The atmospheric scattering of light has a significant influence on the results of optical observations of air showers. It causes attenuation of direct light from the shower, but also contributes a ...delayed signal to the observed light. The scattering of light therefore should be accounted for, both in simulations of air shower detection and reconstruction of observed events. In this work a Monte Carlo simulation of multiple scattering of light has been used to determine the contribution of the scattered light in observations of a point source of light. Results of the simulations and a parameterization of the angular distribution of the scattered light contribution to the observed signal (the point spread function) are presented.
•Analysis of atmospheric scattering of light from an isotropic point source.•Different geometries and atmospheric conditions were investigated.•A parameterization of scattered light distribution has been developed.•The parameterization allows one to easily account for the light scattering in air.•The results will be useful in analyses of observations of extensive air shower.
The identification of primary photons or specifying stringent limits on the photon flux is of major importance for understanding the origin of ultra-high energy (UHE) cosmic rays. UHE photons can ...initiate particle cascades in the geomagnetic field, which leads to significant changes in the subsequent atmospheric shower development. We present a Monte Carlo program allowing detailed studies of conversion and cascading of UHE photons in the geomagnetic field. The program named PRESHOWER can be used both as an independent tool or together with a shower simulation code. With the stand-alone version of the code it is possible to investigate various properties of the particle cascade induced by UHE photons interacting in the Earth's magnetic field before entering the Earth's atmosphere. Combining this program with an extensive air shower simulation code such as CORSIKA offers the possibility of investigating signatures of photon-initiated showers. In particular, features can be studied that help to discern such showers from the ones induced by hadrons. As an illustration, calculations for the conditions of the southern part of the Pierre Auger Observatory are presented.
Title of program:PRESHOWER 1.0
Catalogue identifier:ADWG
Program summary URL:
http://cpc.cs.qub.ac.uk/summaries/ADWG
Program obtainable: CPC Program Library, Quen's University of Belfast, N. Ireland
Computer on which the program has been thoroughly tested:Intel-Pentium based PC
Operating system:Linux, DEC-Unix
Programming language used:C, FORTRAN 77
Memory required to execute with typical data:<100 kB
No. of bits in a word:32
Has the code been vectorized?:no
Number of lines in distributed program, including test data, etc.:2567
Number of bytes in distributed program, including test data, etc.:25 690
Distribution format:tar.gz
Other procedures used in PRESHOWER
:IGRF N.A. Tsyganenko, National Space Science Data Center, NASA GSFC, Greenbelt, MD 20771, USA,
http://nssdc.gsfc.nasa.gov/space/model/magnetos/data-based/geopack.html, bessik, ran2 Numerical Recipes,
http://www.nr.com.
Nature of the physical problem:Simulation of a cascade of particles initiated by UHE photon passing through the geomagnetic field above the Earth's atmosphere.
Method of solution: The primary photon is tracked until its conversion into
e
+
e
−
pair or until it reaches the upper atmosphere. If conversion occurred each individual particle in the resultant preshower is checked for either bremsstrahlung radiation (electrons) or secondary gamma conversion (photons). The procedure ends at the top of atmosphere and the shower particle data are saved.
Restrictions on the complexity of the problem: Gamma conversion into particles other than electron pair has not been taken into account.
Typical running time: 100 preshower events with primary energy
10
20
eV
require a 800 MHz CPU time of about 50 min, with
10
21
eV
the simulation time for 100 events grows up to 500 min.
Atmospheric scattering of light emitted by an air shower not only attenuates direct fluorescence light from the shower, but also contributes to the observed shower light. So far only direct and ...singly scattered Cherenkov photons have been taken into account in routine analyses of the observed optical image of air showers. In this paper a Monte Carlo method of evaluating the contribution of multiply scattered light to the optical air shower image is presented, as well as results of simulations and a parameterization of scattered light contribution to measured shower signal.
The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary ...was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV-EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincident with the source were detected within 500 s around the merger time. Additionally, no MeV neutrino burst signal was detected coincident with the merger. We further carried out an extended search in the direction of the source for high-energy neutrinos within the 14 day period following the merger, but found no evidence of emission. We used these results to probe dissipation mechanisms in relativistic outflows driven by the binary neutron star merger. The non-detection is consistent with model predictions of short GRBs observed at a large off-axis angle.
Abstract
A promising energy range to look for angular correlations between cosmic rays of extragalactic origin and their sources is at the highest energies, above a few tens of EeV (1 EeV ≡ 10
18
...eV). Despite the flux of these particles being extremely low, the area of ∼3000 km
2
covered at the Pierre Auger Observatory, and the 17 yr data-taking period of the
Phase
1
of its operations, have enabled us to measure the arrival directions of more than 2600 ultra-high-energy cosmic rays above 32 EeV. We publish this data set, the largest available at such energies from an integrated exposure of 122,000 km
2
sr yr, and search it for anisotropies over the 3.4
π
steradians covered with the Observatory. Evidence for a deviation in excess of isotropy at intermediate angular scales, with ∼15° Gaussian spread or ∼25° top-hat radius, is obtained at the 4
σ
significance level for cosmic-ray energies above ∼40 EeV.
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is ...observed, confirming the presence of the so-called
second-knee
feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
The longitudinal profile of the most energetic cosmic-ray air shower measured so far, the event recorded by the Fly's Eye detector with a reconstructed primary energy of about 3.2
×
10
20 eV, is ...compared to simulated shower profiles. The calculations are performed with the CORSIKA code and include primary photons and different hadron primaries. For primary photons, preshower formation in the geomagnetic field is additionally treated in detail. For primary hadrons, the hadronic interaction models QGSJET 01 and SIBYLL 2.1 have been employed. The predicted longitudinal profiles are compared to the observation. A method for testing the hypothesis of a specific primary particle type against the measured profile is described which naturally takes shower fluctuations into account. The Fly's Eye event is compatible with any assumption of a hadron primary between proton and iron nuclei in both interaction models, although differences between QGSJET 01 and SIBYLL 2.1 in the predicted profiles of lighter nuclei exist. The primary photon profiles differ from the data on a level of ≃1.5
σ. Although not favoured by the observation, the primary photon hypothesis can not be rejected for this particular event.
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