To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic ... more To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic rays (UHECRs), it is important to confront data with simulated astrophysical scenarios. These scenarios should include detailed information on particle interactions and astrophysical environments. To achieve this goal one should make use of computational tools to simulate the propagation of these particles. For this reason the CRPropa framework was developed. It allows the propagation of UHECRs with energies 10 17 eV and secondary gamma rays and neutrinos. The newest version, CRPropa 3, reflects an efficient redesign of the code as well as several new features such as time dependent propagation in three dimensions, galactic magnetic field effects and improved treatment of interactions, among other enhancements.
To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic ... more To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic rays (UHECRs), it is important to confront data with simulated astrophysical scenarios. These scenarios should include detailed information on particle interactions and astrophysical environments. To achieve this goal one should make use of computational tools to simulate the propagation of these particles. For this reason the CRPropa framework was developed. It allows the propagation of UHECRs with energies 10 17 eV and secondary gamma rays and neutrinos. The newest version, CRPropa 3, reflects an efficient redesign of the code as well as several new features such as time dependent propagation in three dimensions, galactic magnetic field effects and improved treatment of interactions, among other enhancements.
The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra... more The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10 18 eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data.
The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra... more The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10 18 eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data.
In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects th... more In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects the propagation of ultrahigh energy heavy nuclei. We investigate first how the images of individual sources and of the supergalactic plane depend on the properties of the turbulent GMF. Then we present a quantitative study of the impact of the turbulent field on (de-) magnification of source fluxes, due to magnetic lensing effects. We also show that it is impossible to explain the Pierre Auger data assuming that all ultrahigh energy nuclei are coming from Cen A, even in the most favorable case of a strong, extended turbulent field in the Galactic halo.
In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects th... more In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects the propagation of ultrahigh energy heavy nuclei. We investigate first how the images of individual sources and of the supergalactic plane depend on the properties of the turbulent GMF. Then we present a quantitative study of the impact of the turbulent field on (de-) magnification of source fluxes, due to magnetic lensing effects. We also show that it is impossible to explain the Pierre Auger data assuming that all ultrahigh energy nuclei are coming from Cen A, even in the most favorable case of a strong, extended turbulent field in the Galactic halo.
, ger-teshima-M-abs1-he15-poster EUSO is a mission to explore the extreme universe by the probe o... more , ger-teshima-M-abs1-he15-poster EUSO is a mission to explore the extreme universe by the probe of Ultra High Energy Cosmic Rays (UHECRs) and UHE neutrinos [1]. EUSO monitors a gigantic volume of atmosphere from Space and measures showers induced by UHECRs and UHE neutrinos. Scientifically, it is important to measure the energy spectrum of UHECRs well beyond GZK energy with high statistics. EUSO ensures the observation of UHECRs up to 10 21 eV even in the case of GZK mechanism working [2-7], and gives us a clear picture of the existence / non-existence of the GZK effect and the behavior of the spectrum beyond GZK energy, which represents the contributions from nearby sources. The anisotropy study of UHECR arrival directions in a small scale angle above GZK energy may allow us to identify individual source, because of the limited propagation distance and the high rigidity of particles. If event clusters observed by AGASA are real, it is expected from Monte Carlo simulation that EUSO will see ~100 particles from individual brightest sources and will give us a good opportunity to test the relativity in high precision. The UHE neutrino is a unique channel to explore the universe much deeper than UHECRs. EUSO essentially can measure UHE neutrinos free from background proton showers. The number of GZK neutrino events in a EUSO three years' mission is expected to be only a few. Nevertheless, it is a definitely conceivable opportunity to begin UHE neutrino astrophysics at GZK energy.
New particle physics beyond the standard model is expected to play an important role in the early... more New particle physics beyond the standard model is expected to play an important role in the early universe. Some of the possible resulting processes such as decaying topological defects or massive, long-lived dark matter particles, can contribute to the cosmic and gamma-radiation observed today. This data thus constrains and probes early universe physics. In addition, such processes could give rise to a relic ultra-high energy neutrino flux that could be detected with future neutrino telescopes. We discuss recent results and future prospects in this field.
The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular... more The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular, the highest energy cosmic rays observed have macroscopic energies up to several 10 20 electron volts and thus provide a probe of physics and astrophysics at energies unattained in laboratory experiments. Theoretical explanations range from astrophysical acceleration of charged particles, to particle physics beyond the established standard model, and processes taking place at the earliest moments of our universe. Distinguishing between these scenarios requires detectors with effective areas in the 1000-square-kilometer range, which are now under construction or in the planning stage. Close connections with γ-ray and neutrino astrophysics add to the interdisciplinary character of this field.
Proceedings of the National Academy of Sciences, 1997
Recently, a possible clustering of a subset of observed ultra-high energy cosmic rays above ≃40 E... more Recently, a possible clustering of a subset of observed ultra-high energy cosmic rays above ≃40 EeV (4 × 10 19 eV) in pairs near the supergalactic plane was reported. We show that a confirmation of this effect would provide information on the origin and nature of these events and, in case of charged primaries, imply interesting constraints on the extragalactic magnetic field. Possible implications for the most common models of ultra-high energy cosmic ray production in the literature are discussed.
We consider a model in which massive stars form in a self-gravitating accretion disk around an ac... more We consider a model in which massive stars form in a self-gravitating accretion disk around an active galactic nucleus (AGN). These stars may evolve and collapse to form compact objects on a time scale shorter than the accretion time, thus producing an important family of sources for LISA. Assuming the compact object formation/inspiral rate is proportional to the steady-state gas accretion rate, we use the intrinsic hard X-ray AGN luminosity function to estimate expected event rates and signal strengths. We find that these sources will produce a continuous low-frequency (< ∼ 1 mHz) background detectable by LISA if more than ∼ 1% of the accreted matter is in the form of compact objects. For compact objects with masses > ∼ 10M⊙, the last stages of the inspiral events should be resolvable above a few mHz, with rates as high as a few hundred per year.
Monthly Notices of the Royal Astronomical Society, 2001
Annihilations of weakly interacting dark matter particles provide an important signature for the ... more Annihilations of weakly interacting dark matter particles provide an important signature for the possibility of indirect detection of dark matter in galaxy haloes. These self-annihilations can be greatly enhanced in the vicinity of a massive black hole. We show that the massive black hole present at the centre of our galaxy accretes dark matter particles, creating a region of very high particle density. Consequently the annihilation rate is considerably increased, with a large number of e 1 e 2 pairs being produced either directly or by successive decays of mesons. We evaluate the synchrotron emission (and self-absorption) associated with the propagation of these particles through the galactic magnetic field, and are able to constrain the allowed values of masses and cross sections of dark matter particles.
If ν µ or ν τ mix with ν e , neutrino oscillations and collisions in a supernova (SN) core allow ... more If ν µ or ν τ mix with ν e , neutrino oscillations and collisions in a supernova (SN) core allow these flavors effectively to participate in β equilibrium and thus to obtain a large chemical potential. If a sterile species mixes with ν e , these effects lead to an anomalous loss of energy and lepton number. We study flavor conversion in a SN core on the basis of a new kinetic equation which rigorously includes neutrino interference and degeneneracy effects. Our discussion serves as an example and illustration of the properties of this "non-abelian Boltzmann equation".
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a su... more 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.
To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic ... more To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic rays (UHECRs), it is important to confront data with simulated astrophysical scenarios. These scenarios should include detailed information on particle interactions and astrophysical environments. To achieve this goal one should make use of computational tools to simulate the propagation of these particles. For this reason the CRPropa framework was developed. It allows the propagation of UHECRs with energies 10 17 eV and secondary gamma rays and neutrinos. The newest version, CRPropa 3, reflects an efficient redesign of the code as well as several new features such as time dependent propagation in three dimensions, galactic magnetic field effects and improved treatment of interactions, among other enhancements.
To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic ... more To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic rays (UHECRs), it is important to confront data with simulated astrophysical scenarios. These scenarios should include detailed information on particle interactions and astrophysical environments. To achieve this goal one should make use of computational tools to simulate the propagation of these particles. For this reason the CRPropa framework was developed. It allows the propagation of UHECRs with energies 10 17 eV and secondary gamma rays and neutrinos. The newest version, CRPropa 3, reflects an efficient redesign of the code as well as several new features such as time dependent propagation in three dimensions, galactic magnetic field effects and improved treatment of interactions, among other enhancements.
The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra... more The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10 18 eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data.
The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra... more The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10 18 eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data.
In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects th... more In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects the propagation of ultrahigh energy heavy nuclei. We investigate first how the images of individual sources and of the supergalactic plane depend on the properties of the turbulent GMF. Then we present a quantitative study of the impact of the turbulent field on (de-) magnification of source fluxes, due to magnetic lensing effects. We also show that it is impossible to explain the Pierre Auger data assuming that all ultrahigh energy nuclei are coming from Cen A, even in the most favorable case of a strong, extended turbulent field in the Galactic halo.
In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects th... more In this work we study how the turbulent component of the Galactic magnetic field (GMF) affects the propagation of ultrahigh energy heavy nuclei. We investigate first how the images of individual sources and of the supergalactic plane depend on the properties of the turbulent GMF. Then we present a quantitative study of the impact of the turbulent field on (de-) magnification of source fluxes, due to magnetic lensing effects. We also show that it is impossible to explain the Pierre Auger data assuming that all ultrahigh energy nuclei are coming from Cen A, even in the most favorable case of a strong, extended turbulent field in the Galactic halo.
, ger-teshima-M-abs1-he15-poster EUSO is a mission to explore the extreme universe by the probe o... more , ger-teshima-M-abs1-he15-poster EUSO is a mission to explore the extreme universe by the probe of Ultra High Energy Cosmic Rays (UHECRs) and UHE neutrinos [1]. EUSO monitors a gigantic volume of atmosphere from Space and measures showers induced by UHECRs and UHE neutrinos. Scientifically, it is important to measure the energy spectrum of UHECRs well beyond GZK energy with high statistics. EUSO ensures the observation of UHECRs up to 10 21 eV even in the case of GZK mechanism working [2-7], and gives us a clear picture of the existence / non-existence of the GZK effect and the behavior of the spectrum beyond GZK energy, which represents the contributions from nearby sources. The anisotropy study of UHECR arrival directions in a small scale angle above GZK energy may allow us to identify individual source, because of the limited propagation distance and the high rigidity of particles. If event clusters observed by AGASA are real, it is expected from Monte Carlo simulation that EUSO will see ~100 particles from individual brightest sources and will give us a good opportunity to test the relativity in high precision. The UHE neutrino is a unique channel to explore the universe much deeper than UHECRs. EUSO essentially can measure UHE neutrinos free from background proton showers. The number of GZK neutrino events in a EUSO three years' mission is expected to be only a few. Nevertheless, it is a definitely conceivable opportunity to begin UHE neutrino astrophysics at GZK energy.
New particle physics beyond the standard model is expected to play an important role in the early... more New particle physics beyond the standard model is expected to play an important role in the early universe. Some of the possible resulting processes such as decaying topological defects or massive, long-lived dark matter particles, can contribute to the cosmic and gamma-radiation observed today. This data thus constrains and probes early universe physics. In addition, such processes could give rise to a relic ultra-high energy neutrino flux that could be detected with future neutrino telescopes. We discuss recent results and future prospects in this field.
The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular... more The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular, the highest energy cosmic rays observed have macroscopic energies up to several 10 20 electron volts and thus provide a probe of physics and astrophysics at energies unattained in laboratory experiments. Theoretical explanations range from astrophysical acceleration of charged particles, to particle physics beyond the established standard model, and processes taking place at the earliest moments of our universe. Distinguishing between these scenarios requires detectors with effective areas in the 1000-square-kilometer range, which are now under construction or in the planning stage. Close connections with γ-ray and neutrino astrophysics add to the interdisciplinary character of this field.
Proceedings of the National Academy of Sciences, 1997
Recently, a possible clustering of a subset of observed ultra-high energy cosmic rays above ≃40 E... more Recently, a possible clustering of a subset of observed ultra-high energy cosmic rays above ≃40 EeV (4 × 10 19 eV) in pairs near the supergalactic plane was reported. We show that a confirmation of this effect would provide information on the origin and nature of these events and, in case of charged primaries, imply interesting constraints on the extragalactic magnetic field. Possible implications for the most common models of ultra-high energy cosmic ray production in the literature are discussed.
We consider a model in which massive stars form in a self-gravitating accretion disk around an ac... more We consider a model in which massive stars form in a self-gravitating accretion disk around an active galactic nucleus (AGN). These stars may evolve and collapse to form compact objects on a time scale shorter than the accretion time, thus producing an important family of sources for LISA. Assuming the compact object formation/inspiral rate is proportional to the steady-state gas accretion rate, we use the intrinsic hard X-ray AGN luminosity function to estimate expected event rates and signal strengths. We find that these sources will produce a continuous low-frequency (< ∼ 1 mHz) background detectable by LISA if more than ∼ 1% of the accreted matter is in the form of compact objects. For compact objects with masses > ∼ 10M⊙, the last stages of the inspiral events should be resolvable above a few mHz, with rates as high as a few hundred per year.
Monthly Notices of the Royal Astronomical Society, 2001
Annihilations of weakly interacting dark matter particles provide an important signature for the ... more Annihilations of weakly interacting dark matter particles provide an important signature for the possibility of indirect detection of dark matter in galaxy haloes. These self-annihilations can be greatly enhanced in the vicinity of a massive black hole. We show that the massive black hole present at the centre of our galaxy accretes dark matter particles, creating a region of very high particle density. Consequently the annihilation rate is considerably increased, with a large number of e 1 e 2 pairs being produced either directly or by successive decays of mesons. We evaluate the synchrotron emission (and self-absorption) associated with the propagation of these particles through the galactic magnetic field, and are able to constrain the allowed values of masses and cross sections of dark matter particles.
If ν µ or ν τ mix with ν e , neutrino oscillations and collisions in a supernova (SN) core allow ... more If ν µ or ν τ mix with ν e , neutrino oscillations and collisions in a supernova (SN) core allow these flavors effectively to participate in β equilibrium and thus to obtain a large chemical potential. If a sterile species mixes with ν e , these effects lead to an anomalous loss of energy and lepton number. We study flavor conversion in a SN core on the basis of a new kinetic equation which rigorously includes neutrino interference and degeneneracy effects. Our discussion serves as an example and illustration of the properties of this "non-abelian Boltzmann equation".
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a su... more 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.
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Papers by G. Sigl