Influence Of Radiation Reaction Research Articles

Classical Scattering of High-Energy Electrons off Ultra-Intense Laser Beams Taking into Account Radiation Reaction

The head-on scattering of electrons with energies from a few MeV to 5 GeV off ultrashort and ultra-intense laser pulses at petawatt intensities is investigated. Radiation reaction (RR) effects are included through the correction terms given by the Landau–Lifshitz equation. Full paraxial fields for the laser are used, including their longitudinal electric and magnetic components, and both the fundamental Gaussian TEM00 mode as well as the orbital angular momentum (OAM) mode with (l,p)=(1,0) are studied. We compare the expected behavior, as regards the influence of RR, at near-infrared (NIR) and at vacuum ultraviolet (VUV) or X-ray wavelengths.

Particle motion in ultra-strong electromagnetic fields of neutron stars: The influence of radiation reaction

Context. Neutron stars are known to be efficient accelerators that produce particles with ultra-relativistic energies. As a by-product, they also emit copious amounts of photons from radio wavelengths up to gamma rays. Aims. As a follow-up to our previous work on particle acceleration simulation near neutron stars, in this paper, we discuss the impact of radiation reaction on test particles injected into their magnetosphere. We therefore neglect the interaction between particles through the electromagnetic field as well as gravitation. Methods. We integrate numerically the reduced Landau-Lifshitz equation for electrons and protons in the vacuum field of a rotating magnetic dipole based on analytical solutions in a constant electromagnetic field. These expressions are simple in a frame where the electric and magnetic field are parallel. Lorentz transforms are used to switch back and forth between this frame and the observer frame. Results. We found that, though due solely to the Lorentz force, electrons reach Lorentz factors up to γ = 1014 and protons reach them up to γ = 1010.7. When radiation reaction is enabled, electrons reach energies up to γ = 1010.5 and protons reach energies up to γ = 108.3. The second set of values are more realistic since the radiation reaction feedback is predominant within the magnetosphere. Moreover, as expected, symmetrical behaviours between the north and south hemispheres are highlighted, either with respect to the location around the neutron star or with respect to particles of opposite charge to mass ratio (q/m). Consequently, it is useless to simulate the full set of geometrical parameters in an effort to obtain an overview of all possibilities. Conclusions. The study of the influence of the magnetic dipolar moment inclination shows similar behaviours regardless of whether radiation reaction is enabled. Protons (respectively electrons) impact the surface of the neutron star less as the inclination angle increases (decreases for electrons), while if the rotation and magnetic axes are aligned, all the protons impact the neutron star, and all the electrons impact the surface if the rotation and magnetic axes are anti-aligned. Similarly, we still find that particles are ejected away from the neutron star, in some preferred directions and Lorentz factors.

Strong Signatures of Radiation Reaction below the Radiation-Dominated Regime

The influence of radiation reaction (RR) on multiphoton Thomson scattering by an electron colliding head-on with a strong laser beam is investigated in a new regime, in which the momentum transferred on average to the electron by the laser pulse approximately compensates the one initially prepared. This equilibrium is shown to be far more sensitive to the influence of RR than previously studied scenarios. As a consequence, RR can be experimentally investigated with currently available laser systems and the underlying widely discussed theoretical equations become testable for the first time.

Computing inspirals in Kerr in the adiabatic regime: I. The scalar case

A key source for LISA will be the inspiral of compact objects into massive black holes. Recently Mino has shown that in the adiabatic limit, gravitational waveforms for these sources can be computed by using for the radiation reaction force the gradient of one half the difference between the retarded and advanced metric perturbations. Using post-Newtonian expansions, we argue that the resulting waveforms should be sufficiently accurate for signal detection with LISA. Data-analysis templates will require higher accuracy, going beyond adiabaticity; this remains a significant challenge. We describe an explicit computational procedure for obtaining waveforms based on Mino's result, for the case of a point particle coupled to a scalar field. We derive an explicit expression for the time-averaged time derivative of the Carter constant, and verify that the expression correctly predicts that circular orbits remain circular while evolving under the influence of radiation reaction. The derivation uses detailed properties of mode expansions, Green's functions and bound geodesic orbits in the Kerr spacetime, which we review in detail. This paper is about three quarters review and one quarter new material. The intent is to give a complete and self-contained treatment of scalar radiation reaction in the Kerr spacetime, in a single unified notation, starting with the Kerr metric, and ending with formulae for the time evolution of all three constants of the motion that are sufficiently explicit to be used immediately in a numerical code.

Gravitational radiation from a particle in circular orbit around a black hole. III. Stability of circular orbits under radiation reaction.

We use the Teukolsky perturbation formalism to show that (i) a particle in circular motion around a nonrotating black hole remains in a circular orbit under the influence of radiation reaction, and (ii) circular orbits are stable only if the orbital radius is greater than a critical radius ${\mathit{r}}_{\mathit{c}}$\ensuremath{\simeq}6.6792M, where M is the mass of the black hole. A circular orbit is stable if, when slightly perturbed so that it acquires a small eccentricity, the radiation reaction decreases the eccentricity; a circular orbit is unstable if the radiation reaction increases the eccentricity. Our analysis is restricted by four major assumptions: (i) the black hole is nonrotating, (ii) the eccentricity is always small, (iii) the gravitational perturbations are linear, and (iv) the adiabatic approximation (that the radiation reaction takes place over a time scale much larger than the orbital period) is valid. On the other hand, our analysis is not limited to weak-field, slow-motion situations; it is valid for particle motion in strong gravitational fields.

The influence of radiation reaction damping on the ESR lineshape of non-Lorentzian lines and magnetostatic modes

In the quasi-two-dimensional ferromagnet (C2H5NH3)2CuCl4 magnetostatic modes have been observed in the temperature rangeT=4.2...20 K by a shorted waveguide technique. The spectra differ significantly from recently reported ESR measurements in a cavity. The discrepancy can be explained by radiation damping effects which do not only broaden a line but can also essentially affect the lineshape. A simple experimental method is proposed to test the non-Lorentzian character of ESR lineshapes.

Thomson scattering of high intensity beam with radiation reaction

The influence of radiation reaction on the intensity dependent effects in the scattering of a very intense directed monochromatic beam of light is investigated. It is shown that this has negligible effect on the frequency shift. The radiation reaction imparts a slow acceleration to the electron as a result of which there is a very weak “white radiation”. It also introduces relative phase lag between the different harmonic modes of vibration of the electron.