The BeppoSAX broad-band spectrum and variability of the Seyfert 1 NGC 3783

We introduce a new model of the generation of pre-seismic electromagnetic emissions, which explains the observed phenomenology in terms of its geometry and fractal electrodynamics. Accumulated evidence indicates that an earthquake can be viewed as a critical phenomenon culminating in a large event that corresponds to a type of critical point. The principle feature of criticality is the fractal organization in both space and time. Earthquakes display a complex spatio-temporal behavior: in addition to the regularity in the rate of occurrence (e.g. Gutenberg-Richter law, Omori law), the spatial distribution of epicenters is fractal and earthquakes occur on a fractal structure of faults. Thus, the hypothesis that the fault develops as a fractal is reasonable. A mounting body of laboratory evidence suggests that micro-fracturing of rocks are associated with the appearance of spontaneous charge production and transient electromagnetic emissions (EME). The emitting, diffusing and recombination charge accompanying the micro-fracturing, can act as current generated during the crack opening. In this view, an active crack or rupture, can be simulated by a "radiating element." The idea is that a fractal geo-antenna (FGA) can be formed as an array of line elements having a fractal distribution on the ground surface as the critical point is approached. We test this idea in terms of fractal electrodynamics: we argue that the precursory VLF-VHF EM signals associated with recent earthquakes in Greece are governed by characteristics (e.g. scaling laws, temporal evolution of the spectrum content, broad band spectrum region and accelerating emission rate) predicted by fractal electrodynamics.

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Improved system for identifying biological tissue temperature using electrical impedance tomography

MATEC Web of Conferences ◽

10.1051/matecconf/201815801019 ◽

2018 ◽

Vol 158 ◽

pp. 01019 ◽

Cited By ~ 2

Author(s):

Evgeniy Korolyuk ◽

Konstantin Brazovskii

Keyword(s):

Electrical Impedance ◽

Saline Water ◽

Broad Band ◽

Experimental Studies ◽

Impedance Spectrum ◽

Target Object ◽

Tissue Temperature ◽

Band Spectrum ◽

Measuring Chamber ◽

Impedance Tomography

This paper proposes a cheap and compact medical system that determines the temperature of an object using broadband impedance tomography. This system can be used in medicine to visualize ice structure in tissue during cryosurgical operations, as well as for fault diagnosis and location in studied industrial objects. These effects are achieved by measuring electrical impedance between electrode pairs in the measuring chamber. The assembled prototype is compact, consumes little power, and allows to non-invasively determine the impedance of a target object in real time. The research included experimental studies to determine the dependence of the impedance spectrum of saline water and muscle tissue on temperature in broad band spectrum, which allowed to obtain the dependence of total electrical impedance of target objects on temperature.

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A Model of the Broad-Band Continuum of NGC 5548

Symposium - International Astronomical Union ◽

10.1017/s0074180900115876 ◽

1998 ◽

Vol 188 ◽

pp. 430-431

Author(s):

P. Magdziarz ◽

O. Blaes

Keyword(s):

Broad Band ◽

Continuum Emission ◽

Band Spectrum ◽

Complex Phase ◽

Disk Structure ◽

Three Phase ◽

Central Disk ◽

Ngc 5548 ◽

Excess Component ◽

The Continuum

We discuss a model of the central source in Seyfert 1 galaxy NGC 5548. The model assumes a three phase disk structure consisting of a cold outer disk, a hot central disk constituting a Comptonizing X/γ source, and an intermediate unstable and complex phase emitting a soft excess component. The model qualitatively explains broad-band spectrum and variability behavior assuming that the soft excess contributes significantly to the continuum emission and drives variability by geometrical changes of the intermediate disk zone.

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The broad-band spectrum of the narrow-line Seyfert 1 NGC 4748: from UV to hard X-ray

Astrophysics and Space Science ◽

10.1007/s10509-018-3447-2 ◽

2018 ◽

Vol 363 (11) ◽

Cited By ~ 2

Author(s):

A. A. Vasylenko

Keyword(s):

Broad Band ◽

Band Spectrum ◽

Narrow Line ◽

X Ray

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NuSTAR view of Be/X-ray binary pulsar 2S 1417−624 during 2018 giant outburst

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2795 ◽

2019 ◽

Vol 490 (2) ◽

pp. 2458-2466 ◽

Cited By ~ 1

Author(s):

Shivangi Gupta ◽

Sachindra Naik ◽

Gaurava K Jaisawal

Keyword(s):

Broad Band ◽

Gaussian Function ◽

Physical Models ◽

Spectral Studies ◽

Band Spectrum ◽

X Ray ◽

Binary Pulsar ◽

Double Peak Structure ◽

Peak Structure ◽

Cyclotron Line

ABSTRACT We report the results obtained from a detailed timing and spectral studies of Be/X-ray binary pulsar 2S 1417−624 using data from Swift and NuSTAR observatories. The observations were carried out at the peak of a giant outburst of the pulsar in 2018. X-ray pulsations at ∼17.475 s were detected in the source light curves up to 79 keV. The evolution of the pulse profiles with energy was found to be complex. A four-peaked profile at lower energies gradually evolved into a double-peak structure at higher energies. The pulsed fraction of the pulsar, calculated from the NuSTAR observation was found to follow an anticorrelation trend with luminosity as observed during previous giant X-ray outburst studies in 2009. The broad-band spectrum of the pulsar is well described by a composite model consisting of a cut-off power-law model modified with the interstellar absorption, a thermal blackbody component with a temperature of ≈1 keV, and a Gaussian function for the 6.4 keV iron emission line. Though the pulsar was observed at the peak of the giant outburst, there was no signature of presence of any cyclotron line feature in the spectrum. The radius of the blackbody emitting region was estimated to be ≈2 km, suggesting that the most probable site of its origin is the stellar surface of the neutron star. Physical models were also explored to understand the emission geometry of the pulsar and are discussed in the paper.

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The December 2015 re-brightening of V404 Cygni

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731768 ◽

2018 ◽

Vol 616 ◽

pp. A129 ◽

Cited By ~ 2

Author(s):

J. J. E. Kajava ◽

S. E. Motta ◽

C. Sánchez-Fernández ◽

E. Kuulkers

Keyword(s):

Broad Band ◽

High Energy ◽

Accretion Disc ◽

Band Spectrum ◽

Hard Photon ◽

Time Resolved ◽

X Ray ◽

Spectral Behaviour ◽

Black Hole Binary ◽

Spectral Cut

In December 2015 the black hole binary V404 Cyg underwent a secondary outburst after the main June 2015 event. We monitored this re-brightening with the INTEGRAL and Swift satellites, and in this paper we report the results of the time-resolved spectral analysis of these data. The December outburst shared several characteristics with the June event. The well-sampled INTEGRAL light curve shows up to ten Crab flares, which are separated by relatively weak non-flaring emission phases when compared to the June outburst. The spectra are nicely described by absorbed Comptonization models, with hard photon indices, Γ ≲ 2, and significant detections of a high-energy cut-off only during the bright flares. This is in contrast to the June outburst, where the Comptonization models gave electron temperatures mostly in the 30–50 keV range, while some spectra were soft (Γ ~ 2.5) without signs of any spectral cut-off. Similarly to the June outburst, we see clear signs of a variable local absorber in the soft energy band covered by Swift/XRT and INTEGRAL/JEM-X, which causes rapid spectral variations observed during the flares. During one flare, both Swift and INTEGRAL captured V404 Cyg in a state where the absorber was nearly Compton thick, N H ≈ 1024 cm−2, and the broad-band spectrum was similar to obscured AGN spectra, as seen during the X-ray plateaus in the June outburst. We conclude that the spectral behaviour of V404 Cyg during the December outburst was analogous with the first few days of the June outburst, both having hard X-ray flares that were intermittently influenced by obscuration due to nearly Compton-thick outflows launched from the accretion disc.

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Observation of nonlinear Landau damping of a broad-band spectrum of electron plasma waves

The Physics of Fluids ◽

10.1063/1.862047 ◽

1977 ◽

Vol 20 (9) ◽

pp. 1488 ◽

Cited By ~ 4

Author(s):

F. Gervais ◽

J. Olivain ◽

A. Quemeneur ◽

G. Matthieussent

Keyword(s):

Broad Band ◽

Plasma Waves ◽

Electron Plasma ◽

Landau Damping ◽

Band Spectrum ◽

Nonlinear Landau Damping

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Nonlinear Landau damping of a broad-band spectrum of electron plasma waves in a bounded plasma

Journal of Plasma Physics ◽

10.1017/s0022377800019887 ◽

1976 ◽

Vol 15 (3) ◽

pp. 371-380 ◽

Cited By ~ 3

Author(s):

G. Matthieussent

Keyword(s):

Boundary Value Problem ◽

Plasma Column ◽

Broad Band ◽

Plasma Waves ◽

Electron Plasma ◽

Landau Damping ◽

Band Spectrum ◽

Bounded Plasma ◽

Nonlinear Landau Damping ◽

Geometrical Effects

The nonlinear Landau damping of a broad-band spectrum of electron plasma waves propagating in a plasma column is considered.Finite geometrical effects inherent to the boundary value problem are taken into account. It is shown that nonlinear Landau damping of such a spectrum can be easily observed on a plasma column with a density of the order of 2 × 108 particles cm−3 and an electron temperature of about 3eV.

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Broad-band spectral analysis of LMXB XTE J1710−281 with Suzaku

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1516 ◽

2020 ◽

Vol 496 (1) ◽

pp. 197-205

Author(s):

Prince Sharma ◽

Rahul Sharma ◽

Chetana Jain ◽

Anjan Dutta

Keyword(s):

Spectral Analysis ◽

Broad Band ◽

Emission Spectra ◽

Band Spectrum ◽

Surface Boundary ◽

Hot Electron ◽

Spectral Parameters ◽

Surface Boundary Layer ◽

X Ray ◽

Single Temperature

ABSTRACT This work presents the broad-band time-averaged spectral analysis of neutron star (NS) low-mass X-ray binary, XTE J1710−281 by using the Suzaku archival data. The source was in a hard or an intermediate spectral state during this observation. This is the first time that a detailed spectral analysis of the persistent emission spectra of XTE J1710−281 has been done up to 30 keV with improved constraints on its spectral parameters. By simultaneously fitting the X-ray Imaging Spectrometer (0.6–9.0 keV) and the HXD-PIN (15.0–30.0 keV) data, we have modelled the persistent spectrum of the source with models comprising a soft component from accretion disc and/or NS surface/boundary layer and a hard Comptonizing component. The 0.6–30 keV continuum with neutral absorber can be described by a multicolour disc blackbody with an inner disc temperature of kTdisc = 0.28 keV, which is significantly Comptonized by the hot electron cloud with electron temperature of kTe ≈ 5 keV and described by photon index Γ = 1.86. A more complex three-component model comprising a multicolour disc blackbody ≈0.30 keV, single-temperature blackbody ≈0.65 keV, and Comptonization from the disc, partially absorbed (about 38 per cent) by an ionized absorber (log(ξ) ≈ 4) describes the broad-band spectrum equally well.

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