scholarly journals Thermal and non-thermal connection in radio mini-halos

2018 ◽  
Vol 14 (S342) ◽  
pp. 137-140
Author(s):  
A. Ignesti ◽  
G. Brunetti ◽  
M. Gitti ◽  
S. Giacintucci
Keyword(s):  
Magnetic Field ◽  
Surface Brightness ◽  
X Rays ◽  
X Ray ◽  
Point Analysis ◽  
Spectrum Radio ◽  
Point To Point ◽  
The Magnetic Field ◽  
Relativistic Particles ◽  
Open Issues

AbstractSeveral cool-core clusters are known to host a radio mini-halo, a diffuse, steep-spectrum radio source located in their cores, thus probing the presence of non-thermal components as magnetic field and relativistic particles on scales not directly influenced by the central AGN. The nature of the mechanism that produces a population of radio-emitting relativistic particles on the scale of hundreds of kiloparsecs is still unclear. At the same time, it is still debated if the central AGN may play a role in the formation of mini-halos by providing the seed of the relativistic particles. We aim to investigate these open issues by studying the connection between thermal and non-thermal components of the intra-cluster medium. We performed a point-to-point analysis of the radio and the X-ray surface brightness of a compilation of mini-halos. We find that mini-halos have super-linear scalings between radio and X-rays, with radio brightness declining more steeply than the X-ray brightness. This trend is opposite to that generally observed in giant radio halos, thus marking a possible difference in the physics of the two radio sources. Finally, using the scalings between radio and X-rays and assuming a hadronic origin of mini-halos we derive constraints on the magnetic field in the core of the hosting clusters.

scholarly journals Independent estimates of energies of steep-spectrum radio sources

2013 ◽  
Vol 9 (S304) ◽  
pp. 96-99
Author(s):  
Alla Miroshnichenko
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Low Frequency ◽  
Relativistic Electrons ◽  
Frequency Spectra ◽  
Inverse Compton Scattering ◽  
Spectrum Radio ◽  
The Magnetic Field ◽  
Relativistic Particles

AbstractWe examine properties of galaxies and quasars with steep low-frequency spectra from the UTR-2 catalogue. The number of the objects have the non-thermal X-ray emission due to the inverse Compton scattering of radio photons of the microwave background by relativistic electrons. So, it is possible to estimate the magnetic field strength and the ratio of energies of the magnetic field and relativistic particles, independently. As we have received the determined values of magnetic field strength are near to one order less than those at the well-known energy equipartition condition. We conclude from the obtained energy ratio that the energy of relativistic particles prevails over the energy of magnetic field in the galaxies and quasars with steep radio spectra.

scholarly journals Magnetized black hole as an accelerator of charged particle

2021 ◽  
Author(s):  
Bobur Turimov
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Charged Particle ◽  
Active Galactic Nuclei ◽  
Zeeman Effect ◽  
Galactic Nuclei ◽  
X Ray ◽  
Fundamental Frequencies ◽  
The Magnetic Field ◽  
Relativistic Particles

Astrophysical accretion processes near the black hole candidates, such as active galactic nuclei (AGN), X-ray binary (XRB), and other astrophysical sources, are associated with high-energetic emission of radiation of relativistic particles and outflows (winds and/or jets). It is widely believed that the magnetic field plays a very important role to explain such high energetic processes in the vicinity of those astrophysical sources. In the present research note, we propose that the black hole is embedded in an asymptotically uniform magnetic field. We investigate the dynamical motion of charged particles in the vicinity of a weakly magnetized black hole. We show that in the presence of the magnetic field, the radius of the innermost stable circular orbits (ISCO) for a charged particle is located close to the black hole’s horizon. The fundamental frequencies, such as Keplerian and epicyclic frequencies of the charged particle are split into two parts due to the magnetic field, as an analog of the Zeeman effect. The orbital velocity of the charged particle measured by a local observer has been computed in the presence of the external magnetic field. We also present an analytical expression for the four-acceleration of the charged particle orbiting around black holes. Finally, we determine the intensity of the radiating charged accelerating relativistic particle orbiting around the magnetized black hole.

scholarly journals On Special Features of Non-Thermal Solar X Radiation above 10 keV

1972 ◽  
Vol 14 ◽  
pp. 761-762
Author(s):  
G. Elwert ◽  
E. Haug
Keyword(s):  
Magnetic Field ◽  
Angular Distribution ◽  
Power Law ◽  
Impulsive Phase ◽  
X Rays ◽  
Energetic Electrons ◽  
X Ray ◽  
Preferred Direction ◽  
Field Lines ◽  
The Magnetic Field

The polarization and angular distribution of solar hard X radiation above 10 keV was calculated under the assumption that the X rays originate as bremsstrahlung from energetic electrons moving in a preferred direction. The source electrons are supposed to have a power-law spectrum. These conditions are to be expected in the impulsive phase of an X-ray burst. The spiral orbits of the electrons around the magnetic field lines are taken into account.

scholarly journals Temporal and spatial variation of synchrotron X-ray stripes in Tycho’s supernova remnant

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Masamune Matsuda ◽  
Takaaki Tanaka ◽  
Hiroyuki Uchida ◽  
Yuki Amano ◽  
Takeshi Go Tsuru
Keyword(s):  
Surface Brightness ◽  
Supernova Remnant ◽  
Time Variability ◽  
X Rays ◽  
Temporal And Spatial Variation ◽  
Proton Acceleration ◽  
X Ray ◽  
Temporal And Spatial ◽  
Imaging And Spectroscopy ◽  
The Magnetic Field

Abstract The synchrotron X-ray “stripes” discovered in Tycho’s supernova remnant (SNR) have been attracting attention as they may be evidence for proton acceleration up to PeV. We analyzed Chandra data taken in 2003, 2007, 2009, and 2015 for imaging and spectroscopy of the stripes in the southwestern region of the SNR. Comparing images obtained at different epochs, we find that time variability of synchrotron X-rays is not limited to two structures previously reported but is more common in the region. Spectral analysis of nine bright stripes reveals not only their time variabilities but also a strong anti-correlation between the surface brightness and photon indices. The spectra of the nine stripes have photon indices of Γ = 2.1–2.6 and are significantly harder than those of the outer rim of the SNR in the same region with Γ = 2.7–2.9. Based on these findings, we indicate that the magnetic field is substantially amplified, and suggest that particle acceleration through a stochastic process may be at work in the stripes.

scholarly journals Magnetic field at the inner disk edge

2007 ◽  
Vol 3 (S243) ◽  
pp. 51-62 ◽  
Author(s):  
Moira Jardine ◽  
Scott G. Gregory ◽  
Jean-François Donati
Keyword(s):  
Magnetic Field ◽  
Doppler Imaging ◽  
Evolutionary Stage ◽  
X Rays ◽  
X Ray ◽  
Stellar Radius ◽  
T Tauri ◽  
The Impact ◽  
The Magnetic Field ◽  
Present Understanding

AbstractOur present understanding of the coronal structure of T Tauri stars is fragmentary and observations in different wavelength regimes often appear to give contradictory results. X-ray data suggest the presence of magnetic loops on a variety of scales, from compact loops of size less than a stellar radius, up to very large loops of up to 10 stellar radii which may connect to the disk. While some stars show a clear rotational modulation in X-rays, implying distinct bright and dark regions, many do not. This picture is complicated by the accretion process itself, which also contributes to the X-ray emission. The location of the inner edge of the accretion disk and the nature of the magnetic field there are still hotly-contested issues. Accretion indicators often suggest the presence of discrete accretion funnels. This has implications for the structure of the corona, as does the presence of an outflowing wind. All of these factors are linked to the structure of the magnetic field, which we are now beginning to unravel through Zeeman-Doppler imaging. In this review I will describe the present state of our understanding of the magnetic structure of T Tauri coronae and the impact this has during such an early evolutionary stage.

A compact permanent-magnet system for measuring magnetic circular dichroism in resonant inelastic soft X-ray scattering

2017 ◽  
Vol 24 (2) ◽  
pp. 449-455 ◽  
Author(s):  
Jun Miyawaki ◽  
Shigemasa Suga ◽  
Hidenori Fujiwara ◽  
Hideharu Niwa ◽  
Hisao Kiuchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Magnetic Circular Dichroism ◽  
X Rays ◽  
Magnet System ◽  
X Ray ◽  
X Ray Scattering ◽  
Magnetic Dichroism ◽  
The Magnetic Field ◽  
Ray Scattering

A compact and portable magnet system for measuring magnetic dichroism in resonant inelastic soft X-ray scattering (SX-RIXS) has been developed at the beamline BL07LSU in SPring-8. A magnetic circuit composed of Nd–Fe–B permanent magnets, which realised ∼0.25 T at the center of an 11 mm gap, was rotatable around the axis perpendicular to the X-ray scattering plane. Using the system, a SX-RIXS spectrum was obtained under the application of the magnetic field at an angle parallel, nearly 45° or perpendicular to the incident X-rays. A dedicated sample stage was also designed to be as compact as possible, making it possible to perform SX-RIXS measurements at arbitrary incident angles by rotating the sample stage in the gap between the magnetic poles. This system enables facile studies of magnetic dichroism in SX-RIXS for various experimental geometries of the sample and the magnetic field. A brief demonstration of the application is presented.

scholarly journals X-rays from accretion shocks in classical T Tauri stars: 2D MHD modeling and the role of local absorption

2013 ◽  
Vol 9 (S302) ◽  
pp. 48-49
Author(s):  
C. Argiroffi ◽  
R. Bonito ◽  
S. Orlando ◽  
M. Miceli ◽  
F. Reale ◽  
...  
Keyword(s):  
Magnetic Field ◽  
T Tauri Stars ◽  
X Rays ◽  
X Ray ◽  
T Tauri ◽  
Shock Region ◽  
Post Shock ◽  
The Magnetic Field ◽  
Accretion Shocks

AbstractIn classical T Tauri stars (CTTS) strong shocks are formed where the accretion funnel impacts with the denser stellar chromosphere. Although current models of accretion provide a plausible global picture of this process, some fundamental aspects are still unclear: the observed X-ray luminosity in accretion shocks is order of magnitudes lower than predicted; the observed density and temperature structures of the hot post-shock region are puzzling and still unexplained by models.To address these issues we performed 2D MHD simulations describing an accretion stream impacting onto the chromosphere of a CTTS, exploring different configurations and strengths of the magnetic field. From the model results we then synthesized the X-ray emission emerging from the hot post-shock, taking into account the local absorption due to the pre-shock stream and surrounding atmosphere.We find that the different configurations and strengths of the magnetic field profoundly affect the hot post-shock properties. Moreover the emerging X-ray emission strongly depends also on the viewing angle under which accretion is observed. Some of the explored configuration are able to reproduce the observed features of X-ray spectra of CTTS.

scholarly journals G0.173−0.42: an X-ray and radio magnetized filament near the galactic centre

2020 ◽  
Vol 500 (3) ◽  
pp. 3142-3150
Author(s):  
F Yusef-Zadeh ◽  
M Wardle ◽  
C Heinke ◽  
I Heywood ◽  
R Arendt ◽  
...  
Keyword(s):  
Galactic Centre ◽  
Physical Interaction ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Structural Details ◽  
Field Lines ◽  
The Magnetic Field ◽  
Relativistic Particles

ABSTRACT The detection of an X-ray filament associated with the radio filament G0.173–0.42 adds to four other non-thermal radio filaments with X-ray counterparts, amongst the more than 100 elongated radio structures that have been identified as synchrotron-emitting radio filaments in the inner couple of degrees of the Galactic centre. The synchrotron mechanism has also been proposed to explain the emission from X-ray filaments. However, the origin of radio filaments and the acceleration sites of energetic particles to produce synchrotron emission in radio and X-rays remain mysterious. Using MeerKAT, VLA, Chandra, WISE, and Spitzer, we present structural details of G0.173–0.42 which consists of multiple radio filaments, one of which has an X-ray counterpart. A faint oblique radio filament crosses the radio and X-ray filaments. Based on the morphology, brightening of radio and X-ray intensities, and radio spectral index variation, we argue that a physical interaction is taking place between two magnetized filaments. We consider that the reconnection of the magnetic field lines at the interaction site leads to the acceleration of particles to GeV energies. We also argue against the synchrotron mechanism for the X-ray emission due to the short ∼30 yr lifetime of TeV relativistic particles. Instead, we propose that the inverse Compton scattering mechanism is more likely to explain the X-ray emission by upscattering of seed photons emitted from a 106  L⊙ star located at the northern tip of the X-ray filament.

scholarly journals MASSIVE PHOTON PAIRS AND FEATURES OF CHANGES IN THE X-RAY BACKGROUND OF THE SOLAR CROWN AND EARTH'S MAGNETOSPHERE

2020 ◽  
Vol 2 (7(76)) ◽  
pp. 42-46
Author(s):  
I.K. Mirzoeva
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
X Rays ◽  
Earth’S Magnetosphere ◽  
X Ray ◽  
Massive Photon ◽  
Photon Pairs ◽  
Earth's Magnetosphere ◽  
X Ray Background ◽  
The Magnetic Field

The analysis of the x-ray background of the solar corona in the range of 2-25 Kev for three months of 2003 was carried out.the integrated energy spectrum was obtained according to the RHESSI project. Comparison with the data of the x-ray background of The earth's magnetosphere according to the XMM-Newton project in the soft range of x-rays allowed us to draw a conclusion about the common nature of the features of seasonal variations of the x-ray background of The earth's magnetosphere and the thermal x-ray background of the solar corona. The main reason for these changes is the splitting of massive photon pairs born from vacuum in the magnetic field of the solar corona and in the magnetic field of the Earth. According to the RHESSI, XMM-Newton, and Plank projects, theoretical and experimental evidence for the existence of massive photon pairs (ultralight scalar bosons) is provided.

scholarly journals X-Ray Emission from Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 508-508
Author(s):  
D. Q. Lamb
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Classification Scheme ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
X Rays ◽  
X Ray ◽  
Stellar Radius ◽  
The Magnetic Field

Many cataclysmic variables have been found to be hard, as well as soft, X-ray sources. Emission from the boundary layer of an optically thick accretion disk extending down to the stellar surface can, at outburst, produce soft X-rays, but the production of hard X-rays from such a disk is difficult to understand. We therefore conjecture that the sources which emit hard X-rays have magnetic fields and are, in general, rotating. We then propose a classification scheme for cataclysmic variables based on the size of the Alfven radius rA relative to the stellar radius R of the degenerate dwarf and the separation α of the binary system. We show that many of the varied characteristics displayed by the cataclysmic variable X-ray sources can be understood in terms of this ordering. We suggest that the AM Her Class (AM Her, AN UMa, W Pup, and 2A0311-23) have R ≪ α ≪ rA , the DQ Her Class (DQ Her, V533 Her, and AE Aqr) have R ≪ rA ≪ α, while the SS Cyg Class (SS Cyg, U Gem, EX Hya, and GK Per) have rA ≲ R ≪ α. Although rA depends on both the magnetic field strength of the degenerate dwarf ana the accretion rate, for comparable rates of accretion the ordering that we propose is essentially one of decreasing magnetic field strength.

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