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Journal articles on the topic 'Nucleon and gamma ray emission'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 February 2022

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1

Vilmer, N. "Solar Hard X-Ray and Gamma-Ray Observations from GRANAT." International Astronomical Union Colloquium 142 (1994): 611–21. http://dx.doi.org/10.1017/s0252921100077885.

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AbstractHard X-rays and gamma-rays are the most direct signature of the energetic electrons and ions which are accelerated during solar flares. Since the beginning of 1990 the PHEBUS instrument and the SIGMA anticoincidence shield aboard GRANAT have provided hard X-ray and gamma-ray observations of solar bursts in the energy range 0.075-124 and 0.200-15 MeV, respectively. After a brief description of the experiments, we present some results obtained on solar bursts recorded in 1990 and 1991 June. Special emphasis is given to the results related with particle acceleration during solar flares.The first part of the review is devoted to the constraints obtained on the electron acceleration timescale through the analysis of the temporal characteristics of the bursts. Combined studies of hard X-ray and gamma-ray emissions from PHEBUS and radio emissions from the Nançay Multifrequency Radioheliograph are used to infer constraints on the coronal magnetic topology involved in flares. The characteristics (location, spectrum) of the radio-emitting sources are found to vary within a flare from one hard X-ray peak to the other. Hard X-ray and gamma-ray burst onsets and rapid increases of the > 10 MeV emission are coincident with changes in the associated radio emission pattern. These results will be discussed in the context of the flare energy release.The second part of the paper concerns the heliocentric angle distribution of > 10 MeV events and presents more detailed observations of some of the largest flares in the gamma-ray line and the high-energy domains produced by ultrarelativistic electrons and > 100 MeV nucleon−1 ions. The PHEBUS observations of the gamma-ray line flare of 11 June 1991 have been used to deduce the hardness of the accelerated ion spectrum. The link between the main part of the flare and the late long-lasting >50 MeV emission detected by EGRET/COMPTON is discussed. Finally some observations of the large 1990 May 24 flare which produced a large neutron event at ground level are presented.Subject headings: acceleration of particles — Sun: flares — Sun: radio radiation — Sun: X-rays, gamma rays

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SINGH, N. L., S. MUKHERJEE, and M. S. GADKARI. "EXCITATION FUNCTIONS OF ALPHA INDUCED REACTIONS ON NATURAL NICKEL UP TO 50 MeV." International Journal of Modern Physics E 14, no. 04 (June 2005): 611–29. http://dx.doi.org/10.1142/s021830130500348x.

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Excitation functions have been measured for alpha-particle induced reactions on natural nickel leading to the production of 62 Zn , 61 Cu , 56,57 Ni and 56,58 Co radioisotopes up to 50 MeV by the activation method and gamma-ray spectrometry. Most of these radioisotopes are produced by one or two alpha-particle emissions and a few nucleon emissions. The excitation functions were compared with semi-classical models codes, like ALICE/90, which includes a shell corrected level density formulation and the COMPLET, which takes into account angular momentum removal effects. In the case of multi-nucleon emission channels, ALICE/90 gives fairly good agreement. The COMPLET code on the other hand, explains the α-particle emission channels in a more convincing manner.

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3

Fukazawa, Yasushi. "X-ray probing of NGC 1275 nuclear region with Hitomi, Swift, and Suzaku." Proceedings of the International Astronomical Union 14, S342 (May 2018): 118–21. http://dx.doi.org/10.1017/s1743921318007366.

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AbstractNGC 1275 has been known as a ppint-like X-ray source with a continuum and a Fe-K line. Unlike radio and GeV/TeV gamma-ray emissions, origin of X-ray emission is not yet understood; is it a jet emission like blazars or an accretion corona emission like Seyfert galaxies. X-ray emission is important to determine the SED of jet emission to constrain jet parameters and also understand the relation between accretion and jet. Here we report a recent X-ray probing of NGC 1275 nuclear region with Hitomi/SXS, Swift/XRT, and Suzaku/XIS. Hitomi/SXS gave the first opportunity to measure a Fe-K line of AGNs with several eV resolution. The line center is consistent with the neutral iron emission, and the width is constrained to be 500-1600 km/s (FWHM). This ruled out the origin of broad line region and inner accretion disk. A low-covering-fraction molecular torus or a rotating molecular disk around pc scales, illuminated by accretion corona emission, is suggested as a possible origin. For the continuum emission, Suzaku/XIS monitor observations revealed that the X-ray flux has gradually increased as the GeV gamma-ray flux. Swift/XRT showed a several-days flux increase, associated with the GeV gamma-ray flare. These results on the continuum emission suggests a contribution of jet emission to the X-ray emission. Based on the combined results of Fe-K line and continuum, we discuss some scenarios for X-ray emitting region.

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Murphy, Ronald J., Gerald H. Share, J. Eric Grove, W. Neil Johnson, James D. Kurfess, William R. Purcell, K. McNaron‐Brown, and Reuven Ramaty. "Limits on Nuclear Gamma‐Ray Emission from Orion." Astrophysical Journal 473, no. 2 (December 20, 1996): 990–97. http://dx.doi.org/10.1086/178209.

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5

Ramaty, R., and N. Mandzhavidze. "Gamma-rays from Solar Flares." Symposium - International Astronomical Union 195 (2000): 123–32. http://dx.doi.org/10.1017/s0074180900162850.

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Gamma-ray emission is the most direct diagnostic of energetic ions and relativistic electrons in solar flares. Analysis of solar flare gamma-ray data has shown: (i) ion acceleration is a major consequence of flare energy release, as the total flare energy in accelerated particles appears to be equipartitioned between ≳ 1 MeV/nucleon ions and ≳ 20 keV electrons, and amounts to an important fraction of the total energy release; (ii) there are flares for which over 50% of the energy is in a particles and heavier ions; (iii) in both impulsive and gradual flares, the particles that interact at the Sun and produce gamma rays are essentially always accelerated by the same mechanism that operates in impulsive flares, probably stochastic acceleration through gyroresonant wave particle interaction; and (iv) gamma-ray spectroscopy can provide new information on solar abundances, for example the site of the FIP-bias onset and the photospheric 3He abundance. We propose a new technique for the investigation of mass motion and mixing in the solar atmosphere: the observations of gamma-ray lines from long-term radioactivity produced by flare accelerated particles.

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Miyahara, Hiroshi, Keiji Katoh, Keiichi Ikeda, Kazuo Fujiki, Ichirou Nishinaka, Kazuaki Tsukada, Yuichiro Nagame, Masato Asai, Sin-ichi Ichikawa, and Hiromitsu Haba. "Gamma-ray emission probability measurement of 149Eu." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 533, no. 3 (November 2004): 404–8. http://dx.doi.org/10.1016/j.nima.2004.06.171.

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7

Kim, J. B., J. Morel, M. Etcheverry, N. Coursol, D. Trubert, O. Constantinescu, S. A. Karamian, Yu Ts Oganessian, Ch Briancon, and M. Hussonnois. "Precise measurement of gamma-ray energies and gamma-ray emission probabilities in178m2Hf decay." Journal of Radioanalytical and Nuclear Chemistry 215, no. 2 (January 1997): 229–33. http://dx.doi.org/10.1007/bf02034469.

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8

Davydov, A. V. "Once again on the duration of nuclear gamma-ray-emission and gamma-ray-absorption processes." Physics of Atomic Nuclei 74, no. 1 (January 2011): 11–12. http://dx.doi.org/10.1134/s1063778811010030.

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9

Galper, A. M., S. I. Suchkov, N. P. Topchiev, I. V. Arkhangelskaja, A. I. Arkhangelskiy, A. V. Bakaldin, Yu V. Gusakov, et al. "Precision Measurements of High-Energy Cosmic Gamma-Ray Emission with the GAMMA-400 Gamma-Ray Telescope." Physics of Atomic Nuclei 80, no. 6 (November 2017): 1141–45. http://dx.doi.org/10.1134/s1063778817060096.

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10

Martin, P., G. Dubus, P. Jean, V. Tatischeff, and C. Dosne. "Gamma-ray emission from internal shocks in novae." Astronomy & Astrophysics 612 (April 2018): A38. http://dx.doi.org/10.1051/0004-6361/201731692.

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Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods. We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results. The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to ~100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10−5–10−4 M⊙ expands in a homologous way with a maximum velocity of 1000–2000 km s−1, followed within a day by a wind with a velocity <2000 km s−1 and a mass-loss rate of 10−4–10−3 M⊙ yr−1 declining over a time scale of a few days. Because of the large uncertainties in the measurements, many parameters of the problem are degenerate and/or poorly constrained except for the wind velocity, the relatively low values of which result in the majority of best-fit models having gamma-ray spectra with a high-energy turnover below ~10 GeV. Our typical model is able to account for the main features in the observations of the recent gamma-ray nova ASASSN-16ma. Conclusions. The internal shock model can account for the gamma-ray emission of the novae detected by Fermi LAT. Gamma-ray observations hold potential for probing the mechanism of mass ejection in novae, but should be combined to diagnostics of the thermal emission at lower energies to be more constraining.

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Kosmas, Odysseas, and Theodoros Smponias. "Simulations of Gamma-Ray Emission from Magnetized Microquasar Jets." Advances in High Energy Physics 2018 (October 31, 2018): 1–11. http://dx.doi.org/10.1155/2018/9602960.

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In this work, we simulate γ-rays created in the hadronic jets of the compact object in binary stellar systems known as microquasars. We utilize as the main computational tool the 3D relativistic magnetohydrodynamical code PLUTO combined with in-house derived codes. Our simulated experiments refer to the SS433 X-ray binary, a stellar system in which hadronic jets have been observed. We examine two new model configurations that employ hadron-based emission mechanisms. The simulations aim to explore the dependence of the γ-ray emissions on the dynamical as well as the radiative properties of the jet (hydrodynamic parameters of the mass-flow density, gas-pressure, temperature of the ejected matter, high energy proton population inside the jet plasma, etc.). The results of the two new scenarios of initial conditions for the microquasar stellar system studied are compared to those of previously considered scenarios.

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12

WANG, WEI. "GALACTIC Al 1.8 MeV GAMMA-RAY SURVEYS WITH INTEGRAL." International Journal of Modern Physics: Conference Series 23 (January 2013): 48–53. http://dx.doi.org/10.1142/s2010194513011069.

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26 Al is a long-life radioactive isotope with a half lifetime of near 1 Myr. The origin of Galactic 26 Al is dominated by massive stars and their core-collapse supernovae. Detections of 1809 keV emission from 26 Al provide direct evidence that nucleosynthesis is ongoing in the Galaxy. The gamma-ray line shapes reflect the dynamics of the ejected isotopes in the interstellar medium and then probe properties of ISM and Galactic rotation effect. Gamma-ray emissions of 26 Al in the Galaxy are studied with the high spectral resolution INTEGRAL spectrometer (SPI). We carry out the first spectral survey of 26 Al gamma-ray line emission along the Galactic plane. The 26 Al line energy shifts reflect the large-scale Galactic rotation. The 26 Al intensity is brighter in the 4th than in the 1st quadrant (ratio ~ 1.3); the 26 Al line toward the direction of the Aquila region appears somewhat broadened; a latitudinal scale height of [Formula: see text] pc for 26 Al in the inner Galaxy is determined. Strong 26 Al emission signal is detected in the nearby star-formation regions Sco-Cen and Cygnus. The 26 Al line shapes in star-formation regions provide a clue to constrain the kinematic properties of ISM. In addition, we derive the flux ratio of 60 Fe /26 Al ~ 15% which can be directly compared with theoretical predictions. More theoretical work on nuclear reactions, massive star evolution models deserves improvements.

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13

Naito, T., and F. Takahara. "High energy gamma-ray emission from supernova remnants." Journal of Physics G: Nuclear and Particle Physics 20, no. 3 (March 1, 1994): 477–86. http://dx.doi.org/10.1088/0954-3899/20/3/009.

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14

Shakhmuratov, R. N. "Influence of Giant Nuclear-spin Polarisation on Resonant Gamma-ray Absorption and Emission." Australian Journal of Physics 51, no. 2 (1998): 339. http://dx.doi.org/10.1071/p97057.

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We propose a new scheme of gamma-quanta amplification without inversion. Laser pumping of electron states creates giant nuclear-spin polarisation via the hyperfine interaction. This results in extreme cooling of the ground-state nuclear spin in a projection which does not absorb both laser pump and gamma-quanta according to selection rules for these transitions. Induced emission from the nuclear excited state is not influenced by the pump. Therefore gamma-quanta travelling inside the pump beam have an opportunity to induce stimulated emission without subsequent quenching by ground state nuclei.

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15

Brady, C. S., C. P. Ridgers, T. D. Arber, and A. R. Bell. "Gamma-ray emission in near critical density plasmas." Plasma Physics and Controlled Fusion 55, no. 12 (November 28, 2013): 124016. http://dx.doi.org/10.1088/0741-3335/55/12/124016.

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16

Orlando, Elena, and Andrew Strong. "Cosmic rays: interstellar gamma-ray and radio emission." Nuclear Physics B - Proceedings Supplements 239-240 (June 2013): 64–69. http://dx.doi.org/10.1016/j.nuclphysbps.2013.05.010.

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17

Šimon, Vojtech. "NON-THERMAL EMISSION FROM CATACLYSMIC VARIABLES: IMPLICATIONS ON ASTROPARTICLE PHYSICS." Acta Polytechnica 53, A (December 18, 2013): 595–600. http://dx.doi.org/10.14311/ap.2013.53.0595.

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We review the lines of evidence that some cataclysmic variables (CVs) are the sources of non-thermal radiation. It was really observed in some dwarf novae in outburst, a novalike CV in the high state, an intermediate polar, polars, and classical novae (CNe) during outburst. The detection of this radiation suggests the presence of highly energetic particles in these CVs. The conditions for the observability of this emission depend on the state of activity, and the system parameters. We review the processes and conditions that lead to the production of this radiation in various spectral bands, from gamma-rays including TeV emission to radio. Synchrotron and cyclotron emissions suggest the presence of strong magnetic fields in CV. In some CVs, e.g. during some dwarf nova outbursts, the magnetic field generated in the accretion disk leads to the synchrotron jets radiating in radio. The propeller effect or a shock in the case of the magnetized white dwarf (WD) can lead to a strong acceleration of the particles that produce gamma-ray emission via pi0 decay; even Cherenkov radiation is possible. In addition, a gamma-ray production via pi0 decay was observed in the ejecta of an outburst of a symbiotic CN. Nuclear reactions during thermonuclear runaway in the outer layer of the WD undergoing CN outburst lead to the production of radioactive isotopes; their decay is the source of gamma-ray emission. The production of accelerated particles in CVs often has episodic character with a very small duty cycle; this makes their detection and establishing the relation of the behavior in various bands difficult.

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18

Biehl, D., D. Boncioli, A. Fedynitch, and W. Winter. "Cosmic ray and neutrino emission from gamma-ray bursts with a nuclear cascade." Astronomy & Astrophysics 611 (March 2018): A101. http://dx.doi.org/10.1051/0004-6361/201731337.

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Aim. We discuss neutrino and cosmic ray emission from gamma-ray bursts (GRBs) with the injection of nuclei, where we take into account that a nuclear cascade from photodisintegration can fully develop in the source. Our main objective is to test whether recent results from the IceCube and the Pierre Auger Observatory can be accommodated within the paradigm that GRBs are the sources of ultra-high-energy cosmic rays (UHECRs). Methods. We simulate this scenario in a combined source-propagation model. While our key results are obtained using an internal shock model of the source, we discuss how the secondary emission from a GRB shell can be interpreted in terms of other astrophysical models. Results. We demonstrate that the expected neutrino flux from GRBs weakly depends on the injection composition for the same injection spectra and luminosities, which implies that prompt neutrinos from GRBs can efficiently test the GRB-UHECR paradigm even if the UHECRs are nuclei. We show that the UHECR spectrum and composition, as measured by the Pierre Auger Observatory, can be self-consistently reproduced. In an attempt to describe the energy range including the ankle, we find tension with the IceCube bounds from the GRB stacking analyses. In an alternative scenario, where only the UHECRs beyond the ankle originate from GRBs, the requirement for a joint description of cosmic ray and neutrino observations favors lower luminosities, which does not correspond to the typical expectation from γ-ray observations.

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Минасянц, Геннадий, Gennady Minasyants, Тамара Минасянц, Tamara Minasyants, Владимир Томозов, and Vladimir Tomozov. "Features of development of sustained fluxes of high-energy gamma-ray emission at different stages of solar flares." Solar-Terrestrial Physics 5, no. 3 (September 30, 2019): 10–17. http://dx.doi.org/10.12737/stp-53201902.

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We have studied properties of sustained gamma fluxes having quantum energies of >100 MeV at different stages of flares with 1-min temporal resolution (Fermi/LAT). The most probable process of emergence of high-energy gamma-quanta during the impulsive phase of flares (6 events) has been confirmed. Acceleration of particles, produced by flare energy release (at dissipation of current sheet), occurs when they interact with a shock front of a coronal mass ejection (CME), which develops in the same active region at the same time. Nuclear interactions of accelerated protons (>500 MeV) with plasma ions lead further to the emergence of high-energy gamma-quanta. We have established that the interaction between a flare flux and a high-speed CME during the flare impulsive phase occurs within fairly limited periods — from 2 to 16 min. In the events considered, we have found a direct connection between maximum gamma flux F max (γ > 100 MeV) and CME velocity. High maximum values of gamma fluxes are typical of the flare impulsive phase: 3.5·10⁻⁴ cm⁻²s⁻¹ ≤ F max (γ > 100 MeV) ≤ 1.3·10⁻² cm⁻² s⁻¹. At the same time, the value F max (γ > 100 MeV) = 0.013 cm⁻²s⁻¹ was the highest for the events observed by Fermi/LAT from 2008 to 2017. During the development of CMEs moving with a supersonic speed, shock waves are formed which are the major power source of accelerated particles during the main phase of gradual flares. In some cases, however, the impact of shock waves on particle acceleration is the greatest in the short impulsive phase. To reveal parameters most effectively influencing the generation of high-energy gamma-ray emission, we have compared 17 flare events. The most significant parameter proved to be the time interval of joint action of flare process and CME shocks. We have established that during simultaneous development of flare process and CME attendant on the flare, the most efficient particle acceleration occurs which gives rise to maximum fluxes of high-energy gamma-quanta.

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de Menezes, Raniere, Rodrigo Nemmen, Justin D. Finke, Ivan Almeida, and Bindu Rani. "Gamma-ray observations of low-luminosity active galactic nuclei." Monthly Notices of the Royal Astronomical Society 492, no. 3 (January 16, 2020): 4120–30. http://dx.doi.org/10.1093/mnras/staa083.

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ABSTRACT The majority of the activity around nearby (z ≈ 0) supermassive black holes is found in low-luminosity active galactic nuclei (LLAGN), the most of them being classified as low-ionization nuclear emission regions. Although these sources are well studied from radio up to X-rays, they are poorly understood in γ-rays. In this work, we take advantage of the all sky-surveying capabilities of the Large Area Telescope on board Fermi Gamma-ray Space Telescope to study the whole Palomar sample of LLAGN in γ-rays. Precisely, the four radio-brightest LLAGN in the sample are identified as significant γ-ray emitters, all of which are recognized as powerful Fanaroff–Riley I galaxies. These results suggest that the presence of powerful radio jets is of substantial importance for observing a significant γ-ray counterpart even if these jets are misaligned with respect to the line of sight. We also find that most of the X-ray-brightest LLAGN do not have a significant γ-ray and strong radio emission, suggesting that the X-rays come mainly from the accretion flow in these cases. A detailed analysis of the spectral energy distributions (SEDs) of NGC 315 and NGC 4261, both detected in γ-rays, is provided where we make a detailed comparison between the predicted hadronic γ-ray emission from a radiatively inefficient accretion flow (RIAF) and the γ-ray emission from a leptonic jet-dominated synchrotron self-Compton (SSC) model. Both SEDs are better described by the SSC model, while the RIAF fails to explain the γ-ray observations.

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21

Berezhiani, Zurab, and Alessandro Drago. "Gamma ray bursts via emission of axion-like particles." Physics Letters B 473, no. 3-4 (February 2000): 281–90. http://dx.doi.org/10.1016/s0370-2693(99)01449-5.

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Asano, Katsuaki. "Cooling of Accelerated Nucleons and Neutrino Emission in Gamma‐Ray Bursts." Astrophysical Journal 623, no. 2 (April 20, 2005): 967–72. http://dx.doi.org/10.1086/428876.

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23

Janiuk, Agnieszka, Szymon Charzynski, and Michal Bejger. "On the gamma-ray burst – gravitational wave association in GW150914." Proceedings of the International Astronomical Union 12, S324 (September 2016): 291–94. http://dx.doi.org/10.1017/s174392131700223x.

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AbstractHyperaccreting disks around black holes are the engines that drive outflows and jets in gamma ray bursts (GRBs). The torus formed after the core collapse or a compact binary merger is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrinos rather than photon emission. Hyperaccretion powers the ultra-relativistic jets, where the GRB prompt emission originates. The neutrons produced in the disk and also in the outflowing material are necessary for the production of heavier nuclei. We discuss here the observable consequences of nucleosynthesis and we also apply the scenario of hyperaccretion to the gravitational wave source, GW150914. Temporal coincidence reported by the Fermi satellite suggested that the black hole merger might be accompanied with a GRB. We propose that a collapsing massive star and a black hole in a close binary could lead to such event. Gravitational wave emission due to the merger of collapsed core and the companion black hole might then coincide with a weak GRB.

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24

Diehl, Roland. "Gamma-ray observations and massive stars." Symposium - International Astronomical Union 193 (1999): 205–17. http://dx.doi.org/10.1017/s0074180900205317.

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Gamma-rays from astrophysical sources testify energetic processes such as nucleosynthesis and cosmic ray collisions. Gamma-rays are observable from throughout the Galaxy, unattenuated by interstellar matter, provided their intensity exceeds the current instrumental sensitivity level (∼ 10−5ph cm−2s−1 at 1 MeV). Massive stars are at the origin of relevant sources: The all-sky image in the 1.809 MeV γ-ray line from radioactive 26Al traces nucleosynthesis throughout the Galaxy. The structure of this emission along the plane of the Galaxy suggests massive stars as dominating sources of this radioactivity. Discrimination of the contribution from core collapse supernova against that from WR-wind ejected hydrostatic nucleosynthesis products may be obtained from 60Fe γ-ray line observations, or from spatial-profile consequences of the metallicity dependence of 26Al production in theories for both source sites. As a single source, the nearest WR star in the γ2 Vel system is found to eject less 26Al into interstellar space than current theories predict. However, a more adequate comparison must be based on a time-dependent 26Al light-curve of the system. Furthermore, continuum γ-ray production in WR binaries through wind-wind interaction, and constraints on the low-energy cosmic ray origin in WR winds through characteristic nuclear deexcitation line studies are targets of research. Studies stimulated by COMPTEL'S 3–7 MeV excess report from the Orion region indicate that the γ-ray line measurements could separate the origins from supernova ejecta and wind material. The COMPTEL Orion result is now attributed chiefly to an instrumental artifact, and has been withdrawn. Nevertheless, the search for MeV emission from massive star clusters, as well as from interacting binaries such as WR 140, promises a unique test of particle acceleration scenarios related to the source mechanism for cosmic ray production.

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25

Hurley, Kevin. "Cosmic Gamma-Ray Bursts: The Big Picture." International Astronomical Union Colloquium 192 (2005): 433–39. http://dx.doi.org/10.1017/s0252921100009519.

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SummaryA “typical” GRB occurs in a star-forming region of a galaxy at a redshift z~1. In currently popular models, it is caused by the collapse of a massive star which has exhausted its nuclear fuel supply. The star collapses to a black hole threaded by a strong magnetic field, and possibly fed by an accretion torus. Through a variety of processes, electrons are accelerated and gamma-rays, X-rays, optical light, and radio emission ensue, with durations from seconds to years. In this talk, I will review the general observational properties of bursts, their afterglows and host galaxies, and some of the open questions about them.

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Verburg, Joost M., Helen A. Shih, and Joao Seco. "Simulation of prompt gamma-ray emission during proton radiotherapy." Physics in Medicine and Biology 57, no. 17 (August 3, 2012): 5459–72. http://dx.doi.org/10.1088/0031-9155/57/17/5459.

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27

Peplow, Douglas E. "Specific Gamma-Ray Dose Constants with Current Emission Data." Health Physics 118, no. 4 (April 2020): 402–16. http://dx.doi.org/10.1097/hp.0000000000001136.

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RAZZAQUE, SOEBUR, PETER MÉSZÁROS, and BING ZHANG. "GEV TO PEV ENERGY PHOTON INTERACTIONS IN GAMMA-RAY BURST FIREBALLS AND SURROUNDINGS." International Journal of Modern Physics A 20, no. 14 (June 10, 2005): 3163–66. http://dx.doi.org/10.1142/s0217751x05026030.

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Shock acceleration mechanism in gamma-ray bursts may produce photons up to a few PeV energy. Photons above 10-100 GeV and below a PeV energy are trapped inside the fireball due to a high opacity of electron-positron pair production with other photons. High energy photons escaping the fireball may interact with cosmic background radiation and provide delayed gamma-ray emission detectable by GLAST. Detection of the prompt and delayed emission may provide useful constraints on the gamma-ray burst model and also on the inter-galactic magnetic field.

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Armstrong, T. A., R. Bishop, V. Harris, R. A. Lewis, E. Minor, and G. A. Smith. "Nuclear gamma-ray emission from antiproton annihilation at rest in uranium." Zeitschrift f�r Physik A Atomic Nuclei 331, no. 4 (December 1988): 519–20. http://dx.doi.org/10.1007/bf01291910.

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30

Karbach, H., H. Spiering, and P. Gütlich. "Gamma-X-ray coincidence Mössbauer emission spectroscopy on57Co/CoO." Hyperfine Interactions 93, no. 1 (December 1994): 1579–83. http://dx.doi.org/10.1007/bf02072912.

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STERN, B. E., and J. POUTANEN. "GAMMA-RAY EMISSION OF RELATIVISTIC JETS AS A SUPERCRITICAL PROCESS." International Journal of Modern Physics D 17, no. 09 (September 2008): 1611–17. http://dx.doi.org/10.1142/s0218271808013212.

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Supercriticality of the same kind as that in a nuclear pile can take place in high-energy astrophysical objects producing a number of impressive effects. For example, it could cause an explosive release of the energy of a cloud of ultrarelativistic protons into radiation. More certainly, supercriticality should be responsible for energy dissipation of very energetic relativistic fluids such as ultrarelativistic shocks in gamma-ray bursts and jets in active galactic nuclei (AGNs). In this case, the photon breeding process operates. It is a kind of converter mechanism with the high-energy photons and e+e- pairs converting into each other via pair production and inverse Compton scattering. Under certain conditions, which should be satisfied in powerful AGNs, the photon breeding mechanism becomes supercritical: the high-energy photons breed exponentially until their feedback on the fluid changes its velocity pattern. Then the system comes to a self-adjusting near-critical steady state. Monte-Carlo simulations with detailed treatment of particle propagation and interactions demonstrate that a jet with a Lorentz factor Γ ≈ 20 can radiate away up to a half of its total energy, and for Γ = 40 the radiation efficiency can be up to 80 per cent. Outer layers of the jet decelerate down to a moderate Lorentz factor 2–4, while the spine of the jet has a final Lorentz factor in the range 10–20 independent of the initial Γ. Such sharp deceleration under the impact of radiation must cause a number of interesting phenomena such as formation of internal shocks and an early generation of turbulence.

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32

Yoshimori, M., K. Suga, K. Morimoto, T. Hiraoka, J. Sato, K. Kawabata, and K. Ohki. "Gamma-Ray Spectral Observations with Yohkoh." International Astronomical Union Colloquium 142 (1994): 639–43. http://dx.doi.org/10.1017/s0252921100077915.

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AbstractWe present gamma-ray observations of the 1991 October 27, November 15, and December 3 flares with the Yohkoh gamma-ray and hard X-ray spectrometers. The October 27 flare (X6.1 /3B) shows significant gamma-ray line emission, and the temporal evolution of the gamma-ray line-to-bremsstrahlung flux ratio indicates that protons and electrons were complicatedly accelerated during flare. The December 3 flare (X2.0/2B) shows a strong bremsstrahlung continuum extending to 10 MeV and indicates that electrons were preferentially accelerated to 10 MeV. A line feature at 420 keV was observed from the November 15 flare (X1.0/3B). This is most likely due to a compound of redshifted nuclear deexcitation lines of Be (429 keV) and Li (478 keV) resulting from He-He reactions. The spectral feature indicates that the accelerated He nuclei suffer strong pitch-angle scattering in the corona and form a downward-peaked distribution. Furthermore, the November 15 flare exhibits evidence of positron annihilation line at 511 keV. The positron production processes and the electron density of the annihilation region are discussed on the basis of the temporal characteristics of 511 keV line emission.Subject headings: line: identification — Sun: flares — Sun: X-rays, gamma-rays

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Matsue, H., and C. Yonezawa. "The recommended k0-factors for neutron-induced prompt gamma-ray analysis and the prompt gamma-ray emission probabilities." Journal of Radioanalytical and Nuclear Chemistry 262, no. 1 (2004): 49–55. http://dx.doi.org/10.1023/b:jrnc.0000040853.53889.34.

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34

Jarvis, O. N., J. M. Adams, P. J. A. Howarth, F. B. Marcus, E. Righi, G. J. Sadler, D. F. H. Start, P. Van Belle, C. D. Warrick, and N. Watkins. "Gamma ray emission profile measurements from JET ICRF-heated discharges." Nuclear Fusion 36, no. 11 (November 1996): 1513–30. http://dx.doi.org/10.1088/0029-5515/36/11/i06.

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35

Williams, Mark B., Mitali J. More, Deepa Narayanan, Stan Majewski, Andrew G. Weisenberger, Randal Wojcik, Martin Stanton, Walter Phillips, and Alex Stewart. "Combined Structural and Functional Imaging of the Breast." Technology in Cancer Research & Treatment 1, no. 1 (February 2002): 39–42. http://dx.doi.org/10.1177/153303460200100105.

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Scintimammography, or single gamma nuclear imaging of the breast, has shown promise as a way of characterizing certain biological properties of suspicious breast masses. Conventional scintimammography, performed using large clinical gamma cameras and prone patient positioning suffers from several drawbacks including poor sensitivity for small (< 1 cm) lesions and no reliable method for correlating scintigraphic findings with those of other imaging modalities. We are developing a system designed to overcome some of these problems. The system combines x-ray mammography with scintimammography on a common gantry. The x-ray and gamma ray images are obtained in quick succession, with the breast in a common configuration under mild compression. A digital x-ray detector is used, permitting rapid assessment of lesion location prior to gamma imaging, and enabling fusion of the x-ray transmission and gamma emission information in a single digital image. In a pilot clinical diagnostic study, the system has demonstrated high pathology-proven accuracy in differentiating benign and malignant masses.

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Casanova, Sabrina. "Gamma-ray emission from molecular clouds: A probe of cosmic-ray origin and propagation." Progress in Particle and Nuclear Physics 66, no. 3 (July 2011): 681–85. http://dx.doi.org/10.1016/j.ppnp.2011.01.029.

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37

Terada, Kazushi, Shoji Nakamura, Taro Nakao, Atsushi Kimura, Osamu Iwamoto, Hideo Harada, Koichi Takamiya, and Jun-ichi Hori. "Measurements of gamma-ray emission probabilities of 241, 243Am and 239Np." Journal of Nuclear Science and Technology 53, no. 11 (April 26, 2016): 1881–88. http://dx.doi.org/10.1080/00223131.2016.1174167.

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38

Chi, X., M. R. Issa, K. M. Richardson, J. Szabelski, J. Wdowczyk, and A. W. Wolfendale. "The inverse Compton contribution to medium-latitude Galactic gamma-ray emission." Journal of Physics G: Nuclear and Particle Physics 15, no. 9 (September 1, 1989): 1495–507. http://dx.doi.org/10.1088/0954-3899/15/9/018.

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39

BÖTTCHER, MARKUS, and PARISA ROUSTAZADEH. "VHE GAMMA-RAY INDUCED PAIR CASCADES IN BLAZARS AND RADIO GALAXIES." International Journal of Modern Physics: Conference Series 08 (January 2012): 13–18. http://dx.doi.org/10.1142/s2010194512004357.

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Recent discoveries by VERITAS, H.E.S.S., and MAGIC indicate that very-high-energy (VHE) gamma-rays may be produced in all types of blazars, including radio-loud quasars. In the dense nuclear radiation fields (BLR, dust torus IR) in these objects, VHE gamma-rays may be efficiently absorbed and initiate Compton-supported pair cascades. We have developed a Monte-Carlo code following the full 3-dimensional development of pair cascades in AGN environments. We have shown that even very weak magnetic fields may lead to efficient quasi-isotropization of the cascade emission, escaping predominantly in MeV – GeV gamma-rays. We propose this as a potential contributor to the Fermi gamma-ray flux from several radio galaxies, and present model fits to the Fermi-detected radio galaxies NGC 1275 and Cen A.

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GIGLIETTO, N. "STATUS AND PERSPECTIVES OF GLAST GAMMA RAY EXPERIMENT." International Journal of Modern Physics A 20, no. 29 (November 20, 2005): 7009–11. http://dx.doi.org/10.1142/s0217751x05030703.

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GLAST, the Gamma-ray Large Area Telescope, is a satellite-based experiment able to measure the cosmic gamma-ray flux in the energy range between 20 MeV and 300 GeV or above. The sensitivity is more than 30 times respect to EGRET and the good spatial and time resolution over a large field of view let us to cover a large variety of high energy phenomena. In particular GLAST will be able to study both diffuse emission and point-like gamma ray sources, including active galactic nuclei, gamma ray bursts, pulsars and supernova remnants. In addition, the potentialities of GLAST to explore rare or exotic phenomena like supersymmetric dark matter annihilations will be shown. The present knowledge of the science opportunities that the GLAST experiment can explore will be completed with the detector description and the current status of the experiment.

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41

Belanger-Champagne, Camille, Pauli Peura, Paula Eerola, Tapani Honkamaa, Timothy White, Mikhail Mayorov, and Peter Dendooven. "Effect of Gamma-Ray Energy on Image Quality in Passive Gamma Emission Tomography of Spent Nuclear Fuel." IEEE Transactions on Nuclear Science 66, no. 1 (January 2019): 487–96. http://dx.doi.org/10.1109/tns.2018.2881138.

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42

Nocente, M., J. Källne, M. Salewski, M. Tardocchi, and G. Gorini. "Gamma-ray emission spectrum from thermonuclear fusion reactions without intrinsic broadening." Nuclear Fusion 55, no. 12 (October 30, 2015): 123009. http://dx.doi.org/10.1088/0029-5515/55/12/123009.

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43

Lin, W. J., and G. Harbottle. "Gamma ray emission intensities of226Ra in equilibrium with its daughter products." Journal of Radioanalytical and Nuclear Chemistry Letters 153, no. 2 (February 1991): 137–49. http://dx.doi.org/10.1007/bf02164874.

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44

Diehl, Roland. "Measuring Cosmic Elements with Gamma-Ray Telescopes." Publications of the Astronomical Society of Australia 26, no. 3 (2009): 359–64. http://dx.doi.org/10.1071/as08074.

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AbstractGamma-ray telescopes are capable of measuring radioactive trace isotopes from cosmic nucleosynthesis events. Such measurements address new isotope production rather directly for a few key isotopes such as 44Ti, 26Al, 60Fe, and 56Ni, as well as positrons from the β+-decay variety. Experiments of the past decades have now established an astronomy with γ-ray lines, which is an important part of the study of nucleosynthesis environments in cosmic sources. For massive stars and supernovae, important constraints have been set: Co isotope decays in SN1987A directly demonstrated the synthesis of new isotopes in core-collapse supernovae, 44Ti from the 340-year-old Cas A supernova supports the concept of α-rich freeze-out, but results in interesting puzzles pursued by theoretical studies and future experiments. 26Al and 60Fe has been measured from superimposed nucleosynthesis within our Galaxy, and sets constraints on massive-star interior structure through its intensity ratio of ∼15%. The 26Al γ-ray line is now seen to trace current star formation and even the kinematics of interstellar medium throughout the Galaxy. Positron annihilation emission from nucleosynthesis throughout the plane of our Galaxy appears to be mainly from 26Al and other supernova radioactivity, but the striking brightness of the Galaxy's bulge region in positron annihilation γ-rays presents a puzzle involving several astrophysics issues beyond nuclear astrophysics. This paper focuses mainly on a discussion of 26Al and 60Fe from massive-star nucleosynthesis.

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Nakamura, Shoji, Kazushi Terada, Atsushi Kimura, Taro Nakao, Osamu Iwamoto, Hideo Harada, Akihiro Uehara, Koichi Takamiya, and Toshiyuki Fujii. "Measurements of gamma-ray emission probabilities in the decay of americium-244g." Journal of Nuclear Science and Technology 56, no. 1 (November 5, 2018): 123–29. http://dx.doi.org/10.1080/00223131.2018.1539353.

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46

Kataoka, Jun, Yoshiaki Sofue, Yoshiyuki Inoue, Masahiro Akita, Shinya Nakashima, and Tomonori Totani. "X-Ray and Gamma-Ray Observations of the Fermi Bubbles and NPS/Loop I Structures." Galaxies 6, no. 1 (February 26, 2018): 27. http://dx.doi.org/10.3390/galaxies6010027.

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The Fermi bubbles were possibly created by large injections of energy into the Galactic Center (GC), either by an active galactic nucleus (AGN) or by nuclear starburst more than ~10 Myr ago. However, the origin of the diffuse gamma-ray emission associated with Loop I, a radio continuum loop spanning across 100° on the sky, is still being debated. The northern-most part of Loop I, known as the North Polar Spur (NPS), is the brightest arm and is even clearly visible in the ROSAT X-ray sky map. In this paper, we present a comprehensive review on the X-ray observations of the Fermi bubbles and their possible association with the NPS and Loop I structures. Using uniform analysis of archival Suzaku and Swift data, we show that X-ray plasma with kT~0.3 keV and low metal abundance (Z~0.2 Z◉) is ubiquitous in both the bubbles and Loop I and is naturally interpreted as weakly shock-heated Galactic halo gas. However, the observed asymmetry of the X-ray-emitting gas above and below the GC has still not been resolved; it cannot be fully explained by the inclination of the axis of the Fermi bubbles to the Galactic disk normal. We argue that the NPS and Loop I may be asymmetric remnants of a large explosion that occurred before the event that created the Fermi bubbles, and that the soft gamma-ray emission from Loop I may be due to either π0 decay of accelerated protons or electron bremsstrahlung.

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Nagai, Tomoyuki, and Vladimir Vassiliev. "Gamma-ray Observation of Nearby Starburst Galaxy IC342." International Journal of Modern Physics A 20, no. 14 (June 10, 2005): 3167–69. http://dx.doi.org/10.1142/s0217751x05026042.

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Regions with high star formation rates (SFR) in starburst galaxies (SBGs) are frequently accompanied by high density clouds of interstellar matter (ISM). This may create nearly perfect conditions for generating diffuse gamma-ray radiation as high energy cosmic rays accelerated in supernovae explosions of massive progenitor stars interact with the ambient protons. If the current paradigm that supernovae are the origin sites of high energy cosmic rays is valid, then the star forming regions rich in supernovae may become the laboratories to test and study this phenomenon. The gamma-ray luminosity of these extragalactic objects is suppressed by a large distance factor compared to supernovae in our own galaxy. However, flux estimates indicate that if star bursting regions have a proper combination of critical parameters (intersteller medium density, age, size, supernova rate, magnetic field strength) the cumulative enhancement of the gamma-ray luminosity resulting from multiple explosions of supernovae into dense ISM may generate an observable flux for nearby SBGs such as M82, IC342. A search for TeV gamma-ray emission from IC342 was conducted with the Whipple 10m gamma-ray telescope from September 2002 to March 2004.

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HIROTANI, KOUICHI. "HIGH-ENERGY EMISSION FROM PULSAR MAGNETOSPHERES." Modern Physics Letters A 21, no. 17 (June 7, 2006): 1319–37. http://dx.doi.org/10.1142/s0217732306020846.

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A synthesis of the present knowledge on gamma-ray emission from the magnetosphere of a rapidly rotating neutron star is presented, focusing on the electrodynamics of particle accelerators. The combined curvature, synchrotron, and inverse-Compton emission from ultra-relativistic positrons and electrons, which are created by two-photon and/or one-photon pair creation processes, or emitted from the neutron-star surface, provide us with essential information on the properties of the accelerator — electric potential drop along the magnetic field lines. A new accelerator model, which is a mixture of traditional inner gap and outer gap models, is also proposed, by solving the Poisson equation for the electrostatic potential together with the Boltzmann equations for particles and gamma-rays in the two-dimensional configuration and two-dimensional momentum spaces.

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Kondev, F. G., I. Ahmad, J. P. Greene, A. L. Nichols, and M. A. Kellett. "Measurements of absolute gamma-ray emission probabilities in the decay of 233Pa." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 652, no. 1 (October 2011): 654–56. http://dx.doi.org/10.1016/j.nima.2011.01.147.

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Nerush, E. N., and I. Y. Kostyukov. "Laser-driven hole boring and gamma-ray emission in high-density plasmas." Plasma Physics and Controlled Fusion 57, no. 3 (February 16, 2015): 035007. http://dx.doi.org/10.1088/0741-3335/57/3/035007.

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