High-energy Gamma-ray Production Research Articles

Simulating the Galactic multi-messenger emissions with HERMES

Context. The study of nonthermal processes such as synchrotron emission, inverse Compton scattering, bremsstrahlung, and pion production is crucial to understanding the properties of the Galactic cosmic-ray population, to shed light on their origin and confinement mechanisms, and to assess the significance of exotic signals possibly associated to new physics. Aims. We present a public code called HERMES which is designed generate sky maps associated to a variety of multi-messenger and multi-wavelength radiative processes, spanning from the radio domain all the way up to high-energy gamma-ray and neutrino production. Methods. We describe the physical processes under consideration, the code concept and structure, and the user interface, with particular focus on the python-based interactive mode. In particular, present the modular and flexible design that allows the user to easily extend the numerical package according to their needs. Results. In order to demonstrate the capabilities of the code, we describe the details of a comprehensive set of sky maps and spectra associated to all physical processes included in the code. We comment in particular on the radio, gamma-ray, and neutrino maps, and mention the possibility of studying signals stemming from dark matter annihilation. Conclusions. HERMES can be successfully applied to constrain the properties of the Galactic cosmic-ray population, improve our understanding of the diffuse Galactic radio, gamma-ray, and neutrino emission, and search for signals associated to particle dark matter annihilation or decay.

Observation of Photons above 300 TeV Associated with a High-energy Neutrino from the Cygnus Region

Abstract Galactic sites of acceleration of cosmic rays to energies of order 1015 eV and higher, dubbed PeVatrons, reveal themselves by recently discovered gamma radiation of energies above 100 TeV. However, joint gamma-ray and neutrino production, which marks unambiguously cosmic-ray interactions with ambient matter and radiation, was not observed until now. In 2020 November, the IceCube neutrino observatory reported an ∼150 TeV neutrino event from the direction of one of the most promising Galactic PeVatrons, the Cygnus Cocoon. Here we report on the observation of a 3.1σ (post-trial) excess of atmospheric air showers from the same direction, observed by the Carpet–2 experiment and consistent with a few months flare in photons above 300 TeV, in temporal coincidence with the neutrino event. The fluence of the gamma-ray flare is of the same order as that expected from the neutrino observation, assuming the standard mechanism of neutrino production. This is the first evidence for the joint production of high-energy neutrinos and gamma-rays in a Galactic source.

High-energy Neutrino and Gamma-Ray Emission from Tidal Disruption Events

Abstract Tidal disruption events (TDE) have been considered as cosmic-ray and neutrino sources for a decade. We suggest two classes of new scenarios for high-energy multi-messenger emission from TDEs that do not have to harbor powerful jets. First, we investigate high-energy neutrino and gamma-ray production in the core region of a supermassive black hole. In particular, we show that ∼1–100 TeV neutrinos and MeV gamma rays can efficiently be produced in hot coronae around an accretion disk. We also study the consequences of particle acceleration in radiatively inefficient accretion flows (RIAFs). Second, we consider possible cosmic-ray acceleration by sub-relativistic disk-driven winds or interactions between tidal streams, and show that subsequent hadronuclear and photohadronic interactions inside the TDE debris lead to GeV-PeV neutrinos and sub-GeV cascade gamma rays. We demonstrate that these models should be accompanied by soft gamma rays or hard X-rays as well as optical/UV emission, which can be used for future observational tests. Although this work aims to present models of non-jetted high-energy emission, we discuss the implications of the TDE AT2019dsg that might coincide with the high-energy neutrino IceCube-191001A, by considering the corona, RIAF, hidden sub-relativistic wind, and hidden jet models. It is not yet possible to be conclusive about their physical association and the expected number of neutrinos is typically much less than unity. We find that the most optimistic cases of the corona and hidden wind models could be consistent with the observation of IceCube-191001A, whereas jet models are unlikely to explain the multi-messenger observations.

Upscattered Cocoon Emission in Short Gamma-Ray Bursts as High-energy Gamma-Ray Counterparts to Gravitational Waves

Abstract We investigate prolonged engine activities of short gamma-ray bursts (SGRBs), such as extended and/or plateau emissions, as high-energy gamma-ray counterparts to gravitational waves (GWs). Binary neutron-star mergers lead to relativistic jets and merger ejecta with r-process nucleosynthesis, which are observed as SGRBs and kilonovae/macronovae, respectively. Long-term relativistic jets may be launched by the merger remnant as hinted in X-ray light curves of some SGRBs. The prolonged jets may dissipate their kinetic energy within the radius of the cocoon formed by the jet–ejecta interaction. Then the cocoon supplies seed photons to nonthermal electrons accelerated at the dissipation region, causing high-energy gamma-ray production through the inverse Compton scattering process. We numerically calculate high-energy gamma-ray spectra in such a system using a one-zone and steady-state approximation, and show that GeV–TeV gamma-rays are produced with a duration of 102–105 s. They can be detected by Fermi/LAT or CTA as gamma-ray counterparts to GWs.

Tabletop laser-driven gamma-ray source with nanostructured double-layer target

Laser-driven gamma-ray source potentially offers a compact, cost-effective, ultra-short, and ultra-bright alternative to conventional gamma-ray sources based on large-scale particle accelerators. Based on the laser-driven approach, we use multidimensional particle-in-cell simulations to demonstrate that a nanostructured double-layer target, which consists of a nanostructured foam coated on top of a metal substrate, can absorb laser energy into high-energy electrons in the nanostructured foam, and then efficiently convert it into copious gamma photons via the nonlinear Compton scattering process enabled by the solid-density substrate, which acts as a plasma mirror to reflect the laser pulse. The effects of different nanostructures in the foam target and the oblique laser incidence are presented. It is shown that the conversion efficiency of gamma photons increases when the size of nanoparticles decreases or the filling factor of nanoparticles increases in nanostructured foam target, but decreases when the laser incidence angle increases. At realistic conditions with nanostructured foam and non-normal incidence, the double-layer target still exhibits an unprecedentedly high conversion efficiency in high-energy gamma-ray production due to the laser reflection by the plasma mirror, which can be two and even three orders of magnitude higher than that of the single-layer target without the substrate using currently available lasers with intensity of 1021 .

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

Abstract We present new theoretical modeling to predict the luminosity and spectrum of gamma-ray and neutrino emission of a star-forming galaxy, from the star formation rate (ψ), gas mass (Mgas), stellar mass, and disk size, taking into account production, propagation, and interactions of cosmic rays. The model reproduces the observed gamma-ray luminosities of nearby galaxies detected by Fermi better than the simple power-law models as a function of ψ or ψMgas. This model is then used to predict the cosmic background flux of gamma-rays and neutrinos from star-forming galaxies, by using a semi-analytical model of cosmological galaxy formation that reproduces many observed quantities of local and high-redshift galaxies. Calibration of the model using gamma-ray luminosities of nearby galaxies allows us to make a more reliable prediction than previous studies. In our baseline model, star-forming galaxies produce about 20% of the isotropic gamma-ray background unresolved by Fermi, and only 0.5% of IceCube neutrinos. Even with an extreme model assuming a hard injection cosmic-ray spectral index of 2.0 for all galaxies, at most 22% of IceCube neutrinos can be accounted for. These results indicate that it is difficult to explain most of the IceCube neutrinos by star-forming galaxies, without violating the gamma-ray constraints from nearby galaxies.

Scenarios for Ultrafast Gamma-Ray Variability in AGN

Abstract We analyze three scenarios to address the challenge of ultrafast gamma-ray variability reported from active galactic nuclei. We focus on the energy requirements imposed by these scenarios: (i) external cloud in the jet, (ii) relativistic blob propagating through the jet material, and (iii) production of high-energy gamma-rays in the magnetosphere gaps. We show that while the first two scenarios are not constrained by the flare luminosity, there is a robust upper limit on the luminosity of flares generated in the black hole magnetosphere. This limit depends weakly on the mass of the central black hole and is determined by the accretion disk magnetization, viewing angle, and the pair multiplicity. For the most favorable values of these parameters, the luminosity for 5-minute flares is limited by , which excludes a black hole magnetosphere origin of the flare detected from IC 310. In the scopes of scenarios (i) and (ii), the jet power, which is required to explain the IC 310 flare, exceeds the jet power estimated based on the radio data. To resolve this discrepancy in the framework of scenario (ii), it is sufficient to assume that the relativistic blobs are not distributed isotropically in the jet reference frame. A realization of scenario (i) demands that the jet power during the flare exceeds by a factor 102 the power of the radio jet relevant to a timescale of 108 years.

New insights into the global composition of the lunar surface from high-energy gamma rays measured by Lunar Prospector

[1] An analysis of the lunar gamma-ray spectrum as measured by the Lunar Prospector Gamma-Ray Spectrometer has revealed that 8–8.9 MeV gamma rays contain information about the elemental composition of near-surface materials. These high-energy gamma rays are found to be primarily sensitive to the total Fe and Mg content of the surface, although other elements also contribute. This information has been used to identify several regions with unique compositions, including the Hertzsprung and Orientale basins. A method for deriving global Mg abundances from high-energy gamma-ray measurements is presented. The physical mechanism for high-energy gamma-ray production is proposed to be radiation produced during the decay of galactic cosmic ray produced pions within the lunar surface. Laboratory measurements of pion production cross sections are found to be consistent with the empirically derived relationship between the lunar Fe, Mg, and Ti abundances and the measured high-energy gamma-ray count rates.

High-energy gamma-ray emission from the inner jet of LS I +61 303: the hadronic contribution revisited

LS I +61 303 has been detected by the Cherenkov telescope MAGIC at very high energies, presenting a variable flux along the orbital motion with a maximum clearly separated from the periastron passage. In the light of the new observational constraints, we revisit the discussion of the production of high-energy gamma rays from particle interactions in the inner jet of this system. The hadronic contribution could represent a major fraction of the TeV emission detected from this source. The spectral energy distribution resulting from pp interactions is recalculated. Opacity effects introduced by the photon fields of the primary star and the stellar decretion disk are shown to be essential in shaping the high-energy gamma-ray light curve at energies close to 200 GeV. We also present results of Monte Carlo simulations of the electromagnetic cascades developed very close to the periastron passage. We conclude that a hadronic microquasar model for the gamma-ray emission in LS I +61 303 can reproduce the main features of its observed high-energy γ-ray flux.

Neutrinos from Relativistic Outflows of Fast Spinning Magnetars

AbstractPulsars may be born with a short rotation period of milliseconds with the magnetic field amplified through dynamo processes up to ∼1015–1016 G. Such millisecond magnetars spin down rapidly, emitting bursts of high-energy neutrinos and gamma rays. Specifically, acceleration of ions in both the polar gap (as in a normal pulsar) and the relativistic magnetar wind is considered. In both cases ions can be accelerated to ultra-high energies and these energetic ions can lead to production of high-energy neutrinos and gamma rays through interaction with thermal radiation from the hot neutron star or the heated inner boundary region of the stellar envelope as the result of the deposition of energy by the magnetar wind. The detectability of the neutrino flux by a kilometre-scale neutrino detector such as the planned IceCube neutrino observatory is discussed.

The proton synchrotron model of TeV gamma ray bursts and their detectability by AMANDA/ICECUBE type detectors

The detectability of a possible “high” energy (>100 GeV) component of gamma ray bursts (GRBs) using AMANDA/ICECUBE large area muon detectors is examined within the context of a specific model of such high energy gamma ray production within GRBs, namely, the proton-synchrotron model, which requires protons to be accelerated to ultrahigh energies ≳10 20 eV within GRBs. In this model, the high energy component is distinct from, but may well be emitted in coincidence with, the usual “low” (keV–MeV) energy component observed by satellite-borne detectors. The AMANDA/ICECUBE detectors can detect TeV photons by detecting the secondary muons created by the TeV photons in the Earth’s atmosphere. We calculate the muon signal-to-noise ratio in these detectors due to TeV gamma rays from individual GRBs for various assumptions on their luminosity, distance (redshift), Lorentz gamma factor of the underlying fireball model, and various spectral characteristics of the GRBs, including the effect of the absorption of TeV photons within the GRB as well as in the intergalactic infrared radiation background. The intergalactic absorption effect essentially precludes detection of TeV photons in the AMANDA detector for reasonable values of the luminosity in the high energy component, but they may well be detectable in the proposed ICECUBE detector which may have an effective area for downward-going muons a factor of 100 larger than that in AMANDA. However, even in ICECUBE, only relatively close-by GRBs at redshifts <0.05 or so can be expected to be detectable with any reasonable degree of confidence. We discuss the requirement on the luminosity of the GRB in the high energy component for its detectability in ICECUBE.

Reaction dynamics and hot nuclei formation in the36Ar+98Moreaction at37AMeVstudied through light charged particle andγ-ray emission

Central and mid-central collisions which lead to the formation of a heavy residue in the 37A MeV ${}^{36}\mathrm{Ar}{+}^{98}$Mo reaction have been studied with the MEDEA multidetector array coupled to a Parallel Plate Avalanche Counter. The dependence of the high energy gamma ray and light charged particle production as a function of the linear momentum transferred to the fused system has been studied. The unique potentialities of the MEDEA detector have made it possible to follow the evolution of the reaction dynamics from the pre-equilibrium stage to the formation of a heavy compound nucleus. The analysis of the correlation between the most energetic photons and protons shows how both of them are mainly produced in the most energetic primary nucleon-nucleon collisions. The multiplicity of high energy ${(E}_{\ensuremath{\gamma}}&gt;30\mathrm{MeV})$ $\ensuremath{\gamma}$ rays has been found to increase with the linear momentum transfer, showing the dominance of two-body dissipation in the transfer mechanism and giving a tool to correlate the momentum transfer with the centrality of the collision. Light charged particle kinetic energy spectra show how in these collisions, compound systems with excitation energies of more than $3A\mathrm{MeV}$ and temperature up to 7 MeV are formed. The experimental findings are compared with Boltzmann-Nordheim-Vlasov calculations. A scenario is found where the nucleus-nucleus interaction starts with two-body nucleon-nucleon collisions in the overlap region of nuclear densities. These collisions give rise to the production of high energy nucleons and $\ensuremath{\gamma}$ rays, and play a fundamental role in the energy transfer from the relative motion to internal excitation of the quasiprojectile and the target.

Very High Energy Gamma Rays from Young Pulsars and Supernova Remnants in the Southern Hemisphere

Observations have been made with the University of Durham Mark 6 telescope of a number of southern hemisphere supernova remnants and young pulsars (Vela pulsar, PSR B1055-52, PSR J1105-6107, PSR J0537-6910, and PSR B0540-69). No very high energy gamma-ray emission, either steady or pulsed, has been detected from these objects. The implications of these results for theories of high-energy gamma-ray production in plerions and young pulsars are discussed.

Possible production of high-energy gamma rays from proton acceleration in the extragalactic radio source markarian 501

The active galaxy Markarian 501 was discovered with air-Cerenkov telescopes at photon energies of 10 tera-electron volts. Such high energies may indicate that the gamma rays from Markarian 501 are due to the acceleration of protons rather than electrons. Furthermore, the observed absence of gamma ray attenuation due to electron-positron pair production in collisions with cosmic infrared photons implies a limit of 2 to 4 nanowatts per square meter per steradian for the energy flux of an extragalactic infrared radiation background at a wavelength of 25 micrometers. This limit provides important clues about the epoch of galaxy formation.

Gamma-Ray Pulsars: Beaming Evolution, Statistics, and Unidentified EGRET Sources

We compute the variation of the beaming fraction with the efficiency of high energy gamma-ray production in the outer gap pulsar model of Romani and Yadigaroglu. This allows us to correct the fluxes observed for pulsars in the EGRET band and to derive a simple estimate of the variation of efficiency with age. Integration of this model over the population of young neutron stars gives the expected number of gamma-ray pulsars along with their distributions in age and distance. This model also shows that many of the unidentified EGRET plane sources should be pulsars, and predicts the gamma-ray fluxes of known radio pulsars. The contribution of unresolved pulsars to the background flux in the EGRET band is found to be about 5 %. For an animation of our pulsar model see this http URL .

High energy particles from active galactic nuclei

In this paper, I summarize the results of recent work by myself and colleagues on the production of high energy neutrinos, gamma-rays and cosmic rays in radio-quiet active galactic nuclei (AGN) or in the central regions of radio-loud AGN. In this work, we used a model in which acceleration of protons takes place at a shock in an accretion flow onto a supermassive black hole, and follow the cascade that results from interactions of the accelerated protons in the AGN environment. Our results are used to estimate the diffuse high energy neutrino, gamma-ray and cosmic ray intensity due to AGN. I discuss our results in the context of existing data and future experiments. Finally, I describe a new self-consistent calculation by Mastichiadis and Kirk.

On the new theory of ultra-high-energy gamma-ray production in Cygnus X-3

view Abstract Citations (4) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the New Theory of Ultra--High-Energy Gamma-Ray Production in Cygnus X-3 Mitra, Abhas Abstract We develope here a model for ultra-high-energy gamma-ray production in Cygnus X-3 based on our earlier suggestion that in the presence of a strong soft X-ray field around the putative neutron star, the most dominant mechanism for cooling of the ultra-high-energy (UHE) protons should be the photomeson process which, in turn, should give rise to Very-High-Energy (VHE) - UHE gamma-rays. We envisage the spherical accretion shock around the neutron star to be specially conducive to acceleration of protons following supposed minor enhanced mass accretion and concomitant recession of the magnetopause due to enhanced radiation pressure at suitable orbital phases. It is also assumed that the accretion shock is quasi-perpendicular to enable fastest possible acceleration of protons. Relatively lower energy protons remain trapped in the magnetosphere yielding relatively lower energy pi0s and then photons. On the other hand, the highest energy protons stream out of the magnetopause (to reach a region of much lower magnetic field) and give rise to UHE gamma-rays. However, in most of the realistic cases, there may be a significant reduction of the high-energy photon luminosity because of magnetic degradation of the photons. Publication: The Astrophysical Journal Pub Date: April 1994 DOI: 10.1086/174022 Bibcode: 1994ApJ...425..782M Keywords: Gamma Rays; High Energy Interactions; Neutron Stars; Particle Acceleration; Particle Production; Gamma Ray Observatory; Hadrons; Magnetopause; Pions; Shock Wave Propagation; Stellar Mass Accretion; X Ray Binaries; Astrophysics; ACCELERATION OF PARTICLES; GAMMA RAYS: THEORY; RADIATION MECHANISMS: NONTHERMAL; STARS: INDIVIDUAL CONSTELLATION NAME: CYGNUS X-3 full text sources ADS | data products SIMBAD (1)

High energy gamma ray production in proton-induced reactions at 104, 145, and 195 MeV.

Energy spectra and angular distributions have been measured for high energy gamma rays ({ital E}{sub {gamma}}{ge}20 MeV) from proton-nucleus reactions at 104, 145, and 195 MeV on targets of C, Zn, and Pb. Gamma rays were observed with energies up to 170 MeV. The spectra showed differences from the typical exponential shape that is observed in gamma ray production from heavy-ion reactions. The angular distribution of the gamma ray is forward peaked in the laboratory, which is consistent with emission from a moving source. A comparison is made with previous measurements at 72, 140, 168, and 200 MeV. The experimental evidence indicates that first-chance incoherent proton-neutron bremsstrahlung is the main production mechanism.

High-energy gamma-ray emission from pion decay in a solar flare magnetic loop

view Abstract Citations (51) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Energy Gamma-Ray Emission from Pion Decay in a Solar Flare Magnetic Loop Mandzhavidze, Natalie ; Ramaty, Reuven Abstract The production of high-energy gamma rays resulting from pion decay in a solar flare magnetic loop is investigated. Magnetic mirroring, MHD pitch-angle scattering, and all of the relevant loss processes and photon production mechanisms are taken into account. The transport of both the primary ions and the secondary positrons resulting from the decay of the positive pions, as well as the transport of the produced gamma-ray emission are considered. The distributions of the gamma rays as a function of atmospheric depth, time, emission angle, and photon energy are calculated and the dependence of these distributions on the model parameters are studied. The obtained angular distributions are not sufficiently anisotropic to account for the observed limb brightening of the greater than 10 MeV flare emission, indicating that the bulk of this emission is bremsstrahlung from primary electrons. Publication: The Astrophysical Journal Pub Date: April 1992 DOI: 10.1086/171247 Bibcode: 1992ApJ...389..739M Keywords: Gamma Rays; Magnetohydrodynamics; Pions; Radioactive Decay; Solar Flares; Solar X-Rays; Bremsstrahlung; Energy Spectra; High Energy Interactions; Magnetic Flux; Monte Carlo Method; Solar Maximum Mission; Solar Physics; MAGNETOHYDRODYNAMICS: MHD; SUN: FLARES; SUN: PARTICLE EMISSION; SUN: X-RAYS; GAMMA RAYS full text sources ADS |

Effective nuclear force dependence of high energy gamma ray production

Effective nuclear force dependence of high energy gamma ray production