Author: Moritz MünchmeyerPublisher:
ISBN:
Category :
Languages : en
Pages : 128
Book Description
Large-scale Anisotropies in the High Energy Cosmic Ray Sky
Author: Moritz MünchmeyerCoverage and large scale anisotropies estimation methods for the Pierre Auger Observatory
Author: J. Ch HamiltonPublisher:
ISBN:
Category :
Languages : en
Pages : 4
Book Description
When searching for anisotropies in the arrival directions of Ultra High Energy Cosmic Rays, one must estimate the number of events expected in each direction of the sky in the case of a perfect isotropy. We present in this article a new method, developed for the Auger Observatory, based on a smooth estimate of the zenith angle distribution obtained from the data itself (which is essentially unchanged in the case of the presence of a large scale anisotropy pattern). We also study the sensitivity of several methods to detect large-scale anisotropies in the cosmic ray arrival direction distribution : Rayleigh analysis, dipole fitting and angular power spectrum estimation.
Full - Sky Search for Ultrahigh - Energy Cosmic Ray Anisotropies
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Using data from the SUGAR and the AGASA experiments taken during a 10 yr period with nearly uniform exposure to the entire sky, we search for anisotropy patterns in the arrival directions of cosmic rays with energies> 10{sup 19.6} eV. We determine the angular power spectrum from an expansion in spherical harmonics for modes out to l = 5. Based on available statistics, we find no significant deviation from isotropy. We compare the rather modest results which can be extracted from existing data samples with the results that should be forthcoming as new full-sky observatories begin operation.
First Hints of Large Scale Structures in the Ultrahigh Energy Sky?.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 4
Book Description
The result of the recent publication [1] of a broad maximum around 25 degrees in the two-point autocorrelation function of ultra-high energy cosmic ray arrival directions has been intriguingly interpreted as the first imprint of the large scale structures (LSS) of baryonic matter in the near universe. We analyze this suggestion in light of the clustering properties expected from the PSCz astronomical catalogue of LSS. The chance probability of the signal is consistent within 2 [sigma] with the predictions based on the catalogue. No evidence for a significant cross-correlation of the observed events with known overdensities in the LSS is found, which may be due to the role of the galactic and extragalactic magnetic fields, and is however consistent with the limited statistics. The larger statistics to be collected by the Pierre Auger Observatory is needed to answer definitely the question.
Methods for the Reconstruction of Large Scale Anisotropies of the Cosmic Ray Flux
Author: Sven OverSystematic Studies of Cosmic-ray Anisotropy and Energy Spectrum with IceCube and IceTop
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 128
Book Description
Anisotropy in the cosmic-ray arrival direction distribution has been well documented over a large energy range, but its origin remains largely a mystery. In the TeV to PeV energy range, the galactic magnetic field thoroughly scatters cosmic rays, but anisotropy at the part-per-mille level and smaller persists, potentially carrying information about nearby cosmic-ray accelerators and the galactic magnetic field. The IceCube Neutrino Observatory was the first detector to observe anisotropy at these energies in the Southern sky. This work uses 318 billion cosmic-ray induced muon events, collected between May 2009 and May 2015 from both the in-ice component of IceCube as well as the surface component, IceTop. The observed global anisotropy features large regions of relative excess and deficit, with amplitudes on the order of $10^{-3}$. While a decomposition of the arrival direction distribution into spherical harmonics shows that most of the power is contained in the low-multipole ($\ell \leq 4$) moments, higher-multipole components are found to be statistically significant down to an angular scale of less than $10^{\circ}$, approaching the angular resolution of the detector. Above 100\,TeV, a change in the topology of the arrival direction distribution is observed, and the anisotropy is characterized by a wide relative deficit whose amplitude increases with primary energy up to at least 5\,PeV, the highest energies currently accessible to IceCube with sufficient event statistics. No time dependence of the large- and small-scale structures is observed in the six-year period covered by this analysis within statistical and systematic uncertainties. Analysis of the energy spectrum and composition in the PeV energy range as a function of sky position is performed with IceTop data over a five-year period using a likelihood-based reconstruction. Both the energy spectrum and the composition distribution are found to be consistent with a single source population over declination bands. This work represents an early attempt at understanding the anisotropy through the study of the spectrum and composition. The high-statistics data set reveals more details on the properties of the anisotropy, potentially able to shed light on the various physical processes responsible for the complex angular structure and energy evolution.
Small Scale Anisotropies of UHECRs from Super-heavy Halo Dark Matter
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The decay of very heavy metastable relics of the Early Universe can produce ultra-high energy cosmic rays (UHECRs) in the halo of our own Galaxy. In this model, no Greisen-Zatsepin-Kuzmin cutoff is expected because of the short propagation distances. They show here that, as a consequence of the hierarchical build up of the halo, this scenario predicts the existence of small scale anisotropies in the arrival directions of UHECRs, in addition to a large scale anisotropy, known from previous studies. They also suggest some other observable consequences of this scenario which will be testable with upcoming experiments, as Auguer, EUSO and OWL.
Astrophysics at Ultra-high Energies
Author: Maurice Mandel ShapiroPublisher: World Scientific
ISBN: 9812790144
Category : Science
Languages : en
Pages : 239
Book Description
This book introduces young researchers to the exciting field of ultra-high energy astrophysics including charged particles, gamma rays and neutrinos. At ultra-high energy the radiation is produced by interactions of cosmic ray particles accelerated in explosive events such as supernovae or hypernovae, black holes or, possibly, the big bang. Through direct contact with senior scientists, now actively planning the next generation of experiments/models, the excitement and motivation for research at ultra-high energy was conveyed. The underpinning of these fields is a synthesis of knowledge and techniques from nuclear and particle physics, astronomy and cosmology. Informing the participants of this background, how it was derived, and the new challenges for the future are the major goal. Further, the course has helped to foster new astrophysical research and promoted contacts, which have resulted in new collaborations.
New Worlds In Astroparticle Physics - Proceedings Of The International Workshop
Author: Ana Maria MouraoPublisher: World Scientific
ISBN: 9814545139
Category :
Languages : en
Pages : 454
Book Description
The proceedings of the first meeting on “New Worlds in Astroparticle Physics” focus on the joint field of particle physics and astrophysics. This is a field widely open to both theory and experiment. Important questions of particle physics — from the role of the Higgs scalar to the deconfined QCD phase, the developments beyond the Standard Model and the subtle behavior of neutrinos — are discussed. The same is true for the relevant questions in astrophysics and cosmology — from the fluctuations in the photon background radiation to large scale structure formation, dark matter searches and the origin of cosmic rays at very high energies. The two viewpoints, from the small sizes or from the large scales, are convergent and reveal the same universe: the universe of astroparticle physics.
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