Astrophysics
Taking into account the Pierre Auger Observatory limits on the photon fraction among the highest energy cosmic rays, we show that the models based on the decay of super-heavy dark matter in the halo of our Galaxy are essentially excluded…
We present updated results for anisotropy searches in the direction of the Galactic Center (GC) at energies in the ranges: 0.1<E<1 EeV and 1<E<10 EeV. We use data from the Pierre Auger Observatory up to March, 2007. Present analyzes are…
More than two years of fluorescence detector data collected in coincidence with at least one station of the surface detector array (``hybrid data'') are used to measure the flux and energy spectrum of cosmic rays above about 10$^{18}$ eV.…
We use more than two years of data from the Pierre Auger Observatory to search for anisotropies on large scales in different energy windows. We account for various systematics in the acceptance, in particular due to the array growth and…
At the southern site of the Pierre Auger Observatory, which is close to completion, an exposure that significantly exceeds the largest forerunner experiments has already been accumulated. We report a measurement of the cosmic ray energy…
The Pierre Auger Observatory allows the measurement of both longitudinal profiles and lateral particle distributions of high-energy showers. The former trace the overall shower development, mainly of the electromagnetic component close to…
If clustering of the arrival directions of ultra high energy cosmic rays is discovered, this would provide important information about their origin, composition, and the galactic and extragalactic magnetic fields. We present here the…
A wide range of atmospheric monitoring instruments is employed at the Pierre Auger Observatory: two laser facilities, elastic lidar stations, aerosol phase function monitors, a horizontal attenuation monitor, star monitors, weather…
Several analyses of the data collected by other experiments have found an excess of cosmic rays in correlation with subclasses of BL Lacs. Data from the Pierre Auger Observatory do not support previously reported excesses. The number of…
FRAM - F/(Ph)otometric Robotic Atmospheric Monitor is the latest addition to the atmospheric monitoring instruments of the Pierre Auger Observatory. An optical telescope equipped with CCD camera and photometer, it automatically observes a…
With the Pierre Auger Observatory we have the capability of detecting ultra-high energy neutrinos by searching for very inclined showers with a significant electromagnetic component. In this work we discuss the discrimination power of the…
A key step towards the understanding of the origin of ultra-high energy cosmic rays is their mass composition. Primary photons and neutrinos produce markedly different showers from nuclei, while showers of different nuclear species are not…
The Pierre Auger Observatory has been collecting data in a stable manner since January 2004. We present here a study of the cosmic ray composition using events recorded in hybrid mode during the first years of data taking. These are air…
The rate of events measured with the surface detector of the Pierre Auger Observatory is found to be modulated by the weather conditions. This effect is due to the increasing amount of matter traversed by the shower as the ground pressure…
The building block of the surface detector of the Pierre Auger Observatory is a water Cherenkov tank. The response to shower particles is simulated using a dedicated program based on GEANT4. To check the simulation chain, we compare the…
A key feature of the Pierre Auger Observatory is its hybrid design, in which ultra high energy cosmic rays are detected simultaneously by fluorescence telescopes and a ground array. The two techniques see air showers in complementary ways,…
The data collected by the Pierre Auger Observatory are analyzed to search for coincidences between the arrival directions of high-energy cosmic rays and the positions in the sky of astrophysical transients. Special attention is directed…
The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber (XeTPC) to search for dark matter weakly interacting massive particles (WIMPs). The detector measures simultaneously the…
All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources…
We searched for very high energy (VHE) gamma-ray emission from the supernova remnant Cassiopeia A. The shell-type supernova remnant Cassiopeia A was observed with the 17 meter MAGIC telescope between July 2006 and January 2007 for a total…