scholarly journals Absorption and Production of Soft X-Rays in the Galaxy

1973 ◽  
Vol 55 ◽  
pp. 235-249
Author(s):  
S. Hayakawa
Keyword(s):  
Emission Lines ◽  
Interstellar Matter ◽  
X Rays ◽  
Diffuse Component ◽  
Number Density ◽  
High Number Density ◽  
Hard Component ◽  
X Ray ◽  
Cygnus Loop ◽  
The Galaxy

The column densities of interstellar hydrogen to X-ray sources derived from their spectra are compared with those obtained from 21 cm radio observations. Referring to several observed results on Cyg X-2, Cygnus Loop etc., the interpretation of the low energy cut-off of the spectrum in terms of the interstellar absorption is subject to ambiguities due to a modification of the emission spectrum by Compton scattering in the sources and the contribution of emission lines.The result of soft X-ray sky surveys indicates that the diffuse component of soft X-rays consists of the extragalactic and the galactic components. The former has a hard component with a power law spectrum and a soft component which may be represented by an exponential spectrum. The galactic component is so soft that its spectrum may also be explained by thermal bremsstrahlung of temperature of about 0.1 keV. Its generation rate may account for the heating and ionization of interstellar matter. It is suggested that galactic diffuse soft X-rays are produced by active stars of a rather high number density.

Some recent observations of supernova remnants emitting X-rays

1979 ◽  
Vol 366 (1726) ◽  
pp. 311-327
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
X Rays ◽  
Coronal Line ◽  
Crystal Spectrometer ◽  
X Ray ◽  
Cygnus Loop ◽  
The Galaxy ◽  
Two Distinct Temperatures ◽  
Line Observation

There are currently believed to be 13 X-ray sources which can be fairly confidently identified with galactic supernova remnants. All of these sources are thought to be at reasonably small distances, thus supporting the view that absorption in the interstellar medium prevents us from seeing the more distant galactic remnants with the level of sensitivity currently available from soft X-ray instrumentation. Of the older remnants, the Cygnus Loop and Puppis-A are discussed in the light of recent observations. Several mapping experiments show that the Cygnus Loop exhibits a shell-like structure in X-rays, though with considerable fine structure. From these experiments, it is still not clear how uniform is the temperature over the X-ray emitting region. In addition, results from a crystal spectrometer are described which imply that the temperature may be higher than had been previously determined from proportional counter observations. Results from observations of Puppis-A are presented. These imply that two distinct temperatures exist in this source. It is argued that this may represent the interaction of the expanding shock front with a relatively dense interstellar cloud. The sources W44 and γ -Cygni supernova remnant are discussed and it is suggested that these may now be regarded as members of the class of confirmed X-ray emitting supernova remnants. Finally, an optical coronal line observation of the remnant N49 in the L. M. C. is considered, and it is suggested that this source is a likely candidate to be detected as the first X-ray emitting supernova remnant outside the galaxy.

scholarly journals Soft X-rays from the Galaxy

1970 ◽  
Vol 37 ◽  
pp. 406-407
Author(s):  
M. J. Rees
Keyword(s):  
Galactic Plane ◽  
Galactic Latitude ◽  
X Rays ◽  
Indirect Methods ◽  
X Ray ◽  
Background Data ◽  
Diffuse Background ◽  
The Galaxy ◽  
X Ray Background ◽  
Significant Flux

Below 1 keV, analyses of X-ray background data are complicated by galactic absorption effects, which cause the received intensity to vary with galactic latitude. Bowyer et al. (1968) observed that the diffuse background did not fall off as rapidly as was expected towards the galactic plane. One plausible interpretation of their data would be to suppose that a significant flux of soft X-rays emanates from the disc itself. I wish to discuss what could be inferred about the latter component from improved observations of its latitude-dependence, and by indirect methods.

The Characteristic X-Rays from Boron and Beryllium

1965 ◽  
Vol 9 ◽  
pp. 456-470 ◽  
Author(s):  
R. C. Ehlert ◽  
R. A. Mattson
Keyword(s):  
Proportional Counter ◽  
Soap Film ◽  
Peak Height ◽  
Half Width ◽  
Emission Lines ◽  
X Rays ◽  
Pure Element ◽  
X Ray ◽  
Number Of Layers ◽  
Lead Stearate

AbstractLead stearate and lead lignocerate multilayer soap-film structures are used to disperse the K emission lines of boron and beryllium respectively. Data are presented showing the dependence of the peak height and half-width on the number of layers in the lignocerate structure. Spectra are presented and compared for the pure element and several compounds of each element. Both electron and X-ray excitation are used. Detection is by a thin-window flow-proportional counter.

scholarly journals Projection effects in galaxy cluster samples: insights from X-ray redshifts

2019 ◽  
Vol 626 ◽  
pp. A48 ◽  
Author(s):  
M. E. Ramos-Ceja ◽  
F. Pacaud ◽  
T. H. Reiprich ◽  
K. Migkas ◽  
L. Lovisari ◽  
...  
Keyword(s):  
Spatial Information ◽  
Galaxy Cluster ◽  
X Rays ◽  
X Ray ◽  
Cluster Sample ◽  
Global Cluster ◽  
Sky Survey ◽  
The Galaxy ◽  
Flux Measurements ◽  
Cluster Properties

Presently, the largest sample of galaxy clusters selected in X-rays comes from the ROSAT All-Sky Survey (RASS). Although there have been many interesting clusters discovered with the RASS data, the broad point spread function of the ROSAT satellite limits the attainable amount of spatial information for the detected objects. This leads to the discovery of new cluster features when a re-observation is performed with higher-resolution X-ray satellites. Here we present the results from XMM-Newton observations of three clusters: RXC J2306.6−1319, ZwCl 1665, and RXC J0034.6−0208, for which the observations reveal a double or triple system of extended components. These clusters belong to the extremely expanded HIghest X-ray FLUx Galaxy Cluster Sample (eeHIFLUGCS), which is a flux-limited cluster sample (fX, 500 ≥ 5 × 10−12 erg s−1 cm−2 in the 0.1−2.4 keV energy band). For each structure in each cluster, we determine the redshift with the X-ray spectrum and find that the components are not part of the same cluster. This is confirmed by an optical spectroscopic analysis of the galaxy members. Therefore, the total number of clusters is actually seven, rather than three. We derive global cluster properties of each extended component. We compare the measured properties to lower-redshift group samples, and find a good agreement. Our flux measurements reveal that only one component of the ZwCl 1665 cluster has a flux above the eeHIFLUGCS limit, while the other clusters will no longer be part of the sample. These examples demonstrate that cluster–cluster projections can bias X-ray cluster catalogues and that with high-resolution X-ray follow-up this bias can be corrected.

scholarly journals The Galaxy Merger Origin of Hot Gaseous Halos of Ellipticals

2004 ◽  
Vol 217 ◽  
pp. 412-417
Author(s):  
X. Y. Xia ◽  
Z. Y. Huo ◽  
S. J. Xue
Keyword(s):  
Central Region ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Central Nucleus ◽  
Nuclear Region ◽  
Feedback Process ◽  
X Ray ◽  
The Galaxy ◽  
Low Metallicity ◽  
Gaseous Halo

We report on the properties of the hot gaseous halos of 10 nearby ultraluminous IRAS galaxies from Chandra observations. There exists diffuse soft X-ray emission surrounding the central nucleus within 10 kpc of the nuclear region with a temperature of about 0.7 keV and metallicity about Z ~ 1.0Z⊙. Also, emission lines from α elements and ions for are seen in all nearby ULIRGs in our sample. Outside the central region, the Chandra observations reveal a more extended hot gaseous halo with a temperature of about 0.6 keV and low metallicity (Z ~ 0.1Z⊙) for some of the ULIRGs. We discuss the nature and the implications of our results for the origin of X-ray halos in elliptical galaxies and the constraints this places on the feedback process.

scholarly journals X-Ray Superbubbles

1983 ◽  
Vol 6 ◽  
pp. 675-680
Author(s):  
Webster Cash
Keyword(s):  
Interstellar Medium ◽  
Collective Effects ◽  
Selection Effects ◽  
X Rays ◽  
High Quality ◽  
X Ray ◽  
Common Structure ◽  
The Galaxy ◽  
Gum Nebula

AbstractFour regions of the galaxy, the Cygnus Superbubble, the ƞ Carina complex, the Orion/Eridanus complex, and the Gum Nebula, are discussed as examples of collective effects in the interstellar medium. All four regions share certain features, indicating a common structure. We discuss the selection effects which determine the observable x-ray properties of the superbubbles and demonstrate that only a very few more in our galaxy can be detected in x-rays. X-ray observation of extragalactic superbubbles is shown to be possible but requires the capabilities of a large, high quality, AXAF class observatory.

scholarly journals New Spectral Observations of the Variable Galaxy Kaz 163

2013 ◽  
Vol 9 (S304) ◽  
pp. 39-40
Author(s):  
Emilia L. Karapetyan
Keyword(s):  
Elliptical Galaxy ◽  
Short Wave ◽  
Mean Value ◽  
Emission Lines ◽  
Byurakan Astrophysical Observatory ◽  
X Ray ◽  
Long Wave ◽  
The Galaxy ◽  
The Mean ◽  
Active Processes

AbstractKaz 163 is a close double galaxy. Its southern component S is compact, with a very blue nucleus, in which heated active processes take place. From time to time gas formations are ejected from it, which behave themselves like emission components around the main emission lines Hα and Hβ, around both from their long-wave and short-wave sides. This paper presents the spectral data of new observations, which were carried out with the 2.6m telescope at the Byurakan Astrophysical Observatory in September 2011. During the former observation in October 1981, lines [NII] λλ 6584,6548 were not visible in the spectrum of the component S. In 2001 they were already visible on the spectrum, and on the spectrum obtained in 2011 they already surpassed the intensity of Hα. The magnitude of the component S is also changing: its nucleus is very blue and its U-B = −0m.63. In the soft X-ray spectral range (0.1–2 keV) the flux of the radiation changed by 45% during 55,000 sec, and in the hard one (2–10keV) it changed up to 3.4 times. Photoindices Γ for the soft and hard ranges in the spectrum of galaxy S, unlike other objects, do not so much differ from each other. The mean value for the first interval is approximately 2.5 and is equal −2.0 for the second one. On the histogram of redshifts Kaz 163 corresponds to the first big peak of the distribution. It is concluded that the component S of the galaxy Kaz 163 is a NLS1 galaxy, with the development of their evolution, is in the preliminary stage. Component N is a normal elliptical galaxy with no activity.

scholarly journals Magnesium and silicon in interstellar dust: X-ray overview

2020 ◽  
Vol 641 ◽  
pp. A149
Author(s):  
D. Rogantini ◽  
E. Costantini ◽  
S. T. Zeegers ◽  
M. Mehdipour ◽  
I. Psaradaki ◽  
...  
Keyword(s):  
Cross Sections ◽  
Interstellar Dust ◽  
Galactic Centre ◽  
X Rays ◽  
Dust Grains ◽  
Large Reservoir ◽  
X Ray ◽  
Synchrotron Facility ◽  
The Galaxy ◽  
X Ray Binaries

Context. The dense Galactic environment is a large reservoir of interstellar dust. Therefore, this region represents a perfect laboratory to study the properties of cosmic dust grains. X-rays are the most direct way to detect the interaction of light with dust present in these dense environments. Aims. The interaction between the radiation and the interstellar matter imprints specific absorption features on the X-ray spectrum. We study them with the aim of defining the chemical composition, the crystallinity, and structure of the dust grains that populate the inner regions of the Galaxy. Methods. We investigated the magnesium and the silicon K-edges detected in the Chandra /HETG spectra of eight bright X-ray binaries, distributed in the neighbourhood of the Galactic centre. We modelled the two spectral features using accurate extinction cross-sections of silicates, which we measured at the synchrotron facility Soleil, France. Results. Near the Galactic centre, magnesium and silicon show abundances similar to the solar ones and they are highly depleted from the gas phase (δMg > 0.90 and δSi > 0.96). We find that amorphous olivine with a composition of MgFeSiO4 is the most representative compound along all lines of sight according to our fits. The contribution of Mg-rich silicates and quartz is low (less than 10%). On average we observe a percentage of crystalline dust equal to 11%. For the extragalactic source LMC X-1, we find a preference for forsterite, a magnesium-rich olivine. Along this line of sight we also observe an under-abundance of silicon ASi∕ALMC = 0.5 ± 0.2.

scholarly journals Modelling the Soft X-ray Excess in E1615+061

1994 ◽  
Vol 159 ◽  
pp. 317-317
Author(s):  
M. Bałucińska-Church ◽  
L. Piro ◽  
H. Fink ◽  
F. Fiore ◽  
M. Matsuoka ◽  
...  
Keyword(s):  
Power Law ◽  
Column Density ◽  
High Energy ◽  
X Rays ◽  
Hard Component ◽  
X Ray ◽  
Simple Power ◽  
High Energy Tail ◽  
Photon Index ◽  
Best Fit

SummaryWe report results of an international UV – X-ray campaign in 1990–1992 involving the IUE, Rosat and Ginga satellites to observe E1615+061, a Seyfert 1 galaxy with peculiar spectral and intensity behaviour over the last 20 years. The source has been found to be stable in its medium state during the observations. The Ginga (1–20 keV) spectrum of E1615+061 is adequately represented by a simple power law with a photon index α = 1.8 ± 0.1. However, α ∼ 2, as expected for the intrinsic power law component in a reflection model, cannot be ruled out statistically. The Rosat PSPC (0.1–2 keV) spectra collected during the All Sky Survey and the AO-1 phase can be well-described by a simple power law (α = 2.2 ± 0.1) with cold absorber (NH = 3.5 ± 0.3 · 10λ20 H/cmλ2). Both the photon index being significantly different than that obtained from the Ginga spectrum and the column density being smaller than the galactic column (NH ∼ 4.2 · 10λ20 H/cmλ2) give an indication of a soft excess over and above the hard component seen in the Ginga spectrum. E1615+061 has been observed with IUE in 1990 and in 1992. The source was stable and the colour excess E(B-V) derived from the data = 0.1 is in good agreement with that expected from the galactic absorption.To parameterise the soft excess we fitted the Rosat data with a two-component model consisting of a power law, and a blackbody or thermal bremsstrahlung, with a single galactic absorption term. The column density and the slope of the power law were kept constant. The blackbody temperature was 80 ± 6 eV and 63 ± 12 eV for photon index equal to 1.8 and 2.0, respectively, whereas the bremsstrahlung temperature was 220 ± 40 eV and 115 ± 30 eV for the two cases.An attempt to model the soft excess seen in the Rosat PSPC spectrum has been made assuming that the soft excess is the high energy tail of a disc spectrum which peaks in the UV part of the spectrum. Additionally it was assumed that there is a hard component contributing to the spectrum from UV to X-rays with parameters as described by the Ginga spectrum. The best fit parameters: the mass of the central source and the mass accretion rate were around 5 ± 1 · 10λ6 M⊙ and 0.2 ± 0.04 M⊙/yr, respectively.Our modelling shows that the soft X-ray excess can be described (χredλ2 < 1.2) as the high energy tail of an accretion disk spectrum if the intrinsic power law is quite steep (α = 2). The main contribution to the residuals in the Rosat PSPC range comes from 0.3–0.6 keV, with a tendency for these residuals to increase when the slope gets flatter. The accretion luminosity is ∼ 6.5 · 10λ44 erg/s for the best fit parameters, i.e. about the Eddington luminosity.

scholarly journals Kinematics of Supernova Remnants in the Galaxy and LMC

1983 ◽  
Vol 101 ◽  
pp. 295-298
Author(s):  
Peter Shull
Keyword(s):  
Supernova Remnants ◽  
Spectral Feature ◽  
Optical Emission ◽  
Emission Lines ◽  
Cygnus Loop ◽  
Interstellar Media ◽  
The Galaxy ◽  
Very High

The optical emission lines of six SNRs have been observed at very high angular and kinematic resolutions. Kinematic ion temperatures were derived, and evidence was found in shocked regions for Maxwellian microturbulence on scales ≤ 0.01 pc, and for non-Maxwellian macroturbulence on scales > 0.1 pc. The widths of shocked regions in the Cygnus Loop and the existence of three types of spectral feature in the LMC remnants are discussed in terms of SNR evolution in cloudy interstellar media.

Sign in / Sign up

Export Citation Format

Share Document