scholarly journals Search for non-thermal X-ray emission in the colliding wind binary Cygnus OB2 #8A

2020 ◽  
Vol 636 ◽  
pp. A109 ◽  
Author(s):  
E. Mossoux ◽  
J. M. Pittard ◽  
G. Rauw ◽  
Y. Nazé
Keyword(s):  
Thermal Emission ◽  
Broad Band ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Thermal Radio Emission ◽  
Shock Region ◽  
Inverse Compton ◽  
First Time ◽  
Colliding Winds

Aims. Cyg OB2 #8A is a massive O-type binary displaying strong non-thermal radio emission. Owing to the compactness of this binary, emission of non-thermal X-ray photons via inverse Compton scattering is expected. Methods. We first revised the orbital solution for Cyg OB2 #8A using new optical spectra. We then reduced and analysed X-ray spectra obtained with XMM-Newton, Swift, INTEGRAL, and NuSTAR. Results. The analysis of the XMM-Newton and Swift data allows us to better characterise the X-ray emission from the stellar winds and colliding winds region at energies below 10 keV. We confirm the variation of the broad-band light curve of Cyg OB2 #8A along the orbit with, for the first time, the observation of the maximum emission around phase 0.8. The minimum ratio of the X-ray to bolometric flux of Cyg OB2 #8A remains well above the level expected for single O-type stars, indicating that the colliding wind region is not disrupted during the periastron passage. The analysis of the full set of publicly available INTEGRAL observations allows us to refine the upper limit on the non-thermal X-ray flux of the Cyg OB2 region between 20 and 200 keV. Two NuSTAR observations (phases 0.028 and 0.085) allow us to study the Cyg OB2 #8A spectrum up to 30 keV. These data do not provide evidence of the presence of non-thermal X-rays, but bring more stringent constraints on the flux of a putative non-thermal component. Finally, we computed, thanks to a new dedicated model, the anisotropic inverse Compton emission generated in the wind shock region. The theoretical non-thermal emission appears to be compatible with observational limits and the kinetic luminosity computed from these models is in good agreement with the unabsorbed flux observed below 10 keV.

Visualization of microvessels by angiography using inverse-Compton scattering X-rays in animal models

2014 ◽  
Vol 21 (6) ◽  
pp. 1327-1332 ◽  
Author(s):  
Toshiharu Fujii ◽  
Naoto Fukuyama ◽  
Chiharu Tanaka ◽  
Yoshimori Ikeya ◽  
Yoshiro Shinozaki ◽  
...  
Keyword(s):  
Compton Scattering ◽  
Photon Number ◽  
High Gain ◽  
Image Sensor ◽  
Clinical Settings ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Small Vessels ◽  
Inverse Compton

The fundamental performance of microangiography has been evaluated using the S-band linac-based inverse-Compton scattering X-ray (iCSX) method to determine how many photons would be required to apply iCSX to human microangiography. ICSX is characterized by its quasi-monochromatic nature and small focus size which are fundamental requirements for microangiography. However, the current iCSX source does not have sufficient flux for microangiography in clinical settings. It was determined whether S-band compact linac-based iCSX can visualize small vessels of excised animal organs, and the amount of X-ray photons required for real time microangiography in clinical settings was estimated. The iCSX coupled with a high-gain avalanche rushing amorphous photoconductor camera could visualize a resolution chart with only a single iCSX pulse of ∼3 ps duration; the resolution was estimated to be ∼500 µm. The iCSX coupled with an X-ray cooled charge-coupled device image sensor camera visualized seventh-order vascular branches (80 µm in diameter) of a rabbit ear by accumulating the images for 5 and 30 min, corresponding to irradiation of 3000 and 18000 iCSX pulses, respectively. The S-band linac-based iCSX visualized microvessels by accumulating the images. An iCSX source with a photon number of 3.6 × 103–5.4 × 104times greater than that used in this study may enable visualizing microvessels of human fingertips even in clinical settings.

scholarly journals Nested Kirkpatrick–Baez (Montel) optics for hard X-rays

2015 ◽  
Vol 48 (2) ◽  
pp. 558-564 ◽  
Author(s):  
Giacomo Resta ◽  
Boris Khaykovich ◽  
David Moncton
Keyword(s):  
Ray Tracing ◽  
Compton Scattering ◽  
Analytical Procedure ◽  
X Rays ◽  
Multilayer Mirrors ◽  
Comprehensive Description ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Proper Orientation

A comprehensive description and ray-tracing simulations are presented for symmetric nested Kirkpatrick–Baez (KB) mirrors, commonly used at synchrotrons and in commercial X-ray sources. This paper introduces an analytical procedure for determining the proper orientation between the two surfaces composing the nested KB optics. This procedure has been used to design and simulate collimating optics for a hard-X-ray inverse Compton scattering source. The resulting optical device is composed of two 12 cm-long parabolic surfaces coated with a laterally graded multilayer and is capable of collimating a 12 keV beam with a divergence of 5 mrad (FWHM) by a factor of ∼250. A description of the ray-tracing software that was developed to simulate the graded multilayer mirrors is included.

New insight into the origin of the GeV flare in the binary system PSR B1259-63/LS 2883 from the 2017 periastron passage

2020 ◽  
Vol 497 (1) ◽  
pp. 648-655
Author(s):  
M Chernyakova ◽  
D Malyshev ◽  
S Mc Keague ◽  
B van Soelen ◽  
J P Marais ◽  
...  
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Energy Release ◽  
Broad Band ◽  
Strong Shock ◽  
Optical Observations ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton ◽  
Pulsar Wind

ABSTRACT PSR B1259-63 is a gamma-ray binary system hosting a radio pulsar orbiting around an O9.5Ve star, LS 2883, with a period of ∼3.4 yr. The interaction of the pulsar wind with the LS 2883 outflow leads to unpulsed broad-band emission in the radio, X-rays, GeV, and TeV domains. While the radio, X-ray, and TeV light curves show rather similar behaviour, the GeV light curve appears very different with a huge outburst about a month after a periastron. The energy release during this outburst seems to significantly exceed the spin-down luminosity of the pulsar and both the GeV light curve and the energy release vary from one orbit to the next. In this paper, we present for the first time the results of optical observations of the system in 2017, and also reanalyse the available X-ray and GeV data. We present a new model in which the GeV data are explained as a combination of the bremsstrahlung and inverse Compton emission from the unshocked and weakly shocked electrons of the pulsar wind. The X-ray and TeV emission is produced by synchrotron and inverse Compton emission of energetic electrons accelerated on a strong shock arising due to stellar/pulsar winds collision. The brightness of the GeV flare is explained in our model as a beaming effect of the energy released in a cone oriented, during the time of the flare, in the direction of the observer.

scholarly journals K-edge Subtraction Computed Tomography with a Compact Synchrotron X-ray Source

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Stephanie Kulpe ◽  
Martin Dierolf ◽  
Benedikt Günther ◽  
Madleen Busse ◽  
Klaus Achterhold ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agent ◽  
Imaging Techniques ◽  
X Rays ◽  
Synchrotron Source ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
X Ray Computed ◽  
Compact Light Source

Abstract In clinical diagnosis, X-ray computed tomography (CT) is one of the most important imaging techniques. Yet, this method lacks the ability to differentiate similarly absorbing substances like commonly used iodine contrast agent and calcium which is typically seen in calcifications, kidney stones and bones. K-edge subtraction (KES) imaging can help distinguish these materials by subtracting two CT scans recorded at different X-ray energies. So far, this method mostly relies on monochromatic X-rays produced at large synchrotron facilities. Here, we present the first proof-of-principle experiment of a filter-based KES CT method performed at a compact synchrotron X-ray source based on inverse-Compton scattering, the Munich Compact Light Source (MuCLS). It is shown that iodine contrast agent and calcium can be clearly separated to provide CT volumes only showing one of the two materials. These results demonstrate that KES CT at a compact synchrotron source can become an important tool in pre-clinical research.

scholarly journals Starburst and post-starburst high-redshift protogalaxies

2019 ◽  
Vol 626 ◽  
pp. A85 ◽  
Author(s):  
Ellis R. Owen ◽  
Kinwah Wu ◽  
Xiangyu Jin ◽  
Pooja Surajbali ◽  
Noriko Kataoka
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
High Energy ◽  
Starburst Galaxies ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
High Energy Cosmic Rays ◽  
Radiation Fields ◽  
Inverse Compton

Quenching of star-formation has been identified in many starburst and post-starburst galaxies, indicating burst-like star-formation histories (SFH) in the primordial Universe. Galaxies undergoing violent episodes of star-formation are expected to be rich in high energy cosmic rays (CRs). We have investigated the role of these CRs in such environments, particularly how they could contribute to this burst-like SFH via quenching and feedback. These high energy particles interact with the baryon and radiation fields of their host via hadronic processes to produce secondary leptons. The secondary particles then also interact with ambient radiation fields to generate X-rays through inverse-Compton scattering. In addition, they can thermalise directly with the semi-ionised medium via Coulomb processes. Heating at a rate of ∼10−25 erg cm−3 s−1can be attained by Coulomb processes in a star-forming galaxy with one core-collapse SN event per decade, and this is sufficient to cause quenching of star-formation. At high-redshift, a substantial amount of CR secondary electron energy can be diverted into inverse-Compton X-ray emission. This yields an X-ray luminosity of above 1041 erg s−1by redshiftz = 7 which drives a further heating effect, operating over larger scales. This would be able to halt inflowing cold gas filaments, strangulating subsequent star-formation. We selected a sample of 16 starburst and post-starburst galaxies at 7 ≲ z ≲ 9 and determine the star-formation rates they could have sustained. We applied a model with CR injection, propagation and heating to calculate energy deposition rates in these 16 sources. Our calculations show that CR feedback cannot be neglected as it has the strength to suppress star-formation in these systems. We also show that their currently observed quiescence is consistent with the suffocation of cold inflows, probably by a combination of X-ray and CR heating.

The Munich Compact Light Source: initial performance measures

2016 ◽  
Vol 23 (5) ◽  
pp. 1137-1142 ◽  
Author(s):  
Elena Eggl ◽  
Martin Dierolf ◽  
Klaus Achterhold ◽  
Christoph Jud ◽  
Benedikt Günther ◽  
...  
Keyword(s):  
Light Source ◽  
Large Scale ◽  
Source Size ◽  
Relativistic Electrons ◽  
X Rays ◽  
Beam Hardening ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Compact Light Source

While large-scale synchrotron sources provide a highly brilliant monochromatic X-ray beam, these X-ray sources are expensive in terms of installation and maintenance, and require large amounts of space due to the size of storage rings for GeV electrons. On the other hand, laboratory X-ray tube sources can easily be implemented in laboratories or hospitals with comparatively little cost, but their performance features a lower brilliance and a polychromatic spectrum creates problems with beam hardening artifacts for imaging experiments. Over the last decade, compact synchrotron sources based on inverse Compton scattering have evolved as one of the most promising types of laboratory-scale X-ray sources: they provide a performance and brilliance that lie in between those of large-scale synchrotron sources and X-ray tube sources, with significantly reduced financial and spatial requirements. These sources produce X-rays through the collision of relativistic electrons with infrared laser photons. In this study, an analysis of the performance, such as X-ray flux, source size and spectra, of the first commercially sold compact light source, the Munich Compact Light Source, is presented.

scholarly journals Inverse-Compton scattering in the resolved jet of the high-redshift quasar PKS J1421−0643

2020 ◽  
Vol 497 (1) ◽  
pp. 988-1000 ◽  
Author(s):  
D M Worrall ◽  
M Birkinshaw ◽  
H L Marshall ◽  
D A Schwartz ◽  
A Siemiginowska ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Lorentz Factor ◽  
High Energy ◽  
Radio Spectrum ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Jet Power

ABSTRACT Despite the fact that kpc-scale inverse-Compton (iC) scattering of cosmic microwave background (CMB) photons into the X-ray band is mandated, proof of detection in resolved quasar jets is often insecure. High redshift provides favourable conditions due to the increased energy density of the CMB, and it allows constraints to be placed on the radio synchrotron-emitting electron component at high energies that are otherwise inaccessible. We present new X-ray, optical, and radio results from Chandra, HST, and the VLA for the core and resolved jet in the z = 3.69 quasar PKS J1421−0643. The X-ray jet extends for about 4.5 arcsec (32 kpc projected length). The jet’s radio spectrum is abnormally steep and consistent with electrons being accelerated to a maximum Lorentz factor of about 5000. Results argue in favour of the detection of iC X-rays for modest magnetic field strength of a few nT, Doppler factor of about 4, and viewing angle of about 15°, and predict the jet to be largely invisible in most other spectral bands including the far- and mid-infrared and high-energy gamma-ray. The jet power is estimated to be about 3 × 1046 erg s−1 which is of order a tenth of the quasar bolometric power, for an electron–positron jet. The jet radiative power is only about 0.07 per cent of the jet power, with a smaller radiated power ratio if the jet contains heavy particles, so most of the jet power is available for heating the intergalactic medium.

scholarly journals The first broad-band X-ray view of the narrow-line Seyfert 1 Ton S180

2020 ◽  
Vol 497 (2) ◽  
pp. 2352-2370 ◽  
Author(s):  
G A Matzeu ◽  
E Nardini ◽  
M L Parker ◽  
J N Reeves ◽  
V Braito ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Outer Part ◽  
Spectral Energy ◽  
X Rays ◽  
Narrow Line ◽  
X Ray ◽  
Extreme Uv ◽  
Reflection Grating

ABSTRACT We present joint XMM–Newton and NuSTAR observations of the ‘bare’ narrow-line Seyfert 1 Ton S180 (z = 0.062), carried out in 2016 and providing the first hard X-ray view of this luminous galaxy. We find that the 0.4–30 keV band cannot be self-consistently reproduced by relativistic reflection models, which fail to account simultaneously for the soft and hard X-ray emission. The smooth soft excess prefers extreme blurring parameters, confirmed by the nearly featureless nature of the Reflection Grating Spectrometer (RGS) spectrum, while the moderately broad Fe K line and the modest hard excess above 10 keV appear to arise in a milder gravity regime. By allowing a different origin of the soft excess, the broad-band X-ray spectrum and overall spectral energy distribution (SED) are well explained by a combination of (a) direct thermal emission from the accretion disc, dominating from the optical to the far/extreme UV; (b) Comptonization of seed disc photons by a warm (kTe ∼ 0.3 keV) and optically thick (τ ∼ 10) corona, mostly contributing to the soft X-rays; (c) Comptonization by a standard hot ($kT_{\rm \mathrm{ e}}\gtrsim 100$ keV) and optically thin (τ < 0.5) corona, responsible for the primary X-ray continuum; and (d) reflection from the mid/outer part of the disc. The two coronae are suggested to be rather compact, with $R_{\rm hot}\lesssim R_{\rm warm}\lesssim 10\, r_{\rm g}$. Our SED analysis implies that Ton S180 accretes at super-Eddington rates. This is a key condition for the launch of a wind, marginal (i.e. 3.1σ significance) evidence of which is indeed found in the RGS spectrum.

scholarly journals X-rays from the mode-switching PSR B0943+10

2017 ◽  
Vol 13 (S337) ◽  
pp. 62-65 ◽  
Author(s):  
S. Mereghetti ◽  
L. Kuiper ◽  
A. Tiengo ◽  
J. Hessels ◽  
W. Hermsen ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Thermal Emission ◽  
Mode Switching ◽  
X Rays ◽  
Radio Telescopes ◽  
Polar Cap ◽  
Radio Observations ◽  
X Ray ◽  
First Time

AbstractNew simultaneous X-ray and radio observations of the archetypal mode-switching pulsar PSR B0943+10 have been carried out with XMM-Newton and the LOFAR, LWA and Arecibo radio telescopes in November 2014. They allowed us to better constrain the X-ray spectral and variability properties of this pulsar and to detect, for the first time, the X-ray pulsations also during the X-ray-fainter mode. The combined timing and spectral analysis indicates that unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap are present during both radio modes and vary in a correlated way.

scholarly journals On the Broad Band Energy Distribution of Blazars

1994 ◽  
Vol 159 ◽  
pp. 221-232
Author(s):  
Laura Maraschi ◽  
Gabriele Ghisellini ◽  
Annalisa Celotti
Keyword(s):  
Spectral Component ◽  
Broad Band ◽  
Relativistic Electrons ◽  
Band Energy ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Γ Rays ◽  
Γ Ray ◽  
Main Components

The broad band energy distributions of blazars are revisited with particular emphasis on the sources detected in γ-rays by the Compton Observatory (GRO). The observed distributions can be broken down into two main components, corresponding to two broad peaks in the vFv representation. The first occurs in the FIR-optical range, the second in the MeV-GeV region. In the case of MKN 421, which may be representative of X-ray selected BL Lacs, the first peak is shifted to higher frequency (≃ 1016 Hz) and the γ-ray spectrum extends to TeV energies. There is general agreement that the first spectral component is due to synchrotron radiation from a relativistic jet, although some problems remain in deriving the spectrum and location of the emitting relativistic electrons. The second component, which in most objects extends from the X-ray to the γ-ray range, can be naturally interpreted as inverse Compton scattering by the same electrons producing the synchrotron photons, either on the synchrotron photons themselves (SSC) or on photons external to the jet. It is argued that multifrequency studies of these sources including γ-rays will allow to test Inverse Compton models and to distinguish between different sources of photons.

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