scholarly journals The diffuse X-ray background spectrum from 3 to 50 keV

1980 ◽  
Vol 235 ◽  
pp. 4 ◽  
Author(s):  
F. E. Marshall ◽  
E. A. Boldt ◽  
S. S. Holt ◽  
R. B. Miller ◽  
R. F. Mushotzky ◽  
...  
Keyword(s):  
Background Spectrum ◽  
X Ray ◽  
X Ray Background

The 20keV Break in the Diffuse X-ray Background Spectrum

1977 ◽  
Vol 3 (2) ◽  
pp. 131-132
Author(s):  
R. M. Hudson ◽  
R. M. Thomas ◽  
M. L. Duldig
Keyword(s):  
Spectral Index ◽  
Simple Analysis ◽  
Background Spectrum ◽  
X Ray ◽  
Independent Determination ◽  
Analysis Technique ◽  
X Ray Background

In this paper we report an independent determination of the Location of the break (change in spectral index) in the spectrum of the diffuse X-ray background by applying a simple analysis technique to data already in the literature.

scholarly journals The Soft X-ray Background Spectrum from DXS

1997 ◽  
Vol 166 ◽  
pp. 83-90 ◽  
Author(s):  
W.T. Sanders ◽  
R.J. Edgar ◽  
D.A. Liedahl ◽  
J.P. Morgenthaler
Keyword(s):  
Galactic Plane ◽  
Emission Lines ◽  
Background Spectrum ◽  
Local Bubble ◽  
X Ray ◽  
Hot Plasma ◽  
Solar Abundances ◽  
Ionic Emission ◽  
X Ray Background ◽  
Ionization Balance

AbstractThe Diffuse X-ray Spectrometer (DXS) obtained spectra of the low energy X-ray (44 – 83 Å) diffuse background near the galactic plane from galactic longitudes 150° ≲ l ≲ 300° with ≲ 3 Å spectral resolution and ~ 15° angular resolution. Thus, DXS measured X-ray spectra that arise almost entirely from within the Local Bubble. The DXS spectra show emission lines and emission-line blends, indicating that the source of the X-ray emission is thermal – hot plasma in the Local Bubble. The measured spectra are not consistent with those predicted by standard coronal models, either with solar abundances or depleted abundances, over the temperature range 105 – 107 K. The measured spectra are also inconsistent with the predictions of various non-equilibrium models. A nearly acceptable fit to DXS spectra can be achieved using a hybrid model that combines the Raymond & Smith ionization balance calculation with recently calculated (by DAL) ionic emission lines.

scholarly journals The Shape of Soft X-ray Spectra of Quasars

1989 ◽  
Vol 134 ◽  
pp. 175-176
Author(s):  
D. A. Schwartz ◽  
Y. Qian ◽  
W. H. Tucker
Keyword(s):  
Flux Density ◽  
Power Laws ◽  
Seyfert Galaxies ◽  
Background Spectrum ◽  
X Ray ◽  
The Mean ◽  
X Ray Background ◽  
Image Position ◽  
Two Parameters ◽  
Lines Of Evidence

Several lines of evidence suggest that the x-ray spectra of quasars are not simple, exact power laws: 1. when Wilkes and Elvis (1987) analyzed quasars as power laws they found an absorption less than that due to our galaxy; 2. The mean 0.3 to 3.5 keV spectral index is steeper than the mean for the 2 to 20 keV range; 3. although several lines of evidence argue that AGN provide a significant portion (perhaps all) of the x-ray background, the diffuse background spectrum does not agree with the x-ray power-law indices measured for quasars or Seyfert galaxies. Schwartz and Tucker (1988) have suggested that all the above conflicts are reconciled if the slope in the Log(flux density) vs. Log(energy) plot flattens continuously with increasing energy. In this paper we utilize one particular parameterization suggested for the flux density, which we call the “log-slope” model: where f is the flux density, K a normalization parameter which is not of interest here, and a and b are the two parameters of our fit.

scholarly journals Cosmic X-ray Background from Self-absorbed Low Luminosity AGNs

1990 ◽  
Vol 115 ◽  
pp. 276-280
Author(s):  
Jonathan E. Grindlay ◽  
Michael Luke
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Spectral Shape ◽  
Density Evolution ◽  
Background Spectrum ◽  
Asymptotic Spectrum ◽  
X Ray ◽  
Energy Cutoff ◽  
X Ray Background

AbstractA model is proposed for the origin of the diffuse cosmic x-ray background whereby it is primarily due to the contribution of low luminosity active galactic nuclei which are increasingly self-absorbed at low luminosities. Strong self-absorption for low luminosity objects allows the observed background spectrum to be flatter in the ~2-20 keV band than the asymptotic spectrum, assumed to have mean index γ ~ -0.7 up to a high energy cutoff at ~125 keV. The model can account for the spectral shape and intensity of the background spectrum, as well as its possible fluctuations, if the AGN undergo modest density evolution and the bulk of the CXB arises from AGNs at redshifts z ~ 1-3. The model can be tested with AXAF observations of low luminosity AGNs at 5-10 keV and sensitive new hard x-ray observations.

ASCA study of the X-ray background spectrum II. Absolute CXB intensity and cosmic variance

2003 ◽  
Vol 324 (12) ◽  
pp. 155-155 ◽  
Author(s):  
A. Kushino ◽  
Y. Ishisaki ◽  
U. Morita ◽  
N.Y. Yamasaki ◽  
M. Ishida ◽  
...  
Keyword(s):  
Background Spectrum ◽  
X Ray ◽  
X Ray Background

The cosmic X-ray background spectrum: an ASCA-ROSAT joint analysis

1998 ◽  
Vol 319 (1-2) ◽  
pp. 70-70
Author(s):  
T. Miyaji ◽  
G. Hasinger ◽  
M. J. Freyberg ◽  
Y. Tanaka ◽  
Y. Ishisaki ◽  
...  
Keyword(s):  
Joint Analysis ◽  
Background Spectrum ◽  
X Ray ◽  
X Ray Background

The soft X-ray background spectrum from DXS

2008 ◽  
pp. 83-90 ◽  
Author(s):  
W. T. Sanders ◽  
R. J. Edgar ◽  
D. A. Liedahl ◽  
J. P. Morgenthaler
Keyword(s):  
Background Spectrum ◽  
X Ray ◽  
X Ray Background
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