High-energy Particle Emission Research Articles

Wakefield acceleration in the universe

The important role of magnetic fields in the phenomena in and evolution of the Universe is well appreciated. A salient example of this is to make (often episodic) large magnetic fields in AGN accretion disks and their emanation of well-collimated and longitudinally extended astrophysical jets. Such typical cases or related astrophysical processes, we find, provide a fertile ground for exciting large-amplitude oscillations in the magnetic fields that constitute the spine of the jets. The energy sources of these oscillations can be traced originally to the gravitational energy of the central object. During their long propagation along the jet, because of the gradual changes of the density and magnetic fields, these large magnetic pulsations turn into relativistic amplitude electromagnetic (EM) pulses, which in turn induce intense wakefields that are capable of acceleration of electrons, positrons, and ions to high energies. In this review, we survey a variety of astrophysical objects ranging from as large as the cosmic AGN accretion disks and their jets to as small as microquasars, to find or predict that there exist common astrophysical processes of emission of high-energy particles and gamma (and other EM) emissions. A variety of these objects will be ideally observed and studied in the multimessenger astrophysical observations. One example that already stuck out was the case of the simultaneous observations of gravitational wave emission and gamma-ray pulse from the collision of the two neutron stars and their subsequent structure formation (such as a disk) around them.

Synthetic Neutrino Imaging of a Microquasar

Microquasar binary stellar systems emit electromagnetic radiation and high-energy particles over a broad energy spectrum. However, they are so far away that it is hard to observe their details. A simulation offers the link between relatively scarce observational data and the rich theoretical background. In this work, high-energy particle emission from simulated twin microquasar jets is calculated in a unified manner. From the cascade of emission within an element of jet matter to the dynamic and radiative whole jet model, the series of physical processes involved are integrated together. A programme suite assembled around model data produces synthetic images and spectra directly comparable to potential observations by contemporary arrays. The model is capable of describing a multitude of system geometries, incorporating increasing levels of realism depending on need and available computational resources. As an application, the modelling process is applied to a typical microquasar, which is synthetically observed from different angles using various imaging geometries. Furthermore, the resulting intensities are comparable to the sensitivity of existing detectors. The combined background emission from a potential distribution of microquasars is also modelled.

Emission of High-Energy Protons and Photons in Heavy-Ion Collisions Treated on the Basis of a Hydrodynamic Approach with a Nonequilibrium Equation of State

A hydrodynamic approach involving a nonequilibrium equation of state is used in describing heavy-ion collisions at medium and intermediate energies. The double differential cross sections for proton and photon emission in collisions of various nuclei are calculated in developing this approach with allowance for nuclear-viscosity effects and amendments introduced by the microcanonical distribution. The results agree everywhere, including the cumulative region of the spectrum, with available experimental data on the emission of high-energy particles. The approach in question permits reproducing high-momentum distributions of protons from the reaction $${}^{12}\textrm{C}+\,^{9}\textrm{Be}\to p+X$$ at the $${}^{12}$$ C ion energies of 300, 600, 950, and 2000 MeV per nucleon and the energy spectra of hard photons from the reaction $${}^{12}\textrm{C}+\,^{9}\textrm{Be}\to\gamma+X$$ at the $${}^{12}$$ C ion energies of 2.0 and 3.2 GeV per nucleon.

On the relative importance of hadronic emission processes along the jet axis of active galactic nuclei

ABSTRACTWith the coincident detection of a gamma-ray flare and a neutrino from the blazar TXS 0506+056, active galactic nuclei (AGNs) have been put into focus as possible sources of the diffuse neutrino flux. We present a space and time-resolved model of the high-energy particle emission of a plasmoid assumed to travel along the axis of an AGN jet at relativistic speed. This was achieved by modifying the publicly available crpropa (version 3.1+) propagation framework that in our work is capable of being applied to source physics on sub-kpc scales. The propagation of a population of primary protons is modelled in a purely turbulent magnetic field and we take into account interactions of these protons with photons scattered from the accretion disc, synchrotron radiation emitted by ambient relativistic electrons, as well with themselves and with other ambient matter. Our model produces a PeV-neutrino flare caused mainly by photohadronic interactions of primaries with the accretion disc field. Secondary high-energy gamma-rays partly attenuate with the ambient photon fields whose combined optical depths achieve their minimal opacity for photons of around 10 TeV. Thus, our model is well capable of producing neutrino flares with a significantly reduced emission of gamma-rays in jets with a hadronic jet component that in the future can be fit to specific AGN flare scenarios.

Neutron Star Mergers: Probing the EoS of Hot, Dense Matter by Gravitational Waves

Gravitational waves, electromagnetic radiation, and the emission of high energy particles probe the phase structure of the equation of state of dense matter produced at the crossroad of the closely related relativistic collisions of heavy ions and of binary neutron stars mergers. 3 + 1 dimensional special- and general relativistic hydrodynamic simulation studies reveal a unique window of opportunity to observe phase transitions in compressed baryon matter by laboratory based experiments and by astrophysical multimessenger observations. The astrophysical consequences of a hadron-quark phase transition in the interior of a compact star will be focused within this article. Especially with a future detection of the post-merger gravitational wave emission emanated from a binary neutron star merger event, it would be possible to explore the phase structure of quantum chromodynamics. The astrophysical observables of a hadron-quark phase transition in a single compact star system and binary hybrid star merger scenario will be summarized within this article. The FAIR facility at GSI Helmholtzzentrum allows one to study the universe in the laboratory, and several astrophysical signatures of the quark-gluon plasma have been found in relativistic collisions of heavy ions and will be explored in future experiments.

Emission of high energy particles in heavy ion collisions and a non-equilibrium equation of state

A hydrodynamic approach with a non-equilibrium equation of state is used to describe the collisions of heavy ions at medium and intermediate energies. In the development of this approach, with the inclusion of nuclear viscosity effects and the introduction of an amendment to the microcanonical distribution, the double differential cross sections of proton emission in collisions of different nuclei are calculated, which are in agreement with the available experimental data on the emission of high-energy particles, including the cumulative spectral region.

Spatial Organization of Seven Extreme Solar Energetic Particle Events

Abstract Emission of relativistic protons and helium responsible for extreme solar particle events (ground level enhancements (GLEs)) is often structured. We investigate its organization depending on the eruption stage characterized by the heliocentric height of associated coronal mass ejections (CMEs). Seven GLEs are considered: events on 1997 November 6, 1998 May 2, 2000 July 14, 2001 December 26, 2003 November 2, 2006 December 13, and 2012 May 17, which are half of the SOlar and Heliospheric Observatory (SOHO )-era GLEs, excluding very weak events. Count-rate profiles of the GLEs plotted as a function of the CME height reveal two types (or two components) of the high-energy particle emission. The first component rises in a step-like manner during the CME transit from 2 R ⊙ to 3 R ⊙, when the CME exits from predominantly closed coronal magnetic structures, irrespective of the CME speed (type H). This component is of coronal origin. The second component of the GLE-producing particles starts to rise when CME is at about 4 R ⊙, achieves its maximum at 6–10 R ⊙, and declines shortly after that (type J). The type J particle injection into the interplanetary space coincides with the decametric–hectometric radio burst complex that includes enhanced emission of type II and concurrent low-frequency type III bursts, indicative of the CME interaction with a streamer-like structure at a few solar radii from the Sun. Those could be delayed particles from the flare region. A possible additional contribution of the CME-bow-shock acceleration in unstructured solar wind is not large in the two considered types of events.

Investigating the Origins of Two Extreme Solar Particle Events: Proton Source Profile and Associated Electromagnetic Emissions

Abstract We analyze the high-energy particle emission from the Sun in two extreme solar particle events in which protons are accelerated to relativistic energies and can cause a significant signal even in the ground-based particle detectors. Analysis of a relativistic proton event is based on modeling of the particle transport and interaction, from a near-Sun source through the solar wind and the Earth’s magnetosphere and atmosphere to a detector on the ground. This allows us to deduce the time profile of the proton source at the Sun and compare it with observed electromagnetic emissions. The 1998 May 2 event is associated with a flare and a coronal mass ejection (CME), which were well observed by the Nançay Radioheliograph, thus the images of the radio sources are available. For the 2003 November 2 event, the low corona images of the CME liftoff obtained at the Mauna Loa Solar Observatory are available. Those complementary data sets are analyzed jointly with the broadband dynamic radio spectra, EUV images, and other data available for both events. We find a common scenario for both eruptions, including the flare’s dual impulsive phase, the CME-launch-associated decimetric-continuum burst, and the late, low-frequency type III radio bursts at the time of the relativistic proton injection into the interplanetary medium. The analysis supports the idea that the two considered events start with emission of relativistic protons previously accelerated during the flare and CME launch, then trapped in large-scale magnetic loops and later released by the expanding CME.

The role of the diffusive protons in the gamma-ray emission of SNR RX J1713.7-3946

AbstractRX J1713.7-3946 is a prototype in the γ-ray-bright supernova remnants (SNRs) and is in continuing debates on its hadronic versus leptonic origin of the γ-ray emission. We explore the role played by the diffusive relativistic protons that escape from the SNR shock wave in the γ-ray emission, apart from the emission of high energy particles from the inside of the SNR. In the scenario that the SNR shock propagates in a clumpy molecular cavity, we consider that the γ-ray emission from the inside of the SNR may either arise from the IC scattering or from the interaction between the trapped energetic protons and the shocked clumps. The dominant origin between them depends on the electron-to-proton number ratio. The surrounding molecular cavity wall is considered to also produce γ-ray emission due to the “illumination” by the diffusive protons that escaped from the shock wave during the expansion history. The broad-band spectrum can be well explained by this two-zone model, in which the γ-ray emission from the inside governs the TeV band, while the outer emission component substantially contributes to the GeV γ-rays. The two-zone model can also explain the TeV γ-ray radial brightness profile that significantly stretches beyond the nonthermal X-ray emitting region.

Spallation reactions: A successful interplay between modeling and applications

The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200 MeV deuterons and 400 MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. The same year R. Serber describes the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a worskhop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.

Modeling the relativistic runaway electron avalanche and the feedback mechanism with GEANT4.

This paper presents the first study that uses the GEometry ANd Tracking 4 (GEANT4) toolkit to do quantitative comparisons with other modeling results related to the production of terrestrial gamma ray flashes and high-energy particle emission from thunderstorms. We will study the relativistic runaway electron avalanche (RREA) and the relativistic feedback process, as well as the production of bremsstrahlung photons from runaway electrons. The Monte Carlo simulations take into account the effects of electron ionization, electron by electron (Møller), and electron by positron (Bhabha) scattering as well as the bremsstrahlung process and pair production, in the 250 eV to 100 GeV energy range. Our results indicate that the multiplication of electrons during the development of RREAs and under the influence of feedback are consistent with previous estimates. This is important to validate GEANT4 as a tool to model RREAs and feedback in homogeneous electric fields. We also determine the ratio of bremsstrahlung photons to energetic electrons Nγ/Ne. We then show that the ratio has a dependence on the electric field, which can be expressed by the avalanche time τ(E) and the bremsstrahlung coefficient α(ε). In addition, we present comparisons of GEANT4 simulations performed with a “standard” and a “low-energy” physics list both validated in the 1 keV to 100 GeV energy range. This comparison shows that the choice of physics list used in GEANT4 simulations has a significant effect on the results.Key PointsTesting the feedback mechanism with GEANT4Validating the GEANT4 programming toolkitStudy the ratio of bremsstrahlung photons to electrons at TGF source altitude

THE EFFECT OF TURBULENCE INTERMITTENCE ON THE EMISSION OF SOLAR ENERGETIC PARTICLES BY CORONAL AND INTERPLANETARY SHOCKS

Major solar energetic particle events are associated with shock waves in solar corona and solar wind. Fast scattering of charged particles by plasma turbulence near the shock wave increases the efficiency of the particle acceleration in the shock, but prevents particles from escaping ahead of the shock. However, the turbulence energy levels in neighboring magnetic tubes of solar wind may differ from each other by more than one order of magnitude. We present the first theoretical study of accelerated particle emission from an oblique shock wave propagating through an intermittent turbulence background that consists of both highly turbulent magnetic tubes, where particles are accelerated, and quiet tubes, via which the accelerated particles can escape to the non-shocked solar wind. The modeling results imply that the presence of the fast transport channels penetrating the shock and cross-field transport of accelerated particles to those channels may play a key role in high-energy particle emission from distant shocks and can explain the prompt onset of major solar energetic particle events observed near the Earth's orbit.

DETECTION OF NEUTRINOS FROM MICRO-QUASARS I

Using the neutrino intensity obtained from models for high-energy particle-emission from low-mass micro-quasars, we calculate the neutrino flux with and without including neutrino oscillations. We show that the neutrino flux from a micro-quasar is affected by neutrino oscillations. The effect reflects upon the increase in the time of observation, for km-scale neutrino detector.

Electromagnetic and neutron emissions from brittle rocks failure: Experimental evidence and geological implications

It has been observed energy emission in the form of electromagnetic radiation, clearly indicating charge redistribution, and neutron bursts, necessarily involving nuclear reactions, during the failure process of quasi-brittle materials such as rocks, when subjected to compression tests. The material used is Luserna stone, which presents a very brittle behaviour during compression failure. The observed phenomenon of high-energy particle emission, i.e., electrons and neutrons, can be explained in the framework of the superradiance applied to the solid state, where individual atoms lose their identity and become part of different plasmas, electronic and nuclear. Since the analysed material contains iron, it can be conjectured that piezonuclear reactions involving fission of iron into aluminum, or into magnesium and silicon, should have occurred during compression damage and failure. These complex phenomenologies are confirmed by Energy Dispersive X-ray Spectroscopy (EDS) tests conducted on Luserna stone specimens, and found additional evidences at the Earth’s Crust scale, where electromagnetic and neutron emissions are observed just in correspondence with major earthquakes. In this context, the effects of piezonuclear reactions can be also considered from a geophysical and geological point of view.

On the hardening of the spectrum of high-energy particles formed in heavy-ion collisions considered within the framework of the hydrodynamic approach

The emission of high-energy particles in the 16O + 197Au ion collision at an energy of 20 MeV/nucleon is considered in the context of hot spot time evolution with allowance for the hydrodynamic compression and expansion stages. In addition to our earlier consideration of this model, the evaporation of formed particles is included in spectrum calculation at the early (hot) stage of hot spot evolution. This leads to particle spectrum hardening in its high-energy part, in agreement with the experimental data.

On The Hardening of The Spectrum of High-Energy Particles Formed in Heavy-Ion Collisions Considered within The Framework of The Hydrodynamic Approach

The emission of high-energy particles in 16O + 197Au collisions at energy 20 MeV / nucleon is considered within the framework of the time evolution of a hot spot taking into account the hydrodynamic compression and expansion stages. In addition, the evaporation of the particles that are formed in the early (hot) stage of the evolution of the hot spot is included in the calculation of the spectrum. This leads to a hardening of the particle spectrum in its high-energy part, which is in agreement with experimental data.

On The Hardening of The Spectrum of High-Energy Particles Formed in Heavy-Ion Collisions Considered within The Framework of The Hydrodynamic Approach

The emission of high-energy particles in 16O + 197Au collisions at energy 20 MeV / nucleon is considered within the framework of the time evolution of a hot spot taking into account the hydrodynamic compression and expansion stages. In addition, the evaporation of the particles that are formed in the early (hot) stage of the evolution of the hot spot is included in the calculation of the spectrum. This leads to a hardening of the particle spectrum in its high-energy part, which is in agreement with experimental data.

Cold fusion and reproducibility

Bernard Feldman is to be commended for his thoughtful review of David Goodstein’s new book. However, Feldman has seriously misrepresented the scientific facts about the contentious topic of cold fusion. In particular, he suggests that Goodstein’s “sympathetic view toward scientists working in cold fusion” is misguided because cold fusion is “a prime example of a field characterized by unverified results.” Although the vast majority of the early attempts to reproduce the associated effects failed, not only were the effects reproduced, but with time, the reasons for the difficulties that were encountered have become well understood.An important source of confusion is that Martin Fleischmann and Stanley Pons did not discover a colder version of conventional fusion. They discovered something else: a new form of aneutronic nuclear fusion, involving a two-deuteron reaction in which helium-4 is created without the emission of high-energy particles or gamma rays. 1–3 1. M. H. Miles, R. A. Hollins, B. F. Bush, J. J. Lagowski, R. E. Miles, J. Electroanal. Chem. 346, 99 (1993), available at http://www.lenr-canr.org/acrobat/MilesMcorrelatio.pdf.2. M. H. Miles, B. F. Bush, K. B. Johnson, Anomalous Effects in Deuterated Systems, Naval Air Warfare Center Weapons Division, China Lake, CA (1996), available at http://www.lenr-canr.org/acrobat/MilesManomalousea.pdf.3. P. L. Hagelstein, M. C. H. McKubre, D. J. Nagel, T. A. Chubb, R. J. Hekman, in Condensed Matter Nuclear Science: Proceedings of the 11th International Conference on Cold Fusion, J. -P. Biberian, ed., World Scientific, Hackensack, NJ (2006), p. 23, available at http://www.lenr-canr.org/acrobat/Hagelsteinnewphysica.pdf. It is not altogether surprising that Feldman is unaware of that. Effectively, mainstream scientific journals have maintained an embargo against cold-fusion papers that report positive findings. That failure has, in fact, become a topic in the mainstream ethics-in-science literature. 4 4. Special issue on cold fusion, Accountability Res. 8 (2000). All the papers in this special issue are available at http://www.lenr-canr.org. Twenty-one years after cold fusion was first announced, a more “normal” dialog about the subject 5 5. D. Goodstein, Accountability Res. 8, 59 (2000), available at http://www.lenr-canr.org/acrobat/GoodsteinDwhateverha.pdf. is badly needed.REFERENCESSection:ChooseTop of pageREFERENCES <<1. M. H. Miles, R. A. Hollins, B. F. Bush, J. J. Lagowski, R. E. Miles, J. Electroanal. Chem. 346, 99 (1993), available at http://www.lenr-canr.org/acrobat/MilesMcorrelatio.pdf. Google ScholarCrossref, ISI2. M. H. Miles, B. F. Bush, K. B. Johnson, Anomalous Effects in Deuterated Systems, Naval Air Warfare Center Weapons Division, China Lake, CA (1996), available at http://www.lenr-canr.org/acrobat/MilesManomalousea.pdf. Google ScholarCrossref3. P. L. Hagelstein, M. C. H. McKubre, D. J. Nagel, T. A. Chubb, R. J. Hekman, in Condensed Matter Nuclear Science: Proceedings of the 11th International Conference on Cold Fusion, J. -P. Biberian, ed., World Scientific, Hackensack, NJ (2006), p. 23, available at http://www.lenr-canr.org/acrobat/Hagelsteinnewphysica.pdf. Google ScholarCrossref4. Special issue on cold fusion, Accountability Res. 8 (2000). All the papers in this special issue are available at http://www.lenr-canr.org. Google Scholar5. D. Goodstein, Accountability Res. 8, 59 (2000), available at http://www.lenr-canr.org/acrobat/GoodsteinDwhateverha.pdf. Google ScholarCrossref© 2010 American Institute of Physics.

High-energy particle emission from galena and pyrite bombarded with Cs and O ions

The ejection of energetic particles during steady-state ion surface bombardment has been investigated by means of a dynamic computer simulation as well as in a secondary ion mass spectrometry (SIMS)/low-energy ion scattering from surfaces (LEIS) experiment. The emphasis of this comparative study is on the mass dependence of high-energy tails in sputtering and backscattering for the bombardment of galena (PbS) and pyrite (FeS 2) with keV energy ion beam of cesium and oxygen. In the experiment, kinetic energy distributions of sputtered secondary ions ( S +, Fe +, Pb +, S − ), as well as backscattered or re-sputtered primary ions ( Cs +, O +, O − ), have been measured on a modified Cameca IMS-3f magnetic sector mass spectrometer for keV cesium (Cs +) and oxygen ( O 2 +, O − ) bombardment of galena and pyrite. Ejection of high-energy particles, with emission energies of up to ∼40% or up to ∼60% of the bombarding energy for sputtering of the lighter component (S ±) with cesium or oxygen, respectively, and of up to ∼40% (Cs +) and ∼80% (O ±) for backscattering, has been observed for PbS. The computer simulations were based on the well-known MARLOWE code. In order to model the change of the stoichiometry of the binary compounds, dynamic modification of the target composition in the near-surface region was introduced. Cs incorporation was included, and a relative enrichment of the metallic component (Pb, Fe) in the top few layers due to preferential sputtering of sulfur was allowed. The computer simulations provide information on the formation of altered layer under sputter equilibrium as well as on the energy and angular emission distributions of sputtered and backscattered particles in steady-state conditions. Multiple scattering of Cs projectiles and dynamic re-sputtering of cesium that was previously incorporated in the altered near-surface region can be distinguished in the simulation, and matched with the experimental observations. In addition, information on the inverse velocity dependence of ion formation can be obtained from the comparison of the SIMS/LEIS experiment and the computer simulation.

On the 34Si emission of 242Cm

A 34Si-decay of 242Cm has been reported by Oglobin et al. But an interpretation of this 34Si emission as a ternary high-energy particle emission accompanying the fission of 242Cm can be proposed as well.