scholarly journals High Energy Radiation Generated at Boundary Shear Layers of Relativistic Jets

2002 ◽  
Vol 19 (1) ◽  
pp. 22-25 ◽  
Author(s):  
Ł. Stawarz ◽  
M. Ostrowski
Keyword(s):  
Electron Distribution ◽  
Low Frequency ◽  
Cosmic Ray ◽  
High Energy ◽  
Particle Energy ◽  
Relativistic Electrons ◽  
Microwave Background ◽  
Boundary Shear ◽  
Inverse Compton ◽  
Energy Gains

AbstractA simple model of cosmic ray electron acceleration at the jet boundary yields a power law particle energy distribution of ultra-relativistic electrons with an energy cut-off growing with time, and, finally, a growing particle bump at the energy where energy gains equal radiation losses. For such electron distribution, in tens-of-kpc scale jets, we derived the observed time-varying spectra of synchrotron and inverse Compton radiation, including Comptonisation of synchrotron and cosmic microwave background photons. Slowly varying spectral index along the jet in the ‘low frequency’ spectral range is a natural consequence of boundary layer acceleration. Variations of the high energy bump of the electron distribution can give rise to anomalous behaviour in the X-ray band in comparison to the lower frequencies.

scholarly journals Recent Results from the CANGAROO Project

1996 ◽  
Vol 160 ◽  
pp. 363-364
Author(s):  
S.A. Dazeley ◽  
P.G. Edwards ◽  
J.R. Patterson ◽  
G.P. Rowell ◽  
M. Sinnott ◽  
...  
Keyword(s):  
Gamma Rays ◽  
South Australia ◽  
Cosmic Ray ◽  
High Energy ◽  
Relativistic Electrons ◽  
Large Numbers ◽  
Inverse Compton ◽  
Very High Energy ◽  
Large Telescopes ◽  
Very High

TheCollaboration ofAustralia andNippon for aGAmmaRayObservatory in theOutback operates two large telescopes at Woomera (South Australia), which detect the Čerenkov light images produced in the atmosphere by electronpositron cascades initiated by very high energy (~1 TeV or 1012eV) gamma rays. These gamma rays arise from a different mechanism than at EGRET energies: inverse Compton (IC) emission from relativistic electrons.The spoke-like images are recorded by a multi-pixel camera which facilitates the rejection of the large numbers of oblique and ragged cosmic ray images. A field of view ~3.5° is required. The Australian team operates a triple 4 m diameter mirror telescope, BIGRAT, with a 37 photomultiplier tube camera and energy threshold 600 GeV. The Japanese operate a single, highly accurate 3.8 m diameter f/1 telescope and high resolution 256 photomultipler tube camera. In 1998 a new 7 m telescope is planned for Woomera with a design threshold ~;200GeV.

scholarly journals Inverse Compton Scattering in pulsar physics

1996 ◽  
Vol 160 ◽  
pp. 159-162
Author(s):  
G.J. Qiao
Keyword(s):  
Radio Emission ◽  
Compton Scattering ◽  
Low Frequency ◽  
Position Angle ◽  
High Energy ◽  
Particle Energy ◽  
Important Process ◽  
Frequency Wave ◽  
Inverse Compton Scattering ◽  
Inverse Compton

AbstractInverse Compton Scattering (ICS) is a very important process not only in inner gap physics, but also for radio emission. ICS of high energy particles with thermal photons is the dominant and a very efficient mechanism of the particle energy loss above the neutron star surface, and is an important process in causing gap breakdown. The pulsar distribution in theP−Pdiagram and the observed mode changing phenomenon of some pulsars can be expained by the sparking conditions due to ICS. ICS of the secondary particles with the low frequency wave from the inner gap sparking can be responsible for radio emission. In this ICS model, many observational features of pulsar radio emission can be explained, such as: one core and two conal emission components, their different emission altitudes and relative time delay effects; spectral behavior of pulse profiles; the behavior of the linear polarization and position angle.

scholarly journals The GeV Gamma-Ray Emission Detected by Fermi-LAT Adjacent to SNR Kesteven 41

2017 ◽  
Vol 12 (S331) ◽  
pp. 310-315
Author(s):  
Bing Liu ◽  
Yang Chen ◽  
Xiao Zhang ◽  
Gao-Yuan Zhang ◽  
Yi Xing ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Observation Data ◽  
Large Area ◽  
Microwave Background ◽  
Neutral Pions ◽  
Inverse Compton ◽  
Gamma Ray Emission

AbstractGamma-ray observations for Supernova remnant (SNR)-molecular cloud (MC) association systems play an important role in the research on the acceleration and propagation of cosmic-ray protons. Through the analysis of 5.6 years of Fermi-Large Area Telescope observation data, here we report on the detection of a gamma-ray emission source near the SNR Kesteven 41 with a significance of 24σ in 0.2–300 GeV. The best-fit location of the gamma-ray source is consistent with the MC with which the SNR interacts. Several hypotheses including both leptonic and hadronic scenarios are considered to investigate the origin of these gamma-rays. The gamma-ray emission can be naturally explained by the decay of neutral pions produced via the collision between high energy protons accelerated by the shock of Kesteven 41 and the adjacent MC. The electron energy budget would be too high for the SNR if the gamma-rays were produced via inverse Compton (IC) scattering off the Cosmic Microwave Background (CMB) photons.

scholarly journals The High-energy emission of jetted AGN

2018 ◽  
Vol 14 (A30) ◽  
pp. 53-60
Author(s):  
Daniel A. Schwartz
Keyword(s):  
Black Holes ◽  
Gamma Ray ◽  
High Energy ◽  
Host Galaxy ◽  
Relativistic Electrons ◽  
Microwave Background ◽  
X Ray ◽  
Radio Jets ◽  
Inverse Compton ◽  
The Masses

AbstractQuasars with flat radio spectra and one-sided, arc-second scale, ≈ 100 mJy GHz radio jets are found to have similar scale X-ray jets in about 60% of such objects, even in short 5 to 10 ks Chandra observations. Jets emit in the GHz band via synchrotron radiation, as known from polarization measurements. The X-ray emission is explained most simply, i.e. with the fewest additional parameters, as inverse Compton (iC) scattering of cosmic microwave background (cmb) photons by the relativistic electrons in the jet. With physics based assumptions, one can estimate enthalpy fluxes upwards of 1046 erg s−1, sufficient to reverse cooling flows in clusters of galaxies, and play a significant role in the feedback process which correlates the masses of black holes and their host galaxy bulges. On a quasar-by-quasar basis, we can show that the total energy to power these jets can be supplied by the rotational energy of black holes with spin parameters as low as a = 0.3. For a few bright jets at redshifts less than 1, the Fermi gamma ray observatory shows upper limits at 10 Gev which fall below the fluxes predicted by the iC/cmb mechanism, proving the existence of multiple relativistic particle populations. At large redshifts, the cmb energy density is enhanced by a factor (1+z)4, so that iC/cmb must be the dominant mechanism for relativistic jets unless their rest frame magnetic field strength is hundreds of micro-Gauss.

scholarly journals Non-Thermal Activity and Particle Acceleration in Clusters of Galaxies

2005 ◽  
Vol 13 ◽  
pp. 317-321
Author(s):  
Vahe’ Petrosian
Keyword(s):  
Galactic Nuclei ◽  
High Energy ◽  
Relativistic Electrons ◽  
Thermal Activity ◽  
Clusters Of Galaxies ◽  
Microwave Background ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
High Energy Electrons ◽  
Inverse Compton

AbstractEvidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons, and new windows (in EUV and Hard X-ray ranges) have provided more powerful tools for its investigation. The hard X-ray observations, notably from Coma, are summarized and results of a new RXTE observations of a high red-shift cluster are presented. It is shown that the most likely emission mechanism for these radiations is the inverse Compton scattering of the cosmic microwave background photons by the same electrons responsible for the radio radiation. Various scenarios for acceleration of the electrons are considered and it is shown that the most likely model is episodic acceleration by shocks or turbulence, presumably induced by merger activity, of high energy electrons injected into the inter-cluster medium by galaxies or active galactic nuclei.

scholarly journals Very High Energy γ-Ray Generation Near The Light Cylinder of an Axisymmetric Rotator: Cos-B Like γ-Ray Sources

1992 ◽  
Vol 128 ◽  
pp. 207-208
Author(s):  
S. V. Bogovalov ◽  
YU. D. Kotov
Keyword(s):  
High Energy ◽  
Relativistic Electrons ◽  
X Rays ◽  
Inverse Compton Scattering ◽  
Light Cylinder ◽  
Radiation Spectra ◽  
Inverse Compton ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

AbstractSuper-hard γ-ray radiation spectra have been calculated. This radiation is generated near the velocity-of-light cylinder through the process of inverse-Compton scattering of relativistic electrons by thermal photons radiated by a neutron star. These calculations have been compared with observations of the Crab and Vela pulsars at 1000-GeV γ-ray energies. A correlation between γ-ray flares and those in soft (Ex ≃ lkeV) X-rays are predicted.

scholarly journals The Phenomena of High Energy Astrophysics

2003 ◽  
Vol 214 ◽  
pp. 3-20 ◽  
Author(s):  
R. D. Blandford
Keyword(s):  
Supernova Remnants ◽  
New Technology ◽  
Low Frequency ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
High Energy Astrophysics ◽  
Physical Conditions ◽  
Hot Gas ◽  
Neutrino Astronomy

A brief summary of some highlights in the study of high energy astrophysical sources over the past decade is presented. It is argued that the great progress that has been made derives largely from the application of new technology to observation throughout all of the electromagnetic and other spectra and that, on this basis, the next decade should be even more exciting. However, it is imperative to observe cosmic sources throughout these spectra in order to obtain a full understanding of their properties. In addition, it is necessary to learn the universal laws that govern the macroscopic and the microscopic behavior of cosmic plasma over a great range of physical conditions by combining observations of different classes of source. These two injunctions are illustrated by discussions of cosmology, hot gas, supernova remnants and explosions, neutron stars, black holes and ultrarelativistic outflows. New interpreations of the acceleration of Galactic cosmic rays, the cooling of hot gas in rich clusters and the nature of ultrarelativistic outflows are outlined. The new frontiers of VHE γ-ray astronomy, low frequency radio astronomy, neutrino astronomy, UHE cosmic ray physics and gravitational wave astronomy are especially promising.

scholarly journals Particle Acceleration in Extragalactic Jets and Implications for the High-Energy Emission from Blazars

1994 ◽  
Vol 159 ◽  
pp. 29-32
Author(s):  
R. Schlickeiser ◽  
C. D. Dermer
Keyword(s):  
Compton Scattering ◽  
Accretion Disk ◽  
High Energy ◽  
Relativistic Electrons ◽  
Spectral Evolution ◽  
Inverse Compton Scattering ◽  
Central Engine ◽  
Inverse Compton ◽  
Γ Rays ◽  
Γ Ray

We demonstrate that the prevalence of superluminal sources in the sample of γ-ray blazars and the peak of their luminosity spectra at γ-ray energies can be readily explained if the γ-rays result from the inverse Compton scattering of the accretion disk radiation by relativistic electrons in outflowing plasam jets. Compton scattering of external radiation by nonthermal particles in blazar jets is dominated by accretion disk photons rather than scattered radiation to distances of ∼ 0.01–0.1 pc from the central engine for standard parameters. The size of the γ-ray photosphere and the spectral evolution of the relativistic electron spectra constrain the location of the acceleration and emission sites in these objects.

scholarly journals The jet of the quasar 4C+21.35 from parsec to kiloparces scales and its role in high energy photon production

2014 ◽  
Vol 10 (S313) ◽  
pp. 33-38 ◽  
Author(s):  
Svetlana G. Jorstad ◽  
Alan P. Marscher ◽  
Daria A. Morozova ◽  
Vishal Bala ◽  
Ivan Agudo ◽  
...  
Keyword(s):  
Light Curve ◽  
Position Angle ◽  
High Energy ◽  
Relativistic Electrons ◽  
Microwave Background ◽  
Inverse Compton Scattering ◽  
The Core ◽  
Long Baseline ◽  
Γ Ray ◽  
Very Long Baseline Array

AbstractWe present an analysis of the parsec-scale jet structure of the quasar 4C+21.35 with a resolution of 0.1 milliarcseconds based on 63 epochs of Very Long Baseline Array observations at 43 GHz from 2007 June to 2014 May along with the Fermi LAT γ-ray light curve and multi-frequency optical photometric and polarimetric data. We find that the innermost jet of the quasar consists of a very compact core of size ~0.03 mas, as well as feature A1 located 0.16 ± 0.03 mas from the core. The distance of A1 remains fairly stable, but its position angle with respect to the core changes from -10 to +10 deg. We detect 4 superluminal knots in the inner jet with apparent speeds ranging from 10c to 20c. The first two components appeared in the jet during the high γ-ray state of the quasar from mid-2010 to early 2011, while the fourth knot appears to be connected with the γ-ray active state in late 2013 - early 2014. The first knot can be associated with the dramatic VHE flare in 2010 June and possesses an extreme Doppler factor ~60. We find that maxima in the γ-ray light curve coincide with epochs of interaction between the moving knots and the core and feature A1. This suggests that the core and A1 are recollimation shocks where γ-ray flares occur. The Chandra 0.5-6 keV image reveals the existence of X-ray emission in the kiloparsec scale jet of the quasar that can be explained via inverse Compton scattering off the cosmic microwave background by relativistic electrons if no deceleration occurs between the parsec- and kiloparsec-scale jets.

scholarly journals High energy cosmic photons and neutrinos

1965 ◽  
Vol 23 ◽  
pp. 195-225
Author(s):  
R. J. Gould ◽  
G. R. Burbidge
Keyword(s):  
Supernova Remnants ◽  
Crab Nebula ◽  
Meson Production ◽  
Cosmic Ray ◽  
High Energy ◽  
Relativistic Electrons ◽  
X Ray ◽  
Hard Radiation ◽  
The Galaxy ◽  
The Crab Nebula

This review concentrates primarily on the problem of interpreting the recent X-ray and γ-ray observations of celestial sources. The expected fluxes of hard radiation from various processes are estimated (when possible) and are compared with the observations. We compute the synchrotron, bremsstrahlung, and (inverse) Compton spectra originating from relativistic electrons produced (via meson production) in the galaxy and intergalactic medium by cosmic ray nuclear collisions; the spectra from π°-decay are also computed. Neutron stars, stellar coronae, and supernova remnants are reviewed as possible X-ray sources. Special consideration is given to the processes in the Crab Nebula. Extragalactic objects as discrete sources of energetic photons are considered on the basis of energy requirements; special emphasis is given to the strong radio sources and the possibility of the emission of hard radiation during their formation. The problem of the detection of cosmic neutrinos is reviewed.As yet, no definite process can be identified with any of the observed fluxes of hard radiation, although a number of relevant conclusions can be drawn on the basis of the available preliminary observational results. In particular, some cosmogonical theories can be tested.

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