scholarly journals The High Energy X-ray Spectra of Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 29-36
Author(s):  
Steven H. Pravdo ◽  
John J. Nugent
Keyword(s):  
Lower Energy ◽  
Supernova Remnants ◽  
High Energy ◽  
X Rays ◽  
Energy Data ◽  
X Ray ◽  
Ionization Structure ◽  
Continuum Contribution ◽  
Cas A ◽  
Ionization Nonequilibrium

We present the results of fitting an ionization nonequilibrium (NIE) model to the high energy (> 5 keV) X-ray spectra of the young supernova remnants Cas A and Tycho. As an additional constraint, we demand that the models simultaneously fit lower energy, higher resolution data. For Cas A, a single NIE component can not adequately reproduce the features for the entire X-ray spectrum because 1) the ionization structure of iron ions responsible for the K emission is inconsistent with that of the ions responsible for the lower energy lines, and 2) the flux of the highest energy X-rays is underestimated. The iron K line and the high energy continuum could arise from the same NIE component but the identification of this component with either the blast wave or the ejecta in the “standard” model is difficult. In Tycho, the high energy data rule out a class of models for the lower energy data which have too large a continuum contribution.

scholarly journals Sources of X-rays from galaxies

2011 ◽  
Vol 7 (S284) ◽  
pp. 183-192
Author(s):  
Q. Daniel Wang
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Evolution ◽  
Supernova Remnants ◽  
Large Scale ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
High Energy ◽  
High Mass ◽  
X Rays ◽  
X Ray

AbstractGalactic X-ray emission is a manifestation of various high-energy phenomena and processes. The brightest X-ray sources are typically accretion-powered objects: active galactic nuclei and low- or high-mass X-ray binaries. Such objects with X-ray luminosities of ≳ 1037 ergs s−1 can now be detected individually in nearby galaxies. The contributions from fainter discrete sources (including cataclysmic variables, active binaries, young stellar objects, and supernova remnants) are well correlated with the star formation rate or stellar mass of galaxies. The study of discrete X-ray sources is essential to our understanding of stellar evolution, dynamics, and end-products as well as accretion physics. With the subtraction of the discrete source contributions, one can further map out truly diffuse X-ray emission, which can be used to trace the feedback from active galactic nuclei, as well as from stars, both young and old, in the form of stellar winds and supernovae. The X-ray emission efficiency, however, is only about 1% of the energy input rate of the stellar feedback alone. The bulk of the feedback energy is most likely gone with outflows into large-scale galactic halos. Much is yet to be investigated to comprehend the role of such outflows in regulating the ecosystem, hence the evolution of galaxies. Even the mechanism of the diffuse X-ray emission remains quite uncertain. A substantial fraction of the emission cannot arise directly from optically-thin thermal plasma, as commonly assumed, and most likely originates in its charge exchange with neutral gas. These uncertainties underscore our poor understanding of the feedback and its interplay with the galaxy evolution.

scholarly journals Search for Nonthermal X-Rays from Supernova Remnant Shells

1998 ◽  
Vol 188 ◽  
pp. 117-120
Author(s):  
R. Petre ◽  
J. Keohane ◽  
U. Hwang ◽  
G. Allen ◽  
E. Gotthelf
Keyword(s):  
Radio Emission ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Cosmic Ray ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Nonthermal Radio ◽  
Cosmic Ray Acceleration ◽  
Nonthermal Radio Emission

The suggestion that the shocks of supernova remnants (SNR's) are cosmic ray acceleration sites dates back more than 40 years. While observations of nonthermal radio emission from SNR shells indicate the ubiquity of GeV cosmic ray production, there is still theoretical debate about whether SNR shocks accelerate particles up to the well-known “knee” in the primary cosmic ray spectrum at ~3,000 TeV. Recent X-ray observations of SN1006 and other SNR's may have provided the missing observational link between SNR shocks and high energy cosmic ray acceleration. We discuss these observations and their interpretation, and summarize our ongoing efforts to find evidence from X-ray observations of cosmic ray acceleration in the shells of other SNR's.

scholarly journals Historical Supernovae and Supernova Remnants

1996 ◽  
Vol 145 ◽  
pp. 323-331 ◽  
Author(s):  
Zhenru Wang
Keyword(s):  
Tang Dynasty ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
High Energy ◽  
X Rays ◽  
Supernovae And Supernova Remnants ◽  
X Ray ◽  
The Tang Dynasty ◽  
High Energy Emission ◽  
The Relationship

The oldest historical supernova (SN), recorded by ancient Chinese in 14th Century B.C. on pieces of tortoise shells or bones, is identified with the aid of modern space γ-ray observations. Hard X-rays with energy up to 20 keV were observed from IC 443 by the X-ray satellite Ginga. We infer from these observations the age of IC 443 is ∼ 1000 — 1400 yrs. The result supports the hypothesis that IC 443 is the remnant of the historical SN 837 that occurred during the Tang Dynasty. The association between the supernova remnant (SNR) CTB 80 and SN 1408 has been hotly debated for about ten years and is briefly reviewed and discussed here. A new picture is presented to explain this association. High energy emission from historical SNRs can persist in a multiphase interstellar medium (ISM). As a result, the study of the relationship between SNRs and ancient guest stars has gained new vitality.

scholarly journals Finding fossils in Malapa breccia – medical CT scanning or micro-CT scanning?

2017 ◽  
Vol 113 (11/12) ◽  
Author(s):  
Jacqueline S. Smilg
Keyword(s):  
Computed Tomography ◽  
Lower Energy ◽  
Ct Scanning ◽  
Cost Effective ◽  
High Energy ◽  
X Rays ◽  
Micro Ct ◽  
X Ray ◽  
Mechanical Preparation ◽  
X Ray Computed

Computed tomography (CT) imaging of fossils has revolutionised the field of palaeontology, allowing researchers to gain a better understanding of fossil anatomy, preservation and conservation. Micro focus X-ray computed tomography (μXCT) has been far more extensively used for these purposes than medical CT (XCT) – mostly because of the exquisite detail that the μXCT scanning modality, using slices of micron thicknesses, can produce. High energy X-rays can potentially penetrate breccia more effectively than lower energy beams. This study demonstrates that lower energy beams produce superior images for prioritising breccia for preparation. Additionally, XCT scanners are numerous, accessible, fast and relatively cost-effective when compared to μXCT scanners – the latter are not freely available, scanning times are much longer and there are significant limitations on the size and weight of scannable objects. Breccia blocks from Malapa were scanned at high and lower energy and images were analysed for image quality, artifact and certainty of diagnosis. Results show that lower energy images are deemed superior to higher energy images for this particular application. This finding, taken together with the limitations associated with the use of μXCT for the imaging of the large breccia from Malapa, shows that XCT is the better modality for this specific application. The ability to choose fossil-bearing breccia, ahead of manual mechanical preparation by laboratory technicians, would allow for the optimal use of limited resources, manual preparatory skills as well as the curtailment of costs.

scholarly journals X-Ray Spectroscopic Measurements of Non-Equilibrium Ionization in Supernova Remnants

1984 ◽  
Vol 86 ◽  
pp. 76-79
Author(s):  
T.H. Markert ◽  
C.R. Canizares ◽  
T. Pfafman ◽  
P. Vedder ◽  
P.F. Winkler ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
X Rays ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Elemental Abundances ◽  
Ion Collisions ◽  
Ionization Structure ◽  
Cool Plasma ◽  
Collisional Ionization ◽  
Time Required

When a cool plasma is shock-heated to X-ray temperatures, the ionization structure does not attain its final, equilibrium value immmediately, but proceeds toward it through electron-ion collisions with a timescale τ ≡ net of order 1012 cm−3 sec. For supernova remnants (SNRs), where 0.1 ≤ ne ≤ 10 cm−3 typically, the time required to achieve collisional ionization equilibrium (CIE) can be greater than the age of the remnant. Even if the SNR is quite old, that part of the remnant which is emitting most of the X-rays may have been shocked relatively recently, so that the assumption of CIE may be inappropriate (see below).The question of ionization equilibrium is of great astrophysical importance in the study of SNRs because it affects the deduced values of their masses and elemental abundances (e.g. Shull 1982). Mass determinations are affected because underionized plasma generally has a much higher emissivity in soft X-rays than equilibrium plasma. Unless this is accounted for, the deduced value of the density and therefore of the mass, will be considerably overestimated.

scholarly journals Interstellar absorption of X-rays emitted by supernova remnants

1970 ◽  
Vol 37 ◽  
pp. 134-137
Author(s):  
P. Gorenstein ◽  
E. M. Kellogg ◽  
H. Gursky
Keyword(s):  
Supernova Remnants ◽  
Galactic Center ◽  
Crab Nebula ◽  
A Priori ◽  
Time Interval ◽  
Short Time Interval ◽  
X Rays ◽  
X Ray ◽  
The Galaxy ◽  
Cas A

An X-ray observation of the Cassiopeia Region by the ASE group from a sounding rocket on December 5, 1968, has resulted in the determination of locations for two sources that are precise to about 0.1 of a square degree. The positions of two well-known radio sources Cas A and SN 1572 (Tycho's Supernova), objects which are remnants of relatively recent galactic supernova, are consistent with these locations. Inasmuch as that region of the galaxy does not appear to contain nearly as large a concentration of objects as the galactic center, it is reasonable to make the identification between the X-ray sources and the supernova remnants on the basis of there being a small a priori probability of having an accidental coincidence within 0.1 square degrees. Cas A is almost certainly the same source as Cas XR-1 which the NRL group saw in an earlier survey [1]. During the December flight the Crab nebula was also observed for a short time interval.

scholarly journals Probing the Accretion Processes in Soft X-Ray Selected Polars

2015 ◽  
Vol 2 (1) ◽  
pp. 76-80
Author(s):  
I. Traulsen ◽  
K. Reinsch ◽  
A. D. Schwope
Keyword(s):  
Magnetic Field ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Flow Density ◽  
Temperature Structure ◽  
X Rays ◽  
Energy Data ◽  
X Ray ◽  
Composite Models

High-energy data of accreting white dwarfs give access to the regime of the primary accretion-induced energy release and the different proposed accretion scenarios. We perform XMM-Newton observations of polars selected due to their ROSAT hardness ratios close to -1.0 and model the emission processes in accretion column and accretion region. Our models consider the multi-temperature structure of the emission regions and are mainly determined by mass-flow density, magnetic field strength, and white-dwarf mass. To describe the full spectral energy distribution from infrared to X-rays in a physically consistent way, we include the stellar contributions and establish composite models, which will also be of relevance for future X-ray missions. We confirm the X-ray soft nature of three polars.

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

scholarly journals The interstellar medium in young supernova remnants: key to the production of cosmic X-rays and $\gamma $-rays

2021 ◽  
Vol 366 (6) ◽  
Author(s):  
Hidetoshi Sano ◽  
Yasuo Fukui
Keyword(s):  
Interstellar Medium ◽  
Supernova Remnants ◽  
Cosmic Ray ◽  
High Energy ◽  
X Rays ◽  
Interstellar Gas ◽  
High Energy Radiation ◽  
Dense Cores ◽  
The Relationship ◽  
Turbulent Velocity Field

AbstractWe review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of ∼2000 yr, focusing in particular on RX J1713.7−3946 and RCW 86. Both SNRs emit strong nonthermal X-rays and TeV $\gamma $ γ -rays, and they contain clumpy distributions of interstellar gas that includes both atomic and molecular hydrogen. We find that shock–cloud interactions provide a viable explanation for the spatial correlation between the X-rays and ISM. In these interactions, the supernova shocks hit the typically pc-scale dense cores, generating a highly turbulent velocity field that amplifies the magnetic field up to 0.1–1 mG. This amplification leads to enhanced nonthermal synchrotron emission around the clumps, whereas the cosmic-ray electrons do not penetrate the clumps. Accordingly, the nonthermal X-rays exhibit a spatial distribution similar to that of the ISM on the pc scale, while they are anticorrelated at sub-pc scales. These results predict that hadronic $\gamma $ γ -rays can be emitted from the dense cores, resulting in a spatial correspondence between the $\gamma $ γ -rays and the ISM. The current pc-scale resolution of $\gamma $ γ -ray observations is too low to resolve this correspondence. Future $\gamma $ γ -ray observations with the Cherenkov Telescope Array will be able to resolve the sub-pc-scale $\gamma $ γ -ray distribution and provide clues to the origin of these cosmic $\gamma $ γ -rays.

A multi-length-scale USAXS/SAXS facility: 10–50 keV small-angle X-ray scattering instrument

2013 ◽  
Vol 46 (5) ◽  
pp. 1508-1512 ◽  
Author(s):  
Byron Freelon ◽  
Kamlesh Suthar ◽  
Jan Ilavsky
Keyword(s):  
Small Angle ◽  
Soft Matter ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
And Performance ◽  
New Facility ◽  
Ray Scattering

Coupling small-angle X-ray scattering (SAXS) and ultra-small-angle X-ray scattering (USAXS) provides a powerful system of techniques for determining the structural organization of nanostructured materials that exhibit a wide range of characteristic length scales. A new facility that combines high-energy (HE) SAXS and USAXS has been developed at the Advanced Photon Source (APS). The application of X-rays across a range of energies, from 10 to 50 keV, offers opportunities to probe structural behavior at the nano- and microscale. An X-ray setup that can characterize both soft matter or hard matter and high-Zsamples in the solid or solution forms is described. Recent upgrades to the Sector 15ID beamline allow an extension of the X-ray energy range and improved beam intensity. The function and performance of the dedicated USAXS/HE-SAXS ChemMatCARS-APS facility is described.

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