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.

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 Study of increased radiation when an x-ray tube is placed in a strong magnetic field

2007 ◽  
Vol 34 (2) ◽  
pp. 408-418 ◽  
Author(s):  
Zhifei Wen ◽  
Norbert J. Pelc ◽  
Walter R. Nelson ◽  
Rebecca Fahrig
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
X Ray

Evaluation of an elliptically polarized undulator for the future Taiwan Photon Source

2021 ◽  
Vol 16 (12) ◽  
pp. P12017
Author(s):  
H.-W. Luo ◽  
T.-Y. Chung ◽  
C.-H. Lee ◽  
C.-S. Hwang
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Synchrotron Radiation ◽  
Transverse Field ◽  
Longitudinal Direction ◽  
X Ray ◽  
Elliptically Polarized ◽  
Transverse Position ◽  
Photon Source ◽  
Field Integral

Abstract The resonant photon energy of an adjustable-phase undulator (APU) is varied with the relative motion of the magnet arrays along the longitudinal direction. There exists, however, a transverse field gradient (TFG) of order 100 T/m in an APU of small gap (∼10 mm). Whereas the TFG might affect the electron beam as it contributes to the dynamic field integral and the radiation integrals, the TFG might also degrade the performance of the synchrotron radiation due to the transverse position-dependent magnetic field. The effects of the TFG on the present Taiwan Photon Source (TPS) and future TPS-upgraded are analyzed to investigate the feasibility of an APU that operates in the soft x-ray region.

scholarly journals Hot Accretion Disks with Magnetic Field and Thermal Cyclo-Synchrotron Radiation

1994 ◽  
Vol 159 ◽  
pp. 485-485
Author(s):  
Masaaki Kusunose ◽  
Andrzej A. Zdziarski
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Spectral Index ◽  
Accretion Disks ◽  
Qualitative Properties ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Accretion Rates ◽  
Galactic Black Hole ◽  
Two Temperature

We study the structure of hot, two-temperature accretion disks around black holes, including the effects of thermal cyclo-synchrotron radiation and magnetic viscosity. This work is an extension of previous work by Björnsson & Svensson (1991a, b, 1992) and Kusunose & Mineshige (1992), which did not include those effects. Magnetic field, B, is assumed to be randomly oriented and determined by prescribing the ratio α = Pmag/Pgas or α = Pmag/(Pgas + Prad), where Pmag, Pgas, and Prad are the pressures of magnetic field, gas, and radiation, respectively. We find those effects do not change the qualitative properties of the disks, i.e., there are two critical accretion rates related to production of e± pairs, ṀcrU and ṀcrL that affect the number of local and global disk solutions, as recently found for the case with B = 0 (Björnsson & Svensson 1991a, b, 1992). However, a critical value of the α-viscosity parameter above which those critical accretion rates disappear becomes smaller than αcr = 1 found in the case of B = 0, for Pmag = α(Pgas + Prad). If Pmag = αPgas, on the other hand, αcr is still about unity. Moreover, when Comptonized cyclo-synchrotron radiation dominates Comptonized bremsstrahlung, radiation from the disk obeys a power law with the energy spectral index of ∼ 0.5, in a qualitative agreement with X-ray observations of AGNs and Galactic black hole candidates. The spectral index is weakly dependent on the mass accretion rate.

scholarly journals Fast and versatile polarization control of X-ray by segmented cross undulator at SPring-8

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Jun Miyawaki ◽  
Susumu Yamamoto ◽  
Yasuyuki Hirata ◽  
Masafumi Horio ◽  
Yoshihisa Harada ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Electron Trajectory ◽  
Relativistic Electrons ◽  
Experimental Science ◽  
X Ray ◽  
Polarization Control ◽  
The World ◽  
Light Matter Interaction ◽  
Experimental Approaches ◽  
Technical Details

AbstractAn X-ray is the well-known probe to examine structure of materials, including our own bodies. The X-ray beam, especially at the wavelength of nanometers, has also become significant to directly investigate electronic states of a sample. Such an X-ray is called a soft X-ray and polarization dependence of the light-matter interaction further unveils the microscopic properties, such as orbitals or spins of electrons. Generation of high brilliant beams of the polarized X-ray has linked to development of our experimental science, and it has been made by radiation from relativistic electrons at the synchrotron radiation facilities over the world. Recently, we constructed a new polarization-controlled X-ray source, the segmented cross undulator, at SPring-8, the largest synchrotron radiation facility in the world. The operation is based on interference of X-ray beams, which is sharply contrast to the conventional method of regulating electron trajectory by the mechanical control of magnets. The paradigm shift opened the measurement innovations and allowed us to design new experimental approaches to capture signals that have been hidden in materials. The present review describes the novel X-ray source with the principle of operation and the technical details of optimization. Examples of the frontier spectroscopies that use unique optical properties of the source are introduced, followed by the future prospects for next generation synchrotron radiation facilities.

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.

Behaviour of π± mesons and synchrotron radiation in a strong magnetic field

1997 ◽  
Vol 230 (5-6) ◽  
pp. 261-268 ◽  
Author(s):  
B.I. Lev ◽  
A.A. Semenov ◽  
C.V. Usenko
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Strong Magnetic Field

scholarly journals An X-ray surprise in a magnetic pulsator

2014 ◽  
Vol 9 (S307) ◽  
pp. 455-456
Author(s):  
Yaël Nazé
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Stellar Winds ◽  
X Ray ◽  
Object A ◽  
New Type

Abstractξ1 CMa is a rare β Cep star with a strong magnetic field. To gain new insight on this object, a dedicated campaign using XMM-Newton was performed. These data reveal a new type of variations, X-ray pulsations, posing a new challenge to our understanding of stellar winds.

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