SD) of the Pierre Auger Observatory. Downward-
going neutrinos of all flavours interacting in the atmosphere
at zenith angles θ > 60◦, upward-going tau neutrinos (“Earth-
skimming”), as well as photons in the zenith range 30◦ − 60◦
can be identified through the broad time-structure of the
signals expected to be induced in the SD stations. An
additional signature for photon-induced air showers is the
steeper lateral distribution of secondary particles at ground
with respect to the nucleonic showers. Stringent limits are set
to the diffuse flux of ultra-high energy (UHE) neutrinos and
photons, using data collected between 2004 and mid-2013, under
the hypothesis of an E[sup]−2 spectrum for signal primaries.
Keywords: ultra-high energy neutrinos, ultra-high energy photons, cosmic rays, elemental composition, Pierre Auger Observatory
Published in RUNG: 03.03.2016; Views: 5849; Downloads: 242
 Full text (398,21 KB) |
212. Composition at the “ankle” measured by the Pierre Auger Observatory: pure or mixed?Alexey Yushkov, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: We report for the first time on the measurement of the
correlation between the depth of shower maximum and the signal
in water-Cherenkov stations for events reconstructed by both
the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlated measurement is a unique feature
of a hybrid air-shower observatory and allows us to determine
the purity of the cosmic-ray composition. The observed
correlation in the energy range around the “ankle”
lg(E/eV) = 18.5−19.0 differs significantly from the expectations for pure beams, indicating that the primary composition in this range is mixed, unless the
hadronic interactions at these energies behave very
differently than in conventional, LHC-tuned event generators.
Keywords: ultra-high energy cosmic rays, elemental composition, depth of shower maximum, secondary cosmic rays, Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 6322; Downloads: 244
Full text (388,00 KB) |
213. Search for energy dependent patterns in the arrival direction of cosmic rays at the Pierre Auger ObservatoryTobias Winchen, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: Energy-dependent patterns in the arrival directions of cosmic
rays are expected from deflections in galactic and extragalactic magnetic fields. We report on searches for such
patterns in the data of the surface detector of the Pierre
Auger Observatory at energies above E = 5 EeV in regions
within approximately 15◦ around events with energy E > 60
EeV. No significant patterns are found with this analysis which
can be used to constrain parameters in propagation scenarios.
Keywords: ultra-high energy cosmic rays
galactic and extragalactic magnetic fields
magnetic deflection patterns
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 6439; Downloads: 230
Full text (1019,52 KB) |
214. Arrival directions of the highest-energy cosmic rays detected with the Pierre Auger ObservatoryJulien Aublin, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: We present the results of a search for small to intermediate
scale anisotropies in the distribution of arrival directions
of ultra-high energy cosmic rays recorded at the Pierre Auger
Observatory. The data set, gathered in ten years of operation,
includes arrival directions with zenith angles up to 80◦,
and is about three times larger than that used in earlier
studies. We update the test based on correlations with active
galactic nuclei (AGNs) from the Véron-Cetty and Véron catalog,
which does not yield a significant indication of anisotropy
with the present data set. We perform a blind search for
localized excess fluxes and for self-clustering of arrival
directions at angular scales up to 30◦ and for different
energy thresholds between 40 EeV and 80 EeV. We also examine
the correlation of arrival directions with relatively nearby galaxies in the 2MRS catalog, AGNs detected by Swift-BAT,
and a sample of radio galaxies with jets and with the
Centaurus A galaxy. None of the searches shows a statistically
significant evidence of anisotropy. The two largest
departures from isotropy that were found have a post-trial
probability ≈ 1.4%. One is for cosmic rays with energy above
58 EeV that arrive within 15◦ of the direction toward
Centaurus A. The other is for arrival directions within 18◦
of Swift-BAT AGNs closer than 130 Mpc and brighter than
10[sup]44 erg/s, with the same energy threshold.
Keywords: ultra-high energy cosmic rays
anisotropy studies
active galactic nuclei
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 6139; Downloads: 234
Full text (1,32 MB) |
215. The flux of ultra-high energy cosmic rays after ten years of operation of the Pierre Auger ObservatoryInés Valiño, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: The flux of ultra-high energy cosmic rays has been measured
with unprecedented precision at the Pierre Auger Observatory.
We report an update of the all-sky flux of cosmic rays above 3 x 10 [sup] 17 eV obtained by combining four
independent data sets. These measurements are based on data
from the surface detector arrays (divided into two sets according to the shower zenith angle), from a nested, denser,
detector array, and hybrid events measured simultaneously with
both the fluorescence detector and the surface detector array.
The spectral features are presented in detail and the
systematic uncertainties are addressed. The huge amount of data
collected to date, with a total exposure exceeding
50,000 km2 sr yr, together with the wide range of sky observed
(in declination from -90[deg] to 45[deg]) also allow us to
measure the energy spectrum from different regions of the sky.
We present the results of the search for a dependence of the
measured flux on the declination of the incoming directions.
Keywords: ultra-high energy cosmic rays
energy spectrum
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 6653; Downloads: 228
Full text (755,08 KB) |
