Evidence that Solar X-Ray Emission is of Purely Thermal Origin (Also Observation of Far UV Flash During 28 August 1966 Proton Flare)

1972 ◽  
pp. 99-118
Author(s):  
Talbot A. Chubb
Keyword(s):  
X Ray ◽  
Thermal Origin

scholarly journals XMM-Newton and Fermi/LAT view on the supernova remnant 3C434.1

2019 ◽  
Vol 631 ◽  
pp. A179
Author(s):  
V. Doroshenko ◽  
D. Malyshev ◽  
G. Pühlhofer ◽  
B. Dincel ◽  
M. Sasaki ◽  
...  
Keyword(s):  
Power Law ◽  
Supernova Remnant ◽  
X Rays ◽  
Significant Excess ◽  
X Ray ◽  
Thermal Origin

We report on XMM-Newton observations of the supernova remnant (SNR) 3C434.1 (G94.0+1.0), the first in X-rays since the ROSAT era. Our analysis confirms the thermal origin of the observed extended X-ray emission, whose morphology appears more complex than previously reported. In particular, part of the shell shows a significantly harder spectrum which is consistent with a power law, and it is, therefore, likely of non-thermal origin. Motivated by these finding, we revisited the GeV observations of the field taken with the Fermi observatory. A significant excess associated with the remnant was detected, which is likely associated with non-thermal X-ray emission from part of the shell. The analysis of the Fermi data resulted in the serendipity discovery of GeV emission from the nearby SNR G093.7-00.2. Finally, we searched for a possible compact remnants within the shell, however, no obvious candidates could be identified due to the fairly large positional uncertainties.

scholarly journals Thermal and Non-Thermal X-Rays from SN 1006 and IC 443

1998 ◽  
Vol 188 ◽  
pp. 256-257
Author(s):  
M. Ozaki ◽  
K. Koyama
Keyword(s):  
High Temperature ◽  
Supernova Remnants ◽  
Recent Observation ◽  
X Rays ◽  
Temperature Plasma ◽  
Hard Component ◽  
X Ray ◽  
High Temperature Plasma ◽  
Thermal Origin ◽  
Non Equilibrium

From many Galactic supernova remnants (SNRs), X-ray emissions consisting of non-equilibrium ionization (NEI) plasma and additional hard component are detected. The hard emission have been usually interpreted as a high temperature plasma of = 10 keV. However, the recent observation with ASCA made it clear that the hard components of some SNRs are of non-thermal origin. Here we report the ASCA results of SN 1006 and IC 443 observations as an example of such SNRs.

scholarly journals Investigation of Laser Produced Plasma Using Space Resolved Soft X-Ray Al Spectrum and Multi-Layer Target Technique

1977 ◽  
Vol 43 ◽  
pp. 19-19
Author(s):  
H. Zmora ◽  
A. Zigler ◽  
J. L. Schwob
Keyword(s):  
Wave Front ◽  
Spatial Resolution ◽  
Line Intensity ◽  
Transport Mechanisms ◽  
Glass Laser ◽  
Power Flux ◽  
X Ray ◽  
Thermal Origin ◽  
Intensity Ratios ◽  
Classical Transport

H and He-like Al Lines and their inner-shell satellites were obtained from Al and Polyethylene layered targets irradiated by a Nd-glass laser at a power flux of 2.1013 W/cm2 . Spatial resolution was achieved using a flat crystal spectrograph incorporating a wire shadow technique. Spatial profiles of Te and ne in the expanding plasma were deduced from line intensity ratios.By varying the Al layer location in the target, the non-thermal origin of Al Kα radiation is investigated and the penetration depth of the heat wave front is determined. Comparison is made with classical transport mechanisms.

Measurements of the solar spectrum in the wavelength band 4 to 14 Å

1964 ◽  
Vol 281 (1387) ◽  
pp. 538-552 ◽  
Keyword(s):  
Thermal Emission ◽  
Solar Spectrum ◽  
X Rays ◽  
Wavelength Band ◽  
Spectral Slope ◽  
Excellent Correlation ◽  
Short Wavelength Band ◽  
Measured Intensity ◽  
X Ray ◽  
Thermal Origin

Over 150 low -resolution X -ray spectra obtained during the first 3-week period of satellite Ariel have now been reduced. These measurements illustrate the variations of the shortwavelength ‘tail* of the solar X -ray spectrum in both intensity and spectral slope, under non-flare and flare-active conditions. Typical non-flare and flare-enhanced spectra are given in the paper. It is shown that the difficulty in describing the measured intensity of non-flare X-rays in this short-wavelength band, by the emission from a thermalized coronal plasma, may be rem oved by consideration of both line and continuum radiations from one or more discrete hot regions in the corona. An electron temperature of 5 million degrees is consistent with the non-flare emission spectrum typical of 26-27 April 1962. The X -ray enhancement associated writh some chromospheric flares may also be interpreted as the thermal emission of a localized hot region, though the variability in the X-ray emission from one flare to another is quite marked. Three flares are described in detail in the paper, and of these, two appear to be of this ‘simple’, thermal type. In the third flare an unusually rapid enhancement or X -ray ‘burst’ occurs about 20 min after the flare commencement. The spectral and time development of this ‘burst’ are described and the excellent correlation with an impulsive microwave ‘burst’ and with the onset of the ionospheric effects are noted. The possibility of both microwave and X-ray bursts having a non-thermal origin is discussed.

scholarly journals ASCA and XMM-Newton observations of the galactic supernova remnant G311.5−0.3

2017 ◽  
pp. 23-31 ◽  
Author(s):  
T.G. Pannuti ◽  
M.D. Filipovic ◽  
K. Luken ◽  
G.F. Wong ◽  
P. Manojlovic ◽  
...  
Keyword(s):  
Supernova Remnant ◽  
Angular Resolution ◽  
Previous Analysis ◽  
Physical Parameters ◽  
X Ray ◽  
Spectral Fitting ◽  
Thermal Origin ◽  
First Time ◽  
Co Observations

We present an analysis of X-ray observations made with ASCA and XMM-Newton of the Galactic supernova remnant (SNR) G311.5?0.3. Prior infrared and radio observations of this SNR have revealed a shell-like morphology at both wavelengths. The spectral index of the radio emission is consistent with synchrotron emission, while the infrared colors are consistent with emission from shocked molecular hydrogen. Also previous CO observations have indicated an interaction between G311.5?0.3 and an adjacent molecular cloud. Our previous analysis of the pointed ASCA observation made of this SNR detected X-ray emission from the source for the first time but lacked the sensitivity and the angular resolution to rigorously investigate its X-ray properties. We have analyzed an archival XMM-Newton observation that included G311.5?0.3 in the field of view: this is the first time that XMM-Newton data has been used to probe the X-ray properties of this SNR. The XMM-Newton observation confirms that the X-ray emission from G311.5?0.3 is centrally concentrated and supports the classification of this source as a mixed-morphology SNR. In addition, our joint fitting of extracted ASCA and XMM-Newton spectra favor a thermal origin for the X-ray emission over a non-thermal origin. The spectral fitting parameters for our TBABS?APEC fit to the extracted spectra are NH = 4.63+1.87 ?0.85?1022 cm ?2 and kT = 0.68+0.20?0.24 keV. From these fit parameters, we derive the following values for physical parameters of the SNR: ne = 0.20 cm ?3, np = 0.17 cm ?3, MX = 21.4 M? and P/k = 3.18?106 K cm ?3.

scholarly journals Observations of Diffuse Emission from the Hot ISM

1996 ◽  
Vol 152 ◽  
pp. 269-275
Author(s):  
W.T. Sanders ◽  
R.J. Edgar
Keyword(s):  
Galactic Plane ◽  
Space Shuttle ◽  
Data Sets ◽  
Diffuse Emission ◽  
X Ray ◽  
Diffuse Background ◽  
Thermal Origin ◽  
Cosmic Abundance ◽  
Emission Models ◽  
X Ray Background

The Diffuse X-ray Spectrometer (DXS) is a Bragg-crystal spectrometer designed to obtain spectra of the diffuse x-ray background in the 83–44 Å (150–284 eV) range, with ~ 3 Å spectral resolution (10–25 eV), and ~ 15° angular resolution. It was flown successfully as an attached Shuttle payload on the STS 54 mission of NASA’s Space Shuttle Endeavour in January 1993, and spectra were obtained from the diffuse background along an arc extending roughly along the galactic plane from longitude 150° to longitude 300°. The primary conclusions so far from the analysis of the DXS data are: (1) The spectra of the diffuse background in the 83–44 Å range show emission lines or emission-line blends, indicating that the emission is thermal. Although most models of this emission have assumed that it is of thermal origin, this is the first detection of lines in the diffuse background in this wavelength range. (2) The detected spectra do not resemble the model spectra of cosmic abundance equilibrium plasmas at any temperature in the 105 – 107 K range. This is independent of the particular plasma model used, Raymond & Smith, Mewe & Kaastra, or Monsignori-Fossi & Landini. (3) The detected spectra do not resemble the model spectra of depleted abundance equilibrium plasmas at any temperature in the 105 – 107 K range, for a variety of assumed elemental depletions and the same emission models. This aspect of the analysis is not completed. (4) Tentative line identifications can be made, but other lines predicted to arise from the same ions must be of consistent strength in both the DXS and EUVE data sets.

scholarly journals On X-ray radiation of the quiet Sun

1965 ◽  
Vol 23 ◽  
pp. 81-89
Author(s):  
S. L. Mandelshtam
Keyword(s):  
Solar Spectrum ◽  
Active Regions ◽  
Experimental Measurements ◽  
X Rays ◽  
X Ray ◽  
Quiet Sun ◽  
Stable Component ◽  
Electrons And Ions ◽  
Thermal Origin ◽  
Comparison Of The Results

The conditions of production of the solar X rays are briefly discussed. The comparison of the results of recent calculations and experimental measurements supports the assumption of a thermal origin of the X ray radiation. In the “tail” of the solar spectrum below 15 Å, the main contribution comes from the free-bound radiation of electrons and ions of carbon, nitrogen, oxygen and other elements.The solar X ray radiation consist of a “quasi-stable” component, produced in undisturbed coronal regions and a “slowly varying” component generated in the active regions of the corona.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

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