scholarly journals Structure formation cosmic rays: Identifying observational constraints

2005 ◽  
pp. 33-45 ◽  
Author(s):  
T. Prodanovic ◽  
B.D. Fields
Keyword(s):  
Cosmic Rays ◽  
Structure Formation ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Big Bang ◽  
Alpha Particles ◽  
Fusion Reactions ◽  
Rare Isotope ◽  
Halo Stars ◽  
History Of

Shocks that arise from baryonic in-fall and merger events during the structure formation are believed to be a source of cosmic rays. These "structure formation cosmic rays" (SFCRs) would essentially be primordial in composition, namely, mostly made of protons and alpha particles. However, very little is known about this population of cosmic rays. One way to test the level of its presence is to look at the products of hadronic reactions between SFCRs and the ISM. A perfect probe of these reactions would be Li. The rare isotope Li is produced only by cosmic rays, dominantly in ?? ? 6Li fusion reactions with the ISM helium. Consequently, this nuclide provides a unique diagnostic of the history of cosmic rays. Exactly because of this unique property is Li affected most by the presence of an additional cosmic ray population. In turn, this could have profound consequences for the Big-Bang nucleosynthesis: cosmic rays created during cosmic structure formation would lead to pre-Galactic Li production, which would act as a "contaminant" to the primordial 7Li content of metalpoor halo stars. Given the already existing problem of establishing the concordance between Li observed in halo stars and primordial 7Li as predicted by the WMAP, it is crucial to set limits to the level of this "contamination". However, the history of SFCRs is not very well known. Thus we propose a few model-independent ways of testing the SFCR species and their history, as well as the existing lithium problem: 1) we establish the connection between gamma-ray and Li production, which enables us to place constraints on the SFCR-made lithium by using the observed Extragalactic Gamma-Ray Background (EGRB); 2) we propose a new site for testing the primordial and SFCR-made lithium, namely, low-metalicity High-Velocity Clouds (HVCs), which retain the pre-Galactic composition without any significant depletion. Although using one method alone may not give us strong constraints, using them in concert will shed a new light on the SFCR population and possibly give some answers about the pressing lithium problem. .

scholarly journals Cosmic Ray Production of 6Li by Virialisation Shocks in the Early Milky Way

2004 ◽  
Vol 21 (2) ◽  
pp. 148-152 ◽  
Author(s):  
Takeru K. Suzuki ◽  
Susumu Inoue
Keyword(s):  
Cosmic Rays ◽  
Structure Formation ◽  
Hierarchical Structure ◽  
Milky Way ◽  
Cosmic Ray ◽  
Halo Stars ◽  
The Galaxy ◽  
Energy Dissipated ◽  
Kinematic Properties

AbstractThe energy dissipated by virialisation shocks during hierarchical structure formation of the Galaxy can exceed that injected by concomitant supernova (SN) explosions. Cosmic rays (CRs) accelerated by such shocks may therefore dominate over SNe in the production of 6Li through α + α fusion without co-producing Be and B. This process can give a more natural account of the observed 6Li abundance in metal-poor stars compared to standard SN CR scenarios. Future searches for correlations between the 6Li abundance and the kinematic properties of halo stars may constitute an important probe of how the Galaxy and its halo formed. Furthermore, 6Li may offer interesting clues to some fundamental but currently unresolved issues in cosmology and structure formation on sub-galactic scales.

scholarly journals Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements

2018 ◽  
Vol 68 (1) ◽  
pp. 377-404 ◽  
Author(s):  
Vincent Tatischeff ◽  
Stefano Gabici
Keyword(s):  
Cosmic Rays ◽  
Light Element ◽  
Cosmic Ray ◽  
Nuclear Interaction ◽  
Galactic Cosmic Rays ◽  
Light Elements ◽  
Halo Stars ◽  
The Standard Model ◽  
Low Metallicity ◽  
Galactic Cosmic Ray

In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.

Gamma-Ray Bursts as Probes of the Universe

2011 ◽  
Author(s):  
Joshua S. Bloom
Keyword(s):  
Star Formation ◽  
Cosmic Rays ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Ongoing Study ◽  
Observable Universe ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

This chapter focuses on how gamma-ray bursts (GRBs) are emerging as unique tools in the study of broad areas of astronomy and physics by virtue of their special properties. The unassailable fact about GRBs that makes them such great probes is that they are fantastically bright and so can be seen to the farthest reaches of the observable Universe. In parallel with the ongoing study of GRB events and progenitors, new lines of inquiry have burgeoned: using GRBs as unique probes of the Universe in ways that are almost completely divorced from the nature of GRBs themselves. Topics discussed include studies of gas, dust, and galaxies; the history of star formation; measuring reionization and the first objects in the universe; neutrinos, gravitational waves, and cosmic rays; quantum gravity and the expansion of the universe; and the future of GRBs.

Influence of supernovae, gamma-ray bursts, solar flares, and cosmic rays on the terrestrial environment

2008 ◽  
Author(s):  
Arnon Dar
Keyword(s):  
Solar Activity ◽  
Cosmic Rays ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Gamma Ray Bursts ◽  
The Sun ◽  
Terrestrial Environment ◽  
The Earth ◽  
The Galaxy ◽  
Threat To Life

Changes in the solar neighbourhood due to the motion of the sun in the Galaxy, solar evolution, and Galactic stellar evolution influence the terrestrial environment and expose life on the Earth to cosmic hazards. Such cosmic hazards include impact of near-Earth objects (NEOs), global climatic changes due to variations in solar activity and exposure of the Earth to very large fluxes of radiations and cosmic rays from Galactic supernova (SN) explosions and gamma-ray bursts (GRBs). Such cosmic hazards are of low probability, but their influence on the terrestrial environment and their catastrophic consequences, as evident from geological records, justify their detailed study, and the development of rational strategies, which may minimize their threat to life and to the survival of the human race on this planet. In this chapter I shall concentrate on threats to life from increased levels of radiation and cosmic ray (CR) flux that reach the atmosphere as a result of (1) changes in solar luminosity, (2) changes in the solar environment owing to the motion of the sun around the Galactic centre and in particular, owing to its passage through the spiral arms of the Galaxy, (3) the oscillatory displacement of the solar system perpendicular to the Galactic plane, (4) solar activity, (5) Galactic SN explosions, (6) GRBs, and (7) cosmic ray bursts (CRBs). The credibility of various cosmic threats will be tested by examining whether such events could have caused some of the major mass extinctions that took place on planet Earth and were documented relatively well in the geological records of the past 500 million years (Myr). A credible claim of a global threat to life from a change in global irradiation must first demonstrate that the anticipated change is larger than the periodical changes in irradiation caused by the motions of the Earth, to which terrestrial life has adjusted itself. Most of the energy of the sun is radiated in the visible range. The atmosphere is highly transparent to this visible light but is very opaque to almost all other bands of the electromagnetic spectrum except radio waves, whose production by the sun is rather small.

scholarly journals Cosmic Rays and the Dynamic Balance in the Large Magellanic Cloud

1990 ◽  
Vol 123 ◽  
pp. 537-541
Author(s):  
Carl E. Fichtel ◽  
Mehmet E. Ozel ◽  
Robert G. Stone
Keyword(s):  
Cosmic Rays ◽  
Gamma Ray ◽  
Dynamic Balance ◽  
Cosmic Ray ◽  
Large Magellanic Cloud ◽  
High Energy ◽  
Magellanic Cloud ◽  
Density Level ◽  
Energy Gamma ◽  
Galactic Dynamic

AbstractPresent and future measurement of the Large Magellanic Cloud (LMC) particularly in the radio and high energy gamma ray range offer the possibility of understanding the density and distribution of the cosmic rays in a galaxy other than our own and the role that they play in galactic dynamic balance. After a study of the consistency of the measurements and interpretation of the synchrotron radiation from our own galaxy, the cosmic ray distribution for the LMC is calculated under the assumption that the cosmic ray nucleon to electron ratio is the same and the relation to the magnetic fields are the same, although the implications of alternatives are discussed. It is seen that the cosmic ray density level appears to be similar to that in our own galaxy, but varying in position in a manner generally consistent with the concept of correlation with the matter on a broad scale.

scholarly journals Latitudinal and radial variation of >2 GeV/n protons and alpha-particles at solar maximum: ULYSSES COSPIN/KET and neutron monitor network observations

2003 ◽  
Vol 21 (6) ◽  
pp. 1295-1302 ◽  
Author(s):  
A. V. Belov ◽  
E. A. Eroshenko ◽  
B. Heber ◽  
V. G. Yanke ◽  
A. Raviart ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Neutron Monitor ◽  
Solar Minimum ◽  
Latitudinal Gradient ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Alpha Particles ◽  
Polar Regions

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. In 2000/2001 the spacecraft passed from the south to the north polar regions of the Sun in the inner heliosphere. In contrast to the first rapid pole to pole passage in 1994/1995 close to solar minimum, Ulysses experiences now solar maximum conditions. The Kiel Electron Telescope (KET) measures also protons and alpha-particles in the energy range from 5 MeV/n to >2 GeV/n. To derive radial and latitudinal gradients for >2 GeV/n protons and alpha-particles, data from the Chicago instrument on board IMP-8 and the neutron monitor network have been used to determine the corresponding time profiles at Earth. We obtain a spatial distribution at solar maximum which differs greatly from the solar minimum distribution. A steady-state approximation, which was characterized by a small radial and significant latitudinal gradient at solar minimum, was interchanged with a highly variable one with a large radial and a small – consistent with zero – latitudinal gradient. A significant deviation from a spherically symmetric cosmic ray distribution following the reversal of the solar magnetic field in 2000/2001 has not been observed yet. A small deviation has only been observed at northern polar regions, showing an excess of particles instead of the expected depression. This indicates that the reconfiguration of the heliospheric magnetic field, caused by the reappearance of the northern polar coronal hole, starts dominating the modulation of galactic cosmic rays already at solar maximum.Key words. Interplanetary physics (cosmic rays; energetic particles) – Space plasma physics (charged particle motion and acceleration)

scholarly journals Gamma-ray emitting supernova remnants as the origin of Galactic cosmic rays

2015 ◽  
Vol 2 ◽  
pp. 57-62 ◽  
Author(s):  
M. Kroll ◽  
J. Becker Tjus ◽  
B. Eichmann ◽  
N. Nierstenhöfer
Keyword(s):  
Cosmic Rays ◽  
Energy Budget ◽  
Thermal Energy ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Below The Knee ◽  
Individual Contributions ◽  
First Time

Abstract. It is generally believed that the cosmic ray spectrum below the knee is of Galactic origin, although the exact sources making up the entire cosmic ray energy budget are still unknown. Including effects of magnetic amplification, Supernova Remnants (SNR) could be capable of accelerating cosmic rays up to a few PeV and they represent the only source class with a sufficient non-thermal energy budget to explain the cosmic ray spectrum up to the knee. Now, gamma-ray measurements of SNRs for the first time allow to derive the cosmic ray spectrum at the source, giving us a first idea of the concrete, possible individual contributions to the total cosmic ray spectrum. In this contribution, we use these features as input parameters for propagating cosmic rays from its origin to Earth using GALPROP in order to investigate if these supernova remnants reproduce the cosmic ray spectrum and if supernova remnants in general can be responsible for the observed energy budget.

scholarly journals Interpreting correlated observations of cosmic rays and gamma-rays from Centaurus A with a proton blazar inspired model

2020 ◽  
Vol 500 (1) ◽  
pp. 1087-1094
Author(s):  
Prabir Banik ◽  
Arunava Bhadra ◽  
Abhijit Bhattacharyya
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Energy Scale ◽  
Electromagnetic Spectrum ◽  
Ultrahigh Energy ◽  
Large Area ◽  
Centaurus A

ABSTRACT The nearest active radio galaxy Centaurus (Cen) A is a gamma-ray emitter in GeV–TeV energy scale. The high energy stereoscopic system (HESS) and non-simultaneous Fermi–Large Area Telescope observation indicate an unusual spectral hardening above few GeV energies in the gamma-ray spectrum of Cen A. Very recently the HESS observatory resolved the kilo parsec (kpc)-scale jets in Centaurus A at TeV energies. On the other hand, the Pierre Auger Observatory (PAO) detects a few ultrahigh energy cosmic ray (UHECR) events from Cen-A. The proton blazar inspired model, which considers acceleration of both electrons and hadronic cosmic rays in active galactic nuclei (AGN) jet, can explain the observed coincident high-energy neutrinos and gamma-rays from Ice-cube detected AGN jets. Here, we have employed the proton blazar inspired model to explain the observed GeV–TeV gamma-ray spectrum features including the spectrum hardening at GeV energies along with the PAO observation on cosmic rays from Cen-A. Our findings suggest that the model can explain consistently the observed electromagnetic spectrum in combination with the appropriate number of UHECRs from Cen A.

scholarly journals Supernova remnants and the origin of cosmic rays

2013 ◽  
Vol 9 (S296) ◽  
pp. 305-314
Author(s):  
Jacco Vink
Keyword(s):  
Synchrotron Radiation ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Long Time ◽  
Gamma Ray Emission

AbstractSupernova remnants have long been considered to be the dominant sources of Galactic cosmic rays. For a long time the prime evidence consisted of radio synchrotron radiation from supernova remnants, indicating the presence of electrons with energies of several GeV. However, in order to explain the cosmic ray energy density and spectrum in the Galaxy supernova remnant should use 10% of the explosion energy to accelerate particles, and about 99% of the accelerated particles should be protons and other atomic nuclei.Over the last decade a lot of progress has been made in providing evidence that supernova remnant can accelerate protons to very high energies. The evidence consists of, among others, X-ray synchrotron radiation from narrow regions close to supernova remnant shock fronts, indicating the presence of 10-100 TeV electrons, and providing evidence for amplified magnetic fields, gamma-ray emission from both young and mature supernova remnants. The high magnetic fields indicate that the condition for accelerating protons to >1015 eV are there, whereas the gamma-ray emission from some mature remnants indicate that protons have been accelerated.

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