scholarly journals Gamma-ray emission from pulsar binaries

2012 ◽  
Vol 8 (S291) ◽  
pp. 418-418
Author(s):  
John Kirk ◽  
Iwona Mochol
Keyword(s):  
Magnetic Field ◽  
Binary Systems ◽  
Gamma Ray ◽  
High Energy ◽  
Low Density ◽  
Inverse Compton Scattering ◽  
Poynting Flux ◽  
Inverse Compton ◽  
Shock Precursor ◽  
The Waves

AbstractPulsar winds, containing charged particles, waves and a net (phase-averaged) magnetic field, are thought to fuel the high-energy emission from several gamma-ray binaries. They terminate where the ram pressure matches that of the surroundings - which, in binaries, is provided by the wind of the companion. Before termination, pulsed emission can be produced by inverse Compton scattering of photons from the companion by particles in the waves. After termination, both the bulk kinetic energy of the particles and the Poynting flux in the waves are dissipated into an energetic particle population embedded in the surviving phase-averaged magnetic field. Pulsed emission is no longer possible, but a substantial flux of unpulsed high-energy photons can be produced. I will present results showing that the physical conditions at the termination shock can be divided into two regimes: a high density one, where current sheets in the wind are first compressed by an MHD shock and subsequently dissipate by reconnection, and a low density one, where the wind can first convert into an electromagnetic wave in the shock precursor, which then damps and merges into the wind nebula. The shocks surrounding isolated pulsars fall into the low-density category, but those around pulsars in binary systems, may transit from one regime to the other according to binary phase. The implications of the shock-structure dichotomy for these objects will be discussed.

scholarly journals Inverse-Compton scattering in the resolved jet of the high-redshift quasar PKS J1421−0643

2020 ◽  
Vol 497 (1) ◽  
pp. 988-1000 ◽  
Author(s):  
D M Worrall ◽  
M Birkinshaw ◽  
H L Marshall ◽  
D A Schwartz ◽  
A Siemiginowska ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Lorentz Factor ◽  
High Energy ◽  
Radio Spectrum ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Jet Power

ABSTRACT Despite the fact that kpc-scale inverse-Compton (iC) scattering of cosmic microwave background (CMB) photons into the X-ray band is mandated, proof of detection in resolved quasar jets is often insecure. High redshift provides favourable conditions due to the increased energy density of the CMB, and it allows constraints to be placed on the radio synchrotron-emitting electron component at high energies that are otherwise inaccessible. We present new X-ray, optical, and radio results from Chandra, HST, and the VLA for the core and resolved jet in the z = 3.69 quasar PKS J1421−0643. The X-ray jet extends for about 4.5 arcsec (32 kpc projected length). The jet’s radio spectrum is abnormally steep and consistent with electrons being accelerated to a maximum Lorentz factor of about 5000. Results argue in favour of the detection of iC X-rays for modest magnetic field strength of a few nT, Doppler factor of about 4, and viewing angle of about 15°, and predict the jet to be largely invisible in most other spectral bands including the far- and mid-infrared and high-energy gamma-ray. The jet power is estimated to be about 3 × 1046 erg s−1 which is of order a tenth of the quasar bolometric power, for an electron–positron jet. The jet radiative power is only about 0.07 per cent of the jet power, with a smaller radiated power ratio if the jet contains heavy particles, so most of the jet power is available for heating the intergalactic medium.

scholarly journals GAMMA-RAY EMISSION OF RELATIVISTIC JETS AS A SUPERCRITICAL PROCESS

2008 ◽  
Vol 17 (09) ◽  
pp. 1611-1617 ◽  
Author(s):  
B. E. STERN ◽  
J. POUTANEN
Keyword(s):  
Gamma Ray ◽  
Galactic Nuclei ◽  
Lorentz Factor ◽  
High Energy ◽  
Relativistic Fluids ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Astrophysical Objects ◽  
Particle Propagation ◽  
The Impact

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.

PULSED HIGH-ENERGY EMISSION AND PHASE-RESOLVED SPECTRA BY INVERSE COMPTON SCATTERING IN A PULSAR STRIPED WIND

2008 ◽  
Vol 17 (10) ◽  
pp. 1969-1976
Author(s):  
JÉRÔME PÉTRI ◽  
JOHN G. KIRK
Keyword(s):  
Gamma Ray ◽  
Direct Consequence ◽  
High Energy ◽  
Light Curves ◽  
Inverse Compton Scattering ◽  
Energy Emission ◽  
Inverse Compton ◽  
Pulse Structure ◽  
And Behavior ◽  
High Energy Emission

To date, seven gamma-ray pulsars are known, showing pulsed emission up to tens of GeV and associated light-curves with a double-pulse structure. We study this pulsed high-energy emission in the framework of the striped wind model. By numerical integration of the time-dependent emissivity in the current sheets, we compute the phase-dependent spectral variability of the inverse Compton radiation. Several light curves and spectra are presented. The pulses are a direct consequence of relativistic beaming. Our model is able to explain some of the high-energy (10 MeV–10 GeV) spectral features and behavior of several gamma-ray pulsars, such as Geminga and Vela.

A MODEL FOR THE INNER JET HIGH-ENERGY EMISSION OF CENTAURUS A

2010 ◽  
Vol 19 (06) ◽  
pp. 937-942
Author(s):  
MARIANA ORELLANA ◽  
GUSTAVO E. ROMERO
Keyword(s):  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Meson Production ◽  
High Energy ◽  
Spectral Energy ◽  
Hadronic Interactions ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Great Relevance ◽  
Centaurus A

We investigate the spectral energy distribution (SED) of Centaurus A resulting from a steady compact acceleration region, located close to the central black hole, where both leptonic and hadronic relativistic populations arise. We present here results of such a model, where we have considered synchrotron radiation by primary electrons and protons, inverse Compton scattering, and gamma-ray emission originated by the inelastic hadronic interactions between relativistic protons and cold nuclei within the jets. Photo-meson production by relativistic hadrons were also taken into account, as well as the effects of secondary particles injected by all interactions. The internal and external absorption of gamma-rays is shown to be of great relevance to shape the observable SED, which was also recently constrained by the results of Fermi and HESS.

scholarly journals EMISSION FROM LARGE-SCALE JETS IN QUASARS

2008 ◽  
Vol 17 (09) ◽  
pp. 1475-1481 ◽  
Author(s):  
YASUNOBU UCHIYAMA
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
High Energy ◽  
X Rays ◽  
Microwave Background ◽  
Electron Population ◽  
Inverse Compton Scattering ◽  
Relativistic Jet ◽  
Inverse Compton ◽  
Quasar Jets

We consider the emission processes in the large-scale jets of powerful quasars based on the results obtained with the VLA, Spitzer, Hubble, and Chandra. We show that two archetypal jets, 3C 273 and PKS 1136–135, have two distinct spectral components on large-scales: (1) the low-energy (LE) synchrotron spectrum extending from radio to infrared, and (2) the high-energy (HE) component arising from optical and extending to X-rays. The X-ray emission in quasar jets is often attributed to inverse-Compton scattering of cosmic microwave background (CMB) photons by radio-emitting electrons in a highly relativistic jet. However, recent data prefer synchrotron radiation by a second distinct electron population as the origin of the HE component. We anticipate that optical polarimetry with Hubble will establish the synchrotron nature of the HE component. Gamma-ray observations with GLAST (renamed as the Fermi Gamma-ray Space Telescope), as well as future TeV observations, are expected to place important constraints on the jet models.

ON THE ORIGIN OF HIGH ENERGY GAMMA-RAYS FROM GIANT RADIO LOBES CENTARUS A

2012 ◽  
Vol 12 ◽  
pp. 224-228
Author(s):  
N. SAHAKYAN
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Radio Galaxy ◽  
High Energy ◽  
Radiation Mechanisms ◽  
Inverse Compton Scattering ◽  
High Energy Gamma ◽  
Inverse Compton ◽  
Energy Gamma ◽  
Low Density Plasma

Recently Fermi LAT collaboration reported the detection of high energy gamma-ray signal from giant lobes of the radio galaxy Centaurus A. We discuss the origin of this radiation and the possible radiation mechanisms, including inverse-Compton scattering of low energy photons and interaction of relativistic protons with the ambient low density plasma.

scholarly journals Gamma-ray source through inverse Compton scattering in a thermal hohlraum

2013 ◽  
Vol 31 (4) ◽  
pp. 607-611 ◽  
Author(s):  
Y.L. Ping ◽  
X.T. He ◽  
H. Zhang ◽  
B. Qiao ◽  
H.B. Cai ◽  
...  
Keyword(s):  
Electron Beam ◽  
Relativistic Electron ◽  
Compton Scattering ◽  
Relativistic Electron Beam ◽  
Gamma Ray ◽  
High Energy ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Energy Gamma ◽  
Background Temperature

AbstractA new inverse Compton scattering scheme for production of high-energy Gamma-ray sources is proposed in which a Giga-electronvolt (GeV) electron beam is injected into a thermal hohlraum. It is found that by increasing the hohlraum background temperature, the scattered photons experience kinematic pileup, resulting in more monochromatic spectrum and smaller scattering angle. When a relativistic electron beam with energy 1 GeV and charge 10nC is injected into a 0.5 keV hohlraum, 80% of the scattered photons have energy above 0.5 GeV.

scholarly journals Some Theoretical Studies of Two Gamma-Ray Blazars: PKS 0528+134 and Mrk 421

1998 ◽  
Vol 164 ◽  
pp. 93-94
Author(s):  
S. J. Qian ◽  
X. Z. Zhang ◽  
A. Witzel ◽  
T. P. Krichbaum ◽  
S. Britzen ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Relativistic Electrons ◽  
Quiescent State ◽  
Theoretical Studies ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
High Energy Tail ◽  
Inverse Compton ◽  
Energy Gamma

AbstractThe high energy gamma-ray flares observed in PKS 0528+134 are interpreted in terms of the external inverse Compton scattering (EICS) mechanism. The evolutional relationship between the gamma-ray flares and the associated mm-radio outbursts is investigated. The TeV/X-ray flare detected in May of 1994 from Mrk 421 is interpreted in terms of the SSC mechanism and it is shown that it may be due to the acceleration of relativistic electrons with an initially flat energy spectrum (N(E)∝E−s with s~1.5), rather than just a flattening of the high energy tail in the electron energy distribution of the source in the quiescent state.

scholarly journals Cosmic-ray acceleration and escape from post-adiabatic supernova remnants

2020 ◽  
Vol 634 ◽  
pp. A59 ◽  
Author(s):  
R. Brose ◽  
M. Pohl ◽  
I. Sushch ◽  
O. Petruk ◽  
T. Kuzyo
Keyword(s):  
Cosmic Rays ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Transport Equations ◽  
Low Density ◽  
Magnetic Turbulence ◽  
Wide Range ◽  
Inverse Compton

Context. Supernova remnants are known to accelerate cosmic rays on account of their nonthermal emission of radio waves, X-rays, and gamma rays. Although there are many models for the acceleration of cosmic rays in supernova remnants, the escape of cosmic rays from these sources has not yet been adequately studied. Aims. We aim to use our time-dependent acceleration code RATPaC to study the acceleration of cosmic rays and their escape in post-adiabatic supernova remnants and calculate the subsequent gamma-ray emission from inverse-Compton scattering and Pion decay. Methods. We performed spherically symmetric 1D simulations in which we simultaneously solved the transport equations for cosmic rays, magnetic turbulence, and the hydrodynamical flow of the thermal plasma in a volume large enough to keep all cosmic rays in the simulation. The transport equations for cosmic rays and magnetic turbulence were coupled via the cosmic-ray gradient and the spatial diffusion coefficient of the cosmic rays, while the cosmic-ray feedback onto the shock structure can be ignored. Our simulations span 100 000 years, thus covering the free-expansion, the Sedov–Taylor, and the beginning of the post-adiabatic phase of the remnant’s evolution. Results. At later stages of the evolution, cosmic rays over a wide range of energy can reside outside of the remnant, creating spectra that are softer than predicted by standard diffusive shock acceleration, and feature breaks in the 10 − 100 GeV-range. The total spectrum of cosmic rays released into the interstellar medium has a spectral index of s ≈ 2.4 above roughly 10 GeV which is close to that required by Galactic propagation models. We further find the gamma-ray luminosity to peak around an age of 4000 years for inverse-Compton-dominated high-energy emission. Remnants expanding in low-density media generally emit more inverse-Compton radiation, matching the fact that the brightest known supernova remnants – RCW86, Vela Jr., HESS J1731−347 and RX J1713.7−3946 – are all expanding in low density environments.

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