scholarly journals COSMIC RAYS IN GALAXY CLUSTERS AND THEIR NONTHERMAL EMISSION

2014 ◽  
Vol 23 (04) ◽  
pp. 1430007 ◽  
Author(s):  
GIANFRANCO BRUNETTI ◽  
THOMAS W. JONES
Keyword(s):  
Cosmic Rays ◽  
Galaxy Clusters ◽  
High Energy ◽  
Synchrotron Emission ◽  
High Energies ◽  
Electrical Conductivities ◽  
Nonthermal Emission ◽  
Near Future ◽  
Nonthermal Emissions ◽  
Relativistic Particles

Radio observations prove the existence of relativistic particles and magnetic field associated with the intra-cluster-medium (ICM) through the presence of extended synchrotron emission in the form of radio halos and peripheral relics. This observational evidence has fundamental implications on the physics of the ICM. Nonthermal components in galaxy clusters are indeed unique probes of very energetic processes operating within clusters that drain gravitational and electromagnetic energy into cosmic rays (CRs) and magnetic fields. These components strongly affect the (micro-)physical properties of the ICM, including viscosity and electrical conductivities, and have also potential consequences on the evolution of clusters themselves. The nature and properties of CRs in galaxy clusters, including the origin of the observed radio emission on cluster-scales, have triggered an active theoretical debate in the last decade. Only recently we can start addressing some of the most important questions in this field, thanks to recent observational advances, both in the radio and at high energies. The properties of CRs and of cluster nonthermal emissions depend on the dynamical state of the ICM, the efficiency of particle acceleration mechanisms in the ICM and on the dynamics of these CRs. In this paper, we discuss in some detail the acceleration and transport of CRs in galaxy clusters and the most relevant observational milestones that have provided important steps on our understanding of this physics. Finally, looking forward to the possibilities from new generations of observational tools, we focus on what appear to be the most important prospects for the near future from radio and high-energy observations.

scholarly journals The Nature of the Galactic Center Arc

1996 ◽  
Vol 169 ◽  
pp. 263-269 ◽  
Author(s):  
E. Serabyn
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Galactic Center ◽  
Magnetic Energy ◽  
Linear Structure ◽  
High Energy ◽  
Molecular Gas ◽  
Synchrotron Emission ◽  
Interferometric Imaging ◽  
Relativistic Particles

Ever since the Galactic Center Arc was resolved into its component filaments a decade ago, it has been clear that its linear structure arises from the influence of a strong magnetic field. However, the origin and nature of the contributory phenomena have remained elusive. Since what is seen is synchrotron emission from relativistic particles, of prime interest is a knowledge of the acceleration mechanism involved. Interferometric imaging of the molecular gas in the vicinity of the Arc has now provided a tantalizing clue to the Arc's origin: molecular clumps coinciding with the endpoints of a number of the Arc's filaments point to these clumps as the source of the relativistic particles. This suggests that as dense molecular clumps course through the ambient magnetic field at the Galactic Center, magnetic energy is liberated in their leading layers via field reconnection, precipitating rapid acceleration of free charges to high energy.

REVIEW ON PRECISION MEASUREMENTS OF HIGH ENERGY HADRONS

2002 ◽  
Vol 17 (12n13) ◽  
pp. 1603-1612 ◽  
Author(s):  
J. CASAUS
Keyword(s):  
Cosmic Rays ◽  
Energy Range ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Precision Measurements ◽  
Propagation Models ◽  
The Status ◽  
Free Parameters ◽  
Near Future

Precise measurements of high energy hadrons have been performed either on balloon-borne or space-borne experiments. The status of the present measurements on H and He, heavier nuclei, isotopes and antiprotons is separately reported. Implications of precise measurements within the framework of models for production and propagation of galactic cosmic rays is discussed. Near future experiments are expected to improve in a significant manner the collected statistics and the energy range covered by present experiments. The results thus obtained will validate current propagation models and accurately constrain their free parameters.

scholarly journals Information Technologies on High-Energy Astrophysics: Cosmic Ray Anisotropy using HAWC Observatory

2019 ◽  
Vol 208 ◽  
pp. 03005
Author(s):  
Eduardo de la Fuente ◽  
Juan Carlos Díaz–Vélez ◽  
Paolo Desiati ◽  
Jose Luis García–Luna ◽  
Janet Torrealba ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
High Altitude ◽  
Information Technologies ◽  
Cherenkov Radiation ◽  
Cosmic Ray ◽  
High Energy ◽  
High Impact ◽  
High Energy Astrophysics ◽  
High Energies ◽  
Radiation Technique

The detection of astroparticles, specially at high energies (>100 GeV), requires special techniques and instruments (telescopes or observatories), for example, those that use the Water Cherenkov radiation technique. In this paper we show an example of how Information Technologies can be used to perform maps and produce high impact results. The latter case is illustrated in the summary of the generation of a high statistics map of cosmic rays at 10 TeV in the northern sky with data collected by the High Altitude Water Cherenkov (HAWC) observatory.

scholarly journals SPONTANEOUS VIOLATION OF LORENTZ INVARIANCE AND ULTRA-HIGH ENERGY COSMIC RAYS

2003 ◽  
Vol 12 (07) ◽  
pp. 1279-1287 ◽  
Author(s):  
J. W. MOFFAT
Keyword(s):  
Cosmic Rays ◽  
Lorentz Invariance ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
High Energy ◽  
Spontaneous Breaking ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
High Energies ◽  
Local Lorentz Invariance

We propose that local Lorentz invariance is spontaneously violated at high energies, due to a nonvanishing vacuum expectation value of a vector field ϕμ, as a possible explanation of the observation of ultra-high energy cosmic rays with an energy above the GZK cutoff. Certain consequences of spontaneous breaking of Lorentz invariance in cosmology are discussed.

scholarly journals Diffuse Cluster-Wide Radio Halos

2002 ◽  
Vol 12 ◽  
pp. 516-518
Author(s):  
Haida Liang
Keyword(s):  
Magnetic Fields ◽  
High Energy ◽  
Synchrotron Emission ◽  
Gas Distribution ◽  
Seed Particles ◽  
High Energy Tail ◽  
Relativistic Particles ◽  
Radio Halos

AbstractWe will discuss the properties and origins of halos and relics including estimates of the cluster magnetic fields, and present results for a few recently discovered halos and relics. The electrons in the suprathermal high energy tail of the thermal gas distribution are likely to provide the seed particles for acceleration through mergers and turbulences to relativistic energies. These relativistic particles are then responsible for the synchrotron emission of the halos.

scholarly journals Shock acceleration efficiency in radio relics

2020 ◽  
Vol 634 ◽  
pp. A64 ◽  
Author(s):  
A. Botteon ◽  
G. Brunetti ◽  
D. Ryu ◽  
S. Roh
Keyword(s):  
Cosmic Rays ◽  
Galaxy Clusters ◽  
Electron Acceleration ◽  
Shock Acceleration ◽  
X Rays ◽  
Radio Luminosity ◽  
Diffusive Shock Acceleration ◽  
Astrophysical Shocks ◽  
Energy Dissipated ◽  
Relativistic Particles

Context. Radio relics in galaxy clusters are giant diffuse synchrotron sources powered in cluster outskirts by merger shocks. Although the relic–shock connection has been consolidated in recent years by a number of observations, the details of the mechanisms leading to the formation of relativistic particles in this environment are still not well understood. Aims. The diffusive shock acceleration (DSA) theory is a commonly adopted scenario to explain the origin of cosmic rays at astrophysical shocks, including those in radio relics in galaxy clusters. However, in a few specific cases it has been shown that the energy dissipated by cluster shocks is not enough to reproduce the luminosity of the relics via DSA of thermal particles. Studies based on samples of radio relics are required to further address this limitation of the mechanism. Methods. In this paper, we focus on ten well-studied radio relics with underlying shocks observed in the X-rays and calculate the electron acceleration efficiency of these shocks that is necessary to reproduce the observed radio luminosity of the relics. Results. We find that in general the standard DSA cannot explain the origin of the relics if electrons are accelerated from the thermal pool with an efficiency significantly smaller than 10%. Our results show that other mechanisms, such as shock re-acceleration of supra-thermal seed electrons or a modification of standard DSA, are required to explain the formation of radio relics.

scholarly journals High-energy processes in starburst-driven winds

2020 ◽  
Vol 496 (2) ◽  
pp. 2474-2481 ◽  
Author(s):  
Ana L Müller ◽  
Gustavo E Romero ◽  
Markus Roth
Keyword(s):  
Cosmic Rays ◽  
Power Law ◽  
Large Scale ◽  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Energy Processes ◽  
Relativistic Particles

ABSTRACT Starburst galaxies generate large-scale winds powered by the activity in the star-forming regions located in the galactic discs. Fragmentation of the disc produced by the outbreak of the wind results in the formation of clouds. Bowshocks caused by the supersonic outflow appear around such clouds. In this paper, we discuss the acceleration of relativistic particles and the production of non-thermal radiation in such scenario. Cosmic rays accelerated at the bowshocks do not reach the highest energies, although the high-energy luminosity generated is significant. We show that up to ∼10 per cent of the gamma-ray emission in starbursts might come from these sources outside the galactic discs. Discrete X-ray sources with a power-law component are also expected.

scholarly journals Magnetic fields and cosmic rays in galaxy clusters and large scale structures

2008 ◽  
Vol 4 (S259) ◽  
pp. 519-528 ◽  
Author(s):  
Klaus Dolag ◽  
F. Stasyszyn ◽  
J. Donnert ◽  
R. Pakmor
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Numerical Simulations ◽  
Galaxy Clusters ◽  
Large Scale ◽  
High Energy ◽  
Transport Processes ◽  
Origin And Evolution ◽  
Large Scale Structures ◽  
High Energy Particles

AbstractIn galaxy clusters, non-thermal components such as magnetic field and high energy particles keep a record of the processes acting since early times till now. These components play key roles by controlling transport processes inside the cluster atmosphere and beyond and therefore have to be understood in detail by means of numerical simulations. The complexity of the intra cluster medium revealed by multi-frequency observations demonstrates that a variety of physical processes are in action and must be included properly to produce accurate and realistic models. Confronting the predictions of numerical simulations with observations allows us to validate different scenarios about origin and evolution of large scale magnetic fields and to investigate their role in transport and acceleration processes of cosmic rays.

scholarly journals High Energy Cosmic Rays from Young Neutron Stars

1987 ◽  
Vol 125 ◽  
pp. 554-554
Author(s):  
Shigeki Miyaji
Keyword(s):  
Chemical Composition ◽  
Cosmic Rays ◽  
Energy Range ◽  
Neutron Stars ◽  
Cosmic Ray ◽  
High Energy ◽  
Heavy Nuclei ◽  
Intensity Enhancement ◽  
High Energy Cosmic Rays ◽  
High Energies

Cosmic ray spectrum has an intensity enhancement at energy range 1014–16 eV/nuc. Recently Takahasi et al. (1986) called an attention to chemical composition there. Although the data still contain large uncertainties, they argued an overabundance of calcium at high energies (Ca/Fe ≥ 2 above 1014 eV/nucleus) and some enhancements of medium heavy nuclei (C ∼ Ar) instead of no anomalous p, He, and Fe abundances.

Sign in / Sign up

Export Citation Format

Share Document