X-ray fine structure of dense plasma in a co-axial accelerator

1972 ◽  
Vol 8 (1) ◽  
pp. 7-20 ◽  
Author(s):  
W. H. Bostick ◽  
V. Nardi ◽  
W. Prior
Keyword(s):  
Dense Plasma ◽  
Point Sources ◽  
X Rays ◽  
Axial Region ◽  
Metal Vapour ◽  
Filamentary Structure ◽  
X Ray ◽  
Hard Radiation ◽  
Cylindrical Region ◽  
Coaxial Accelerator

The intensity of X-ray sources in a focused deuterium plasma produced by a coaxial accelerator has been analysed as a function of position, X-ray energy and time of emission. The X-ray source in the axial region can be resolved (by micro- densitometer readings on X-ray pinhole camera films) as a sequence of small sources (linear dimension ∼ 0.1–0.3 mm) of hard radiation ≳ 2 ke V inside a more diffused source (cylindrical region of 1–4mm diameter) of softer X-rays. In each discharge the point sources are distributed for the most part in the general axial region of the discharge and two or more sources with different radial positions can be frequently observed for one specific value of the axial co-ordinate. Images of localized X-ray sources are also observed in the off-axis halo region. Multiple repinching of the axial plasma column or emission from metal-vapour clouds (by anode bombardment) can be ruled out in this experiment (hollow central electrode, or anode, radius 3·4 cm). The source multiplicity can be related to a complex (filamentary) structure of the plasma.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A18 ◽  
Author(s):  
C. H. A. Logan ◽  
B. J. Maughan ◽  
M. N. Bremer ◽  
P. Giles ◽  
M. Birkinshaw ◽  
...  
Keyword(s):  
Angular Resolution ◽  
False Positive Rate ◽  
High Sensitivity ◽  
Point Sources ◽  
Selection Function ◽  
X Rays ◽  
Cluster Emission ◽  
X Ray ◽  
Wide Range ◽  
Function Modelling

Context. The XMM-XXL survey has used observations from the XMM-Newton observatory to detect clusters of galaxies over a wide range in mass and redshift. The moderate PSF (FWHM ~ 6″ on-axis) of XMM-Newton means that point sources within or projected onto a cluster may not be separated from the cluster emission, leading to enhanced luminosities and affecting the selection function of the cluster survey. Aims. We present the results of short Chandra observations of 21 galaxy clusters and cluster candidates at redshifts z > 1 detected in the XMM-XXL survey in X-rays or selected in the optical and infra-red. Methods. With the superior angular resolution of Chandra, we investigate whether there are any point sources within the cluster region that were not detected by the XMM-XXL analysis pipeline, and whether any point sources were misclassified as distant clusters. Results. Of the 14 X-ray selected clusters, 9 are free from significant point source contamination, either having no previously unresolved sources detected by Chandra or with less than about 10% of the reported XXL cluster flux being resolved into point sources. Of the other five sources, one is significantly contaminated by previously unresolved AGN, and four appear to be AGN misclassified as clusters. All but one of these cases are in the subset of less secure X-ray selected cluster detections and the false positive rate is consistent with that expected from the XXL selection function modelling. We also considered a further seven optically selected cluster candidates associated with faint XXL sources that were not classed as clusters. Of these, three were shown to be AGN by Chandra, one is a cluster whose XXL survey flux was highly contaminated by unresolved AGN, while three appear to be uncontaminated clusters. By decontaminating and vetting these distant clusters, we provide a pure sample of clusters at redshift z > 1 for deeper follow-up observations, and demonstrate the utility of using Chandra snapshots to test for AGN in surveys with high sensitivity but poor angular resolution.

scholarly journals X-ray emission from Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 214-215 ◽  
Author(s):  
Gail M. Conway ◽  
You-Hua Chu
Keyword(s):  
Planetary Nebulae ◽  
Point Sources ◽  
Stellar Winds ◽  
X Rays ◽  
Will Emit ◽  
X Ray ◽  
Extended Sources ◽  
Central Stars

X-ray emission from planetary nebulae (PNe) may originate from two sources: central stars which are 100,000–200,000 K will emit soft X-rays, and shocked fast stellar winds reaching 106–107 K will emit harder X-rays. The former are point sources, while the shocked winds are expected to be extended sources emitting continuously out to the inner wall of the visible nebular shell (Weaver et al. 1977; Wrigge & Wendker 1996).

scholarly journals Broad view on hard X-ray background emission of the Galaxy

2009 ◽  
Vol 5 (H15) ◽  
pp. 810-810
Author(s):  
Roman Krivonos ◽  
Mikhail Revnivtsev ◽  
Sergey Tsygankov ◽  
Eugene Churazov ◽  
Rashid Sunyaev
Keyword(s):  
Near Infrared ◽  
Galactic Disk ◽  
Broad Band ◽  
Point Sources ◽  
X Rays ◽  
X Ray ◽  
Scientific Debate ◽  
The Galaxy ◽  
Background Emission ◽  
Galactic Background

AbstractThe nature of the Galactic Ridge X-Ray Emission (GRXE) has been under scientific debate since its discovery more than 30 years ago. It is observed as extended emission along the Galactic disk. The question was: is GRXE truly diffuse or is it composed from a large number of unresolved point sources? Using near-infrared Galaxy maps measured with the DIRBE experiment and data from the INTEGRAL observatory, we show that the galactic background in the energy range 20-60 keV originates from the stellar population of the Galaxy, which is in contrast to the diffuse nature believed before (Krivonos et al., 2007). Here we show preliminary results of studying the transition region from hard X-rays to gamma diffuse background of the Galaxy, revealing the broad band picture of Galactic Background emission.

Time resolved X-ray photography of a dense plasma focus

1977 ◽  
Vol 55 (3) ◽  
pp. 194-197 ◽  
Author(s):  
J. C. Burnett ◽  
J. Meyer ◽  
G. Rankin
Keyword(s):  
Plasma Focus ◽  
Dense Plasma ◽  
Dense Plasma Focus ◽  
X Rays ◽  
Temporal Development ◽  
Resolution Time ◽  
Time Resolved ◽  
X Ray ◽  
Hot Plasma ◽  
Schlieren Photography

The temporal development of the hot plasma in a dense plasma focus is studied by X-ray streak photography of ~2 ns resolution time. It is shown that initially a uniform X-ray emitting pinch plasma is formed which subsequently cools down until X-ray emission stops after ~50 ns. At a time of around 100 ns after initial X-ray emission coinciding with the break-up time of the pinch a second burst of X-rays is observed coming from small localized regions. The observations are compared with results obtained from time-resolved shadow and schlieren photography of a similar dense focus discharge (Peacock, Hobby, and Morgan).

scholarly journals Dispersive Spectroscopy on AXAF

1990 ◽  
Vol 115 ◽  
pp. 339-345
Author(s):  
T.H. Markert
Keyword(s):  
Focal Plane ◽  
Focal Point ◽  
Point Sources ◽  
The Other ◽  
Bragg Angle ◽  
X Rays ◽  
Crystal Spectrometer ◽  
X Ray ◽  
Transmission Grating ◽  
Imaging Detector

AbstractThere are two transmission grating spectrometers and one Bragg crystal spectrometer being developed for the Advanced X-ray Astrophysics Facility (MIT is building the crystal spectrometer and one of the grating spectrometers; the Laboratory for Space Research in Utrecht is responsible for the other grating spectrometer). The gratings divide the AXAF energy band (80 eV – 10 keV) into three regions (the MIT instrument contains gratings with two different periods) and attain resolving powers for point sources between 100 and 1800. The gratings are composed of arrays of small facets mounted on plates which can be inserted immediately behind the AXAF telescope. The dispersed spectra from the grating arrays are read out by one of the AXAF imaging instruments.The Bragg Crystal Spectrometer (BCS) is a focal plane instrument. One of eight selectable curved diffractors intercepts the AXAF X-ray beam as it diverges beyond the focal point X-rays that satisfy Bragg’s law are reflected from the crystal which, because of its curvature, re-focuses the beam onto an imaging detector. Narrow spectral regions are scanned by rocking the crystal over a range ~0.1 to 1°. Nearly the entire AXAF energy range can be studied by selecting the appropriate crystal and rotating it to the proper Bragg angle. The BCS achieves the highest spectral resolutions of the AXAF spectrometers: for 500 eV < E < 1600 eV, the FWHM of a narrow line (ΔE) is ≲ 1 eV.

scholarly journals Hot Plasma in the Galaxy

1998 ◽  
Vol 188 ◽  
pp. 47-50
Author(s):  
S. Yamauchi
Keyword(s):  
Galactic Plane ◽  
Point Sources ◽  
X Rays ◽  
Temperature Plasma ◽  
X Ray ◽  
X Ray Imaging ◽  
Hot Plasma ◽  
The Galaxy ◽  
Bulge Region ◽  
Imaging And Spectroscopy

In the X-ray band, we can see weak and extended X-rays along the Galactic plane and near the Galactic Bulge region, although these regions are dominated by many point sources (e.g., Warwick et al. 1985). The Tenma satellite discovered conspicuous emission lines from selected regions near the Galactic plane (Koyama et al. 1986). These lines are identified with K-shell line from He-like Fe, hence the extended emission is attributable to optically thin hot plasmas with temperatures of several keV. The origin of the thin hot plasmas, however, have been debatable, because no class of X-ray objects shows such high temperature plasma emissions. To investigate the origin of the extended X-rays, we are currently observing the Galactic plane regions with the ASCA satellite. In this paper, we report on the ASCA results: the hard X-ray imaging and spectroscopy of the hot plasma in the Galaxy.

scholarly journals X-Ray Observations of the Galactic Centre

1989 ◽  
Vol 136 ◽  
pp. 567-580 ◽  
Author(s):  
G. K. Skinner
Keyword(s):  
Energy Range ◽  
High Energy ◽  
Point Sources ◽  
Galactic Centre ◽  
X Rays ◽  
Diffuse Emission ◽  
Variable Source ◽  
X Ray ◽  
Centre Region ◽  
Sgr A

Observations of the galactic centre region in the photon energy range 2–500 keV are reviewed. Point sources, transients, bursts and a patch of apparently diffuse emission ~1° in extent have all been observed. The relatively detailed information obtained with the Einstein observatory just above the bottom edge of the x-ray window is starting to be supplemented by observations at higher photon energies. Although there is known to be a strong, variable, source of high energy x-rays somewhere in the region there is little reason to associate it with Sgr A West, which is detectable, but relatively weak, in the energy range below 30 keV where detailed measurements have been possible.

Optimization of neon soft X-rays emission from 200 J fast miniature dense plasma focus device: A potential source for soft X-ray lithography

2013 ◽  
Vol 377 (18) ◽  
pp. 1290-1296 ◽  
Author(s):  
S.M.P. Kalaiselvi ◽  
T.L. Tan ◽  
A. Talebitaher ◽  
P. Lee ◽  
R.S. Rawat
Keyword(s):  
Plasma Focus ◽  
Dense Plasma ◽  
Plasma Focus Device ◽  
Dense Plasma Focus ◽  
X Rays ◽  
X Ray ◽  
Potential Source

scholarly journals The Properties of Extragalactic X-Ray Sources from Visible Light Observations

1973 ◽  
Vol 55 ◽  
pp. 184-198
Author(s):  
Wallace L. W. Sargent
Keyword(s):  
Radio Galaxy ◽  
Low Frequency ◽  
Seyfert Galaxy ◽  
Point Sources ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
Detailed Structure ◽  
X Ray ◽  
Radio Halo ◽  
Ngc 4151

We describe the optical properties of the radio galaxy NGC 5128, the Seyfert galaxy NGC 4151 and the QSO 3C 273 all of which appear to be point sources of X-rays. We emphasize how the X-ray observations, particularly the low energy absorption cutoff, may help us to understand the detailed structure and source of energy in these diverse objects.The clusters of galaxies in Virgo, Perseus, Coma and Centaurus, all associated with extended X-ray sources are described. They have diverse shapes, central concentrations and galactic populations, but all contain a radio galaxy and, in several cases, a low frequency radio halo around it. It is concluded that the X-ray emission is likely to be non-thermal in origin.

scholarly journals ROSAT Observations of NGC 4258

1997 ◽  
Vol 166 ◽  
pp. 547-550
Author(s):  
Andreas Vogler ◽  
Wolfgang Pietsch
Keyword(s):  
Interstellar Medium ◽  
Point Source ◽  
Brightness Temperature ◽  
Spiral Galaxy ◽  
Surface Brightness ◽  
Point Sources ◽  
X Rays ◽  
X Ray ◽  
The Galaxy

AbstractWe performed deep follow up observations of the active spiral galaxy NGC 4258 with the ROSAT HRI and PSPC to study the different emission components. The overall luminosity of NGC 4258 is Lx ~ 2 × 1040 erg s−1 in the 0.1 – 2.4 keV ROSAT band. Besides a weak nuclear point source (Lx ≲ 1038 erg s−1) fourteen point sources are detected in the NGC 4258 disk (integral Lx ~ 3 × 1039 erg s− 1). The bulk of the X-ray emission is not resolved. The main contributions are explained by hot interstellar medium along the anomalous spiral arms of NGC 4258 (Lx ~ 1 × 1040, T ~ 0.4 keV) and by interstellar medium escaping from NGC 4258 disk into the approaching halo hemisphere (Lx ~ 4 × 1039 erg s−1, T ~ 0.2 keV)Surface brightness, temperature and absorption profiles have been taken for the X-rays in the regions of the anomalous arms. The highest and lowest absorption was received for the NW and SE tips of the arms, respectively. Our X-ray findings are compared to a model of the anomalous arms which suggests that the bar of the galaxy causes shocks in the interstellar medium and might heat a small part of it to X-ray temperatures.

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