Extremely High Energy Cosmic Rays Research Articles

Search for ultra high-energy cosmic rays from radiogalaxy Virgo A

Active galactic nuclei (AGNs) are considered to be one of the most appropriate sources of ultra high energy cosmic rays (UHECRs, $E \gtrsim 10^{18} \mathrm{~eV}$). Radiogalaxy Virgo A (M87) in the centre of a cluster of galaxies Virgo Cluster (VC) can be a prominent source of UHECRs. We investigate the possible contribution of Virgo A and the VC to the flux of events with trans-GZK energies - extremely high energy cosmic rays (EHECRs) - from the recent Auger and Telescope Array (TA) data sets ($E > 52 \mathrm{~EeV}$ and $E > 57 \mathrm{~EeV}$, respectively). We simulate EHECR propagation from Virgo A and the VC taking into account their deflections in galactic (GMF) and extragalactic (EGMF) magnetic fields and show that there is no excess of EHECR arrival directions from images of Virgo A/VC at different EHECR rigidities. By means of event-by-event analysis we recover the extragalactic arrival directions of EHECR events detected by Auger and TA for representative set of nuclei H(p), He, N, Si, Fe, and find evidences of enhanced fluxes of N-Si-Fe EHECRs from the Local Filament and Hot/Cold Spot regions. The Local Filament with its enhanced magnetic field is an expected contributor to the UHECR flux as the closest to the Earth last scattering centre, whereas Hot/Cold Spot region is a part of a larger arc-like spot, possibly created by diffusively spreading jet of UHECRs, accelerated in the relativistic jet of Virgo A during a prominent nuclear outburst about 10 - 12 Myr ago.

Thin and thick cloud top height retrieval algorithm with the Infrared Camera and LIDAR of the JEM-EUSO Space Mission

The origin of cosmic rays have remained a mistery for more than a century. JEM-EUSO is a pioneer space-based telescope that will be located at the International Space Station (ISS) and its aim is to detect Ultra High Energy Cosmic Rays (UHECR) and Extremely High Energy Cosmic Rays (EHECR) by observing the atmosphere. Unlike ground-based telescopes, JEM-EUSO will observe from upwards, and therefore, for a properly UHECR reconstruction under cloudy conditions, a key element of JEM-EUSO is an Atmospheric Monitoring System (AMS). This AMS consists of a space qualified bi-spectral Infrared Camera, that will provide the cloud coverage and cloud top height in the JEM-EUSO Field of View (FoV) and a LIDAR, that will measure the atmospheric optical depth in the direction it has been shot. In this paper we will explain the effects of clouds for the determination of the UHECR arrival direction. Moreover, since the cloud top height retrieval is crucial to analyze the UHECR and EHECR events under cloudy conditions, the retrieval algorithm that fulfills the technical requierements of the Infrared Camera of JEM-EUSO to reconstruct the cloud top height is presently reported.

The Atmospheric Monitoring System of the JEM-EUSO space mission

An Atmospheric Monitoring System (AMS) is a mandatory and key device of a space-based mission which aims to detect Ultra-High Energy Cosmic Rays (UHECR) and Extremely-High Energy Cosmic Rays (EHECR) from Space. JEM-EUSO has a dedicated atmospheric monitoring system that plays a fundamental role in our understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. Our AMS consists of a very challenging space infrared camera and a LIDAR device, that are being fully designed with space qualification to fulfil the scientific requirements of this space mission. The AMS will provide information of the cloud cover in the FoV of JEM-EUSO, as well as measurements of the cloud top altitudes with an accuracy of 500 m and the optical depth profile of the atmosphere transmittance in the direction of each air shower with an accuracy of 0.15 degree and a resolution of 500 m. This will ensure that the energy of the primary UHECR and the depth of maximum development of the EAS ( Extensive Air Shower) are measured with an accuracy better than 30\% primary energy and 120 $g/cm^2$ depth of maximum development for EAS occurring either in clear sky or with the EAS depth of maximum development above optically thick cloud layers. Moreover a very novel radiometric retrieval technique considering the LIDAR shots as calibration points, that seems to be the most promising retrieval algorithm is under development to infer the Cloud Top Height (CTH) of all kind of clouds, thick and thin clouds in the FoV of the JEM-EUSO space telescope.

JEM-EUSO mission on the ISS with the aim of performing particle astronomy

The Extreme Universe Space Observatory (EUSO) is a science mission to investigate the nature and origin of Extremely-High-Energy Cosmic Rays (EHECRs) with primary energy(E 0 ) > 7 × 10 19 eV . It will be installed in the Japanese Experiment Module (JEM) on the International Space Station (ISS). This mission is aimed to perform charged-particle astronomy in this energy region with large statistics of EHECRs (>1000 events above 7 × 10 19 eV ) in 5 years observation. The JEM-EUSO telescope has a Field of View(FoV) of 60 ° × 48 ° and a cumulative exposure of > 4 × 10 5 km 2 ⋅ sr ⋅ yr . It consists of high-transmittance Fresnel lenses (a side-cut shape with a 2.65 m major axis), a cluster of multi-anode photomultipliers(MAPMT) as a photo-sensitive detector at the focal surface and suitable electronics. JEM-EUSO has been selected as one of the mission candidates of the second phase utilization of JEM expected in early 2010s, by the Japan Aerospace eXploration Agency(JAXA).

The JEM-EUSO mission

JEM-EUSO is a space science mission to explore the extreme energies and physics of the Universe. Its instrument will watch the darkside of the earth and will detect UV photons emitted from the extensive air shower caused by an ultra-high energy cosmic ray (UHECR above 1018 eV), or an extremely high energy cosmic ray (EHECR) particle (e.g. above about 1020 eV). Such a high-rigidity particle as the latter arrives almost in a straight line from its origin through the magnetic fields of our Milky Way Galaxy and is expected to allow us to trace the source location by its arrival direction. This can open the door to new astronomy with charged particles. In its 5 years of operation including the tilted mode, Extreme Universe Space Observatory an Japanese Experiment Module (JEM-EUSO) will detect at least 1000 events with E>7×1019 eV with the Greisen–Zatsepin–Ku'zmin (GZK) suppression spectrum. It can determine the energy spectrum and source locations of GZK to super-GZK regions with a statistical accuracy of several percent. JEM-EUSO is planned to be deployed by H2 transfer vehicle (HTV) and will be attached to the Japanese Experiment Module/ Exposure Facility (JEM/EF) of International Space Station. JAXA has selected JEM-EUSO as one of the mission candidates of the second phase utilization of JEM/EF for launch in the early-to-mid 2010s.

JEM EUSO mission on the International Space Station

The Extreme-Universe Space Observatory (EUSO) on Japanese Experiment Module (JEM) is a mission on ISS [1], led by Japan Aerospace Exploration Agency (JAXA) to investigate the nature and origin of extremely-high-energy cosmic rays (EHECRs). This is the sole window on the extreme-energy universe. JAXA has selected JEM-EUSO for study as one of two international mission candidates for installation on the JEM Exposure Facility by 2013. JEM-EUSO (hereafter, EUSO) is designated to pioneer measurements of EHECR-induced extensive air showers (EAS) from space. As the detector, it uses the whole earth, observing from the International Space Station (ISS) where a remote sensor is located. The signal is fluorescent and Cherenkov light from the Extensive Air Showers (EAS).

Observation of Extremely High Energy Cosmic Rays by the Telescope Array

The existence of extremely high energy cosmic rays (EHECRs) with energy above 10 20 eV have been reported by AGASA and other air shower experiments. High energy astronomical objects such as the AGN and GRB are natural candidates as the origin, but most of them are distant and no relevant candidate were found in the horizon set by the interaction of EHECRs with the cosmic microwave background (CMB). We review the experimental status of EHECR and introduce a new experiment, Telescope Array, aiming at unveiling a mysterious origin of the EHECR.

COSMIC RAYS AT THE HIGHEST ENERGIES — FIRST DATA FROM THE PIERRE AUGER OBSERVATORY

The southern Pierre Auger Observatory, presently under construction in Malargüe, Argentina, is nearing completion. The instrument is designed to measure extensive air-showers with energies ranging from 1018-1020 eV and beyond. It combines two complementary observation techniques; the detection of particles at ground and the coincident observation of associated fluorescence light generated in the atmosphere above the ground. This is being realized by employing an array of 1600 water Cherenkov detectors, distributed over an area of 3000 km2, and operating 24 wide-angle Schmidt telescopes, positioned at four sites at the border of the ground array. The Observatory will reach its full size only in 2007 but data are routinely recorded already and have started to provide relevant science results. This talk will focus on the detector characterizations and presents first results on the arrival direction of extremely-high energy cosmic rays, their energy spectrum, and on the upper limit of the photon fraction.

The Highest Energy Cosmic Rays, A Review and Prospects

The existence of extremely high energy cosmic rays (EHECRs) with energy above 1020eV have been reported by several air shower experiments. The sources of these cosmic rays were considered to be extra-galactic. Relevant high energy astrophysical sources were searched in the arrival direction of these cosmic rays but no appropriate candidates were found. The origin of EHECRs stays unexplained. We review the present status of EHECR studies and introduce several new experiments aiming to unveil its mysterious origin.

Telescope Array Project for Extremely High Energy Cosmic Rays

The existence of extremely high energy cosmic rays (EHECRs) with energies exceeding 10 2 0 eV has been reported by the AGASA experiment. These cosmic rays may be produced in the active astronomical object in the outer galaxy and propagated a long distance toward the Earth. Such high energy 'stars have been searched in the arrival direction of these events but no clear candidates were found. A new experiment, Telescope Array (TA), is planned to unveil the enigmatic origin of the EHECRs. The physics motivation of TA is reviewed and its present status is reported.

Constraints on the extremely high-energy cosmic ray accelerators from classical electrodynamics

We formulate the general requirements, set by classical electrodynamics, on the sources of extremely high-energy cosmic rays (EHECRs). It is shown that the parameters of EHECR accelerators are strongly limited not only by the particle confinement in large-scale magnetic fields or by the difference in electric potentials (generalized Hillas criterion) but also by the synchrotron radiation, the electro-bremsstrahlung, or the curvature radiation of accelerated particles. Optimization of these requirements in terms of an accelerator's size and magnetic field strength results in the ultimate lower limit to the overall source energy budget, which scales as the fifth power of attainable particle energy. Hard \ensuremath{\gamma} rays accompanying generation of EHECRs can be used to probe potential acceleration sites. We apply the results to several populations of astrophysical objects---potential EHECR sources---and discuss their ability to accelerate protons to ${10}^{20} \mathrm{eV}$ and beyond. The possibility of gain from ultrarelativistic bulk flows is addressed, with active galactic nuclei and gamma-ray bursts being the examples.

Development of electromagnetic cascading in the Sun's magnetic field

The study of particle cascading initiated by Extremely High Energy (EHE) photons in the Sun's magnetic field offers us an opportunity to study some processes of astrophysical importance in space. This opportunity has beenparticularly useful in investigating the photon content in the EHE cosmic ray spectrum. The processes of magnetic pair creation and photon splitting are the basic mechanisms taken into account in our Monte Carlo simulation code. Such processes have been simulated for primary photons in the magnetic field near the Sun to study the characteristics of the cascading of these extraordinary showers. Upon simulation, such cascading particles produced by primary photons with an energy ≥10 1 9 eV could be detected on the Earth's surface within a solid angle of 6.12 x 10 - 4 sr from the Sun's position. The characteristics of cascading initiated by photons in such a strong magnetic field near the Sun are discussed.

Cluster analysis of extremely high energy cosmic rays in the northern sky

The arrival directions of extremely high energy cosmic rays (EHECR) above 4×10 19 eV, observed by four surface array experiments in the northern hemisphere, are examined for coincidences from similar directions in the sky. The total number of cosmic rays is 92. A significant number of double coincidences (doublet) and triple coincidences (triplet) is observed on the supergalactic plane within the experimental angular resolution. The chance probability of such multiplets from a uniform distribution is less than 1% if we consider a restricted region within ±10° of the supergalactic plane. Though there is still a possibility of chance coincidence, the present results on small angle clustering along the supergalactic plane may be important in interpreting EHECR enigma. An independent set of data is required to check our claims.

Telescope Array Project for Extremely High Energy Cosmic Rays

Telescope Array Project for Extremely High Energy Cosmic Rays

Cosmic Topological Defects, Highest Energy Cosmic Rays, and the Baryon Asymmetry of the Universe

It is pointed out that the observed extremely high energy cosmic rays (EHECR) above ${10}^{11}\mathrm{GeV}$ and the observed baryon asymmetry of the Universe (BAU) may have a common origin in baryon number violating decays of supermassive $X$ particles released from cosmic topological defects (TDs) such as cosmic strings and monopoles. The $X$ particles produced by TDs in the recent epochs produce the EHECR, while the BAU is created by $X$ particles released from TDs mainly in the very early Universe. In this scenario the EHECR is predicted to contain baryons as well as antibaryons with a small asymmetry between the two.

Extremely High Energy Neutrinos and Their Detection

We discuss in some detail the production of extremely high energy (EHE) neutrinos with energies above 1018 eV. The most certain process for producing such neutrinos results from photopion pro- duction by EHE cosmic rays in the cosmic background photon -eld. However, using assumptions for the EHE cosmic-ray source evolution that are consistent with results from the deep QSO survey in the radio and X-ray range, the resultant Nux of neutrinos from this process is not strong enough for plaus- ible detection. A measurable Nux of EHE neutrinos may be present, however, if the highest energy cosmic rays that have recently been detected well beyond 1020 eV are the result of the annihilation of topological defects which formed in the early universe. Neutrinos resulting from such decays reach ener- gies of the grand uni-ed theory scale, and collisions of superhigh-energy neutrinos with the cosmic back- ground neutrinos initiate neutrino cascading, which enhances the EHE neutrino Nux at Earth. We have calculated the neutrino Nux including this cascading e†ect for either massless or massive neutrinos, and we -nd that these Nuxes are conceivably detectable by air Nuorescence detectors now in development. The neutrino-induced showers would be recognized by their starting deep in the atmosphere. We evalu- ate the feasibility of detecting EHE neutrinos this way using air Nuorescence air shower detectors and derive the expected event rate. Other processes for producing deeply penetrating air showers constitute a negligible background. Subject headings: cosmic microwave background E cosmic rays E cosmic strings E early universe E elementary particles E instrumentation: detectors

Possible Clustering of the Most Energetic Cosmic Rays within a Limited Space Angle Observed by the Akeno Giant Air Shower Array.

Accumulated data of the Akeno Giant Air Shower Array (AGASA) indicate that arrival directions of a significant fraction of extremely high energy cosmic rays (EHECR) are uniformly distributed over the observable sky. However, three pairs of showers with angular separation of less than 2.5\ifmmode^\circ\else\textdegree\fi{} within the pair are observed among the 36 events above 40 EeV ( $4\ifmmode\times\else\texttimes\fi{}{10}^{19}\mathrm{eV}$), corresponding to a chance probability of 2.9% from uniform distribution. It should be noted that two pairs of them are observed to be within 2.0\ifmmode^\circ\else\textdegree\fi{} of the supergalactic plane.