scholarly journals DIFFUSION IN MOMENTUM OF RELATIVISTIC ELECTRONS WITH A THERMAL SPREAD PASSING THROUGH AN UNDULATOR

2021 ◽  
pp. 102-105
Author(s):  
V.V. Ognivenko
Keyword(s):  
Magnetic Field ◽  
Diffusion Coefficient ◽  
Initial Energy ◽  
Energy Spread ◽  
Longitudinal Momentum ◽  
Relativistic Electrons ◽  
Free Electron Lasers ◽  
X Ray ◽  
Thermal Spread ◽  
Spatially Periodic

The longitudinal momentum diffusion of electrons moving in a spatially periodic magnetic field of an undulator is investigated, taking into account their initial energy spread. Expressions for the coefficient are obtained and the dependences of the diffusion coefficient are determined both on the distance traveled by the electrons in the undulator and on the value of the initial energy spread of the electrons. The possibility of decreasing the wavelength in X-ray free electron lasers is discussed.

scholarly journals Radio and X-ray connection in radio mini-halos: Implications for hadronic models

2020 ◽  
Vol 640 ◽  
pp. A37 ◽  
Author(s):  
A. Ignesti ◽  
G. Brunetti ◽  
M. Gitti ◽  
S. Giacintucci
Keyword(s):  
Magnetic Field ◽  
Large Fraction ◽  
Cosmic Ray ◽  
Physical Parameters ◽  
Model Parameters ◽  
Relativistic Electrons ◽  
X Rays ◽  
X Ray ◽  
Hadronic Model ◽  
Radio Halos

Context. A large fraction of cool-core clusters are known to host diffuse, steep-spectrum radio sources, called radio mini-halos, in their cores. Mini-halos reveal the presence of relativistic particles on scales of hundreds of kiloparsecs, beyond the scales directly influenced by the central active galactic nucleus (AGN), but the nature of the mechanism that produces such a population of radio-emitting, relativistic electrons is still debated. It is also unclear to what extent the AGN plays a role in the formation of mini-halos by providing the seeds of the relativistic population. Aims. In this work we explore the connection between thermal and non-thermal components of the intra-cluster medium in a sample of radio mini-halos and we study the implications within the framework of a hadronic model for the origin of the emitting electrons. Methods. For the first time, we studied the thermal and non-thermal connection by carrying out a point-to-point comparison of the radio and the X-ray surface brightness in a sample of radio mini-halos. We extended the method generally applied to giant radio halos by considering the effects of a grid randomly generated through a Monte Carlo chain. Then we used the radio and X-ray correlation to constrain the physical parameters of a hadronic model and we compared the model predictions with current observations. Results. Contrary to what is generally reported in the literature for giant radio halos, we find that the mini-halos in our sample have super-linear scaling between radio and X-rays, which suggests a peaked distribution of relativistic electrons and magnetic field. We explore the consequences of our findings on models of mini-halos. We use the four mini-halos in the sample that have a roundish brightness distribution to constrain model parameters in the case of a hadronic origin of the mini-halos. Specifically, we focus on a model where cosmic rays are injected by the central AGN and they generate secondaries in the intra-cluster medium, and we assume that the role of turbulent re-acceleration is negligible. This simple model allows us to constrain the AGN cosmic ray luminosity in the range ∼1044−46 erg s−1 and the central magnetic field in the range 10–40 μG. The resulting γ-ray fluxes calculated assuming these model parameters do not violate the upper limits on γ-ray diffuse emission set by the Fermi-LAT telescope. Further studies are now required to explore the consistency of these large magnetic fields with Faraday rotation studies and to study the interplay between the secondary electrons and the intra-cluster medium turbulence.

scholarly journals Statistics of Radio-X-Ray Emission and Magnetic Fields in the Intergalactic Medium

1990 ◽  
Vol 139 ◽  
pp. 414-415
Author(s):  
Hitoshi Hanami
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Intergalactic Medium ◽  
Relativistic Electrons ◽  
X Ray ◽  
Cooling Flows ◽  
Hot Plasma ◽  
Inverse Compton ◽  
The Magnetic Field

X-ray observations have demonstrated that the intergalactic medium in many clusters (cf. Coma, Perseus) contains a thin, hot plasma that may be produced by the accretion process in the gravitational potential of clusters with radiative cooling; this is usually called “cooling flows” (Fabian, Nulsen, and Canizares 1984; Sarazin 1986). On the other hand, the existence of radio halos in some clusters has been reported (Coma: Jaffe, Perola, and Valentijn 1976; A401: Roland et al. 1981). In addition, many elliptical galaxies in the center of clusters are also strong synchrotron radio sources. These radio emissions provide evidence for large amounts of relativistic electrons associated with the active phenomena in or around these galaxies and clusters. We can estimate the values or limits on the magnetic field in the cluster from the limits on the inverse Compton X-ray emission with the synchrotron radio emission (cf. Jaffe 1980). The intracluster field strength Bo is roughly 1 μG. It has been suggested that the influence of cosmic rays and magnetic fields is important for the properties and dynamics of the intercluster medium (Böhringer and Morfill 1988; Soker and Sarazin 1989). If cooling flows are real, this inward flow can impede the escape of the cosmic rays from the central galaxies in clusters and enhance the magnetic field. The confinement of the cosmic rays and the magnetic field in the center of clusters affects the gas of the intracluster medium.

DIFFUSION CHARACTERISTIC OF SEVERAL ELEMENTS IN COPPER DURING AN ELECTRIC SPARK PROCESSING UNDER A CONSTANT MAGNETIC FIELD

2009 ◽  
Vol 23 (19) ◽  
pp. 2369-2376 ◽  
Author(s):  
DINA GERTSRIKEN ◽  
VLADIMIR MAZANKO ◽  
SHENGRU QIAO ◽  
CHENGYU ZHANG
Keyword(s):  
Magnetic Field ◽  
Diffusion Coefficient ◽  
Constant Magnetic Field ◽  
Energy Gap ◽  
Pyrolytic Graphite ◽  
X Ray ◽  
Lattice Constants ◽  
The Matrix ◽  
Mechanical Mixtures ◽  
The Magnetic Field

The surface of Cu cathode was alloyed by several elements, including pure Ni , Fe , Ag and pyrolytic graphite, during electric spark processing technology (ESP). The energy, gap between the electrode and matrix, and the total fabricating time of ESP are 0.9 J, 0.5 mm, and 30 s, respectively. The ESP was performed under a constant magnetic field (CMF) of 630 kA/m. The atom distribution profiles along the depth were measured by a serial sectioning and autoradiography. The lattice constants were studied by an X-ray diffractometer. The results show that there is one or several concentration peaks in the subsurface of Cu . When the depth is beyond the location corresponding to the concentration peaks, the concentration distribution in the matrix can be described by an exponential function. Fe and C atoms can homogeneously diffuse into the Cu lattice, accompanied by mechanical mixtures, and no traces of diffusion along the grain boundaries can be found. Comparing with the condition without a CMF, the diffusion coefficient decreases when the magnetic field is parallel to the surface, whereas the diffusion coefficient is the smallest when the magnetic field is perpendicular to the surface. The lattice constant of Cu becomes smaller after the ESP.

Collective Ion Acceleration by Relativistic Electron Rings in the Magnetosphere

1982 ◽  
Vol 37 (8) ◽  
pp. 946-953
Author(s):  
U. Schumacher ◽  
R. W. Boswell
Keyword(s):  
Magnetic Field ◽  
Initial Energy ◽  
Local Magnetic Field ◽  
Relativistic Electrons ◽  
Polar Regions ◽  
Drift Motion ◽  
Field Lines ◽  
Constant Altitude ◽  
The Magnetic Field ◽  
Magnetospheric Field

Calculations are presented which show that the collective acceleration of ions by rings of relativistic electrons seems feasible in the polar regions of a dipolar magnetospheric field. The well known magnetic field of the earth is taken as an example and it is found that with rings of electrons of only 4 MeV initial energy, deuterons can be accelerated up to energies of about 50 MeV from rest in a distance of one third of an earth radius. Although the drift motion of the electron rings across the magnetic field lines is negligible for latitudes greater than 45°, in the equatorial plane the ring drifts at constant altitude with a speed proportional to the local magnetic field index

scholarly journals Observation of Stimulated Emission of Radiation by Relativistic Electrons in a Spatially Periodic Transverse Magnetic Field

1976 ◽  
Vol 36 (13) ◽  
pp. 717-720 ◽  
Author(s):  
Luis R. Elias ◽  
William M. Fairbank ◽  
John M. J. Madey ◽  
H. Alan Schwettman ◽  
Todd I. Smith
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Stimulated Emission ◽  
Relativistic Electrons ◽  
Spatially Periodic

Inverse Compton X-Rays from Giant Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 256-258
Author(s):  
D. Tsakiris ◽  
J.P. Leahy ◽  
R.G. Strom ◽  
C.R. Barber
Keyword(s):  
Magnetic Field ◽  
Minimum Energy ◽  
Radio Galaxies ◽  
Relativistic Electrons ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Image Position ◽  
Low Magnetic Field

The X-ray radiation from inverse Compton scattering of CMB photons by the relativistic electrons in ‘radio’ lobes provides a direct measure of their column density at a known energy, unlike synchrotron radiation which also depends on the unknown magnetic field. Thus by combining inverse Compton and radio data we can separately determine the particle energies and field strengths, rather than having to rely on uncertain estimates like minimum energy. The predicted flux is and strong IC signal requires high radio flux and low magnetic field, properties of giant radio galaxies. On the other hand the minimum detectable count rate, Imin, increases with the target size due to the larger background contribution. As a result the detectability of IC X-rays for ROSAT PSPC B measurements is roughly, assuming a spectral index of 0.75. After making detailed prediction of SIC for a number of objects of the 3CR sample, the best candidates were 3C 236, 3C 326, and 4C 73.08.

scholarly journals X-ray emission from hot accretion flows

2013 ◽  
Vol 9 (S304) ◽  
pp. 266-269
Author(s):  
Andrzej Niedźwiecki ◽  
Fu-Guo Xie ◽  
Agnieszka Stȩpnik
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Strong Magnetic Field ◽  
Relativistic Electrons ◽  
Refined Model ◽  
X Ray ◽  
Accretion Flows ◽  
Hydrodynamic Processes ◽  
General Relativistic ◽  
Relativistic Description

AbstractRadiatively inefficient, hot accretion flows are widely considered as a relevant accretion mode in low-luminosity AGNs. We study spectral formation in such flows using a refined model with a fully general relativistic description of both the radiative (leptonic and hadronic) and hydrodynamic processes, as well as with an exact treatment of global Comptonization. We find that the X-ray spectral index–Eddington ratio anticorrelation as well as the cut-off energy measured in the best-studied objects favor accretion flows with rather strong magnetic field and with a weak direct heating of electrons. Furthermore, they require a much stronger source of seed photons than considered in previous studies. The nonthermal synchrotron radiation of relativistic electrons seems to be the most likely process capable of providing a sufficient flux of seed photons. Hadronic processes, which should occur due to basic properties of hot flows, provide an attractive explanation for the origin of such electrons.

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