The absolute calibration of the fluorescence detector telescopes of the Pierre Auger Observatory is an important element for correctly determining the energy of primary cosmic rays producing ...extensive air showers in the atmosphere. In this contribution we show that signals generated by stars traversing the field of view of the fluorescence detectors can effectively be used as a tool to verify their absolute calibration without requiring any dedicated external hardware device. After describing the details of the procedure we report on the preliminary results obtained by the analysis of signals from reference stars as observed by the fluorescence detector telescopes.
The radio emission from extensive air showers is measured with the LOFAR radio telescope and the Auger Engineering Radio array AERA at the Pierre Auger observatory. The properties of cosmic rays, ...such as direction, energy and particle type are derived from the radio measurements. Recent results and perspectives for the future are discussed.
Radio stations of the Auger Engineering Radio Array (AERA) investigates radio signals from coherent emissions due to geomagnetic radiation and charge excess processes. The frequency band is limited ...to 30–80 MHz. This range is highly contaminated by human-made RFI. In order to improve the signal to noise ratio, RFI filters have to be used to suppress this contamination.
The LMS filter proposed for the RFI suppression should use correct learning factor, crucial for a stability of the filter, which could be determined by eigenvalues of the auto-correlation matrix built for ADC samples.
A detailed analysis of almost one million of AERA events confirms that eigenvalues of real cosmic events taken from the AERA database fully allow their use in the LMS filters, with learning factors optimal for the most efficient RFI suppression.
This type of the filter can be used in other radio cosmic ray experiments e.g. the Giant Radio Array for Neutrino Detection (GRAND).
The surface detector array (SD) of the Pierre Auger Observatory is sensitive to neutrinos at energies in the 100 PeV to 100 EeV range. This sensitivity, together with its large acceptance, makes it a ...complementary detector to other neutrino telescopes, which have their peak sensitivities at lower energies. The neutrino-induced air showers that the SD of the Pierre Auger Observatory is sensitive to can be divided into those induced by interactions of neutrinos of any flavor deep in the atmosphere, and those induced by charged-current interactions of tau neutrinos in the Earth's crust. Both of these types can be efficiently distinguished from cosmic ray-induced air showers, provided that their zenith angles are larger than 60∘. As no neutrino candidates were found in the performed searches, we present limits on the diffuse all-flavor neutrino flux. Using these limits, we obtained constraints on cosmic-ray and neutrino production models. In the light of the recent observations of gravitational waves (GW), we also present the follow-up of LIGO/Virgo GW events. These include binary black hole merger events and also GW170817, the only binary neutron star merger ever observed directly.
We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5
×
10
17
eV with the surface detector array of the Pierre Auger Observatory, reporting on both the ...phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99%
C.
L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.
► The hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector has been determined. ► The hybrid detection mode combines the ...information from SD and FD systems reducing reconstruction uncertainties. ► Detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. ► A set of quality criteria has been developed in order to have exposure estimate as free as possible of systematics. The effect of the cuts has been cross-checked by comparing the data and Monte Carlo distributions.
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The “hybrid” detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction.
We are presenting a new approach to a filtering of radio frequency interference (RFI) in the Auger Engineering Radio Array (AERA), which studies the electromagnetic part of the extensive air showers. ...Radio stations can observe radio signals caused by coherent emissions due to geomagnetic radiation and charge excess processes. AERA observes the frequency band from 30 to 80 MHz. This range is highly contaminated by human-made RFI. In order to improve the signal to noise ratio RFI filters are used in AERA to suppress this contamination. The filter has already been tested with real AERA radio stations in the Argentinean Pampas with very successful results. The linear equations were solved either in the virtual soft-core NIOS® processor (implemented in the FPGA chip as a net of logic elements) or in the external Voipac PXA270M ARM processor. The NIOS® processor is relatively slow (50 MHz internal clock), and the calculations performed in an external processor consume a significant amount of time for data exchange between the FPGA and the processor. Tests showed very good efficiency of the RFI suppression for stationary (long-term) contaminations. However, we observed short-time contaminations, which could not be suppressed either by the IIR-notch filter or by the FIR filter based on the linear predictions. For the LP FIR filter, the refresh time of the filter coefficients was too long and the filter did not keep up with the changes in the contamination structure, mainly due to a long calculation time in a slow processors. We propose to use the Cyclone® V SE chip with an embedded micro-controller operating with a 925 MHz internal clock to significantly reduce the refreshment time of the FIR coefficients. First results in the laboratory are very promising.
► Analysis of data recorded at the Pierre Auger Observatory. ► We search for groups of aligned events which exhibit a correlation between arrival direction and the inverse of the energy. ► We ...describe the largest multiplets found. ► There is no statistically significant evidence for the presence of multiplets arising from magnetic deflections.
We present the results of an analysis of data recorded at the Pierre Auger Observatory in which we search for groups of directionally-aligned events (or ‘multiplets’) which exhibit a correlation between arrival direction and the inverse of the energy. These signatures are expected from sets of events coming from the same source after having been deflected by intervening coherent magnetic fields. The observation of several events from the same source would open the possibility to accurately reconstruct the position of the source and also measure the integral of the component of the magnetic field orthogonal to the trajectory of the cosmic rays. We describe the largest multiplets found and compute the probability that they appeared by chance from an isotropic distribution. We find no statistically significant evidence for the presence of multiplets arising from magnetic deflections in the present data.
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