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 Evolution and State of the Local ISM

1996 ◽  
Vol 171 ◽  
pp. 442-442
Author(s):  
T. Schmutzler ◽  
D. Breitschwerdt
Keyword(s):  
Basic Feature ◽  
Emission Lines ◽  
Continuum Emission ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Self Consistent ◽  
X Ray Background ◽  
Collisional Ionization ◽  
Consistent Approach ◽  
The Continuum

The most puzzling observations concerning the LISM (distance < 100 pc) can be explained by a fast adiabatically cooled gas in the cavity of an old superbubble. The ultrasoft X-ray background and contributions to the C- and M-bands are due to the continuum emission of delayed recombination [1]. In contrast to collisional ionization equilibrium (CIE) models, but consistent with recent observations [2], our model predicts a lack of emission lines and a low emissivity in the EUV range. In the figure below we compare the emissivities resulting from CIE at T = 106 K and those from our model at T = 4.2 × 104 K. The basic feature of our model is a thermally self-consistent approach of the time-dependent evolution.

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.

An Einstein survey of the 1 keV soft X-ray background in the Galactic plane

1994 ◽  
Vol 424 ◽  
pp. 671
Author(s):  
John M. Stanford ◽  
Jean-Pierre Caillault
Keyword(s):  
Galactic Plane ◽  
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 Modeling the Local Bubble

1997 ◽  
Vol 166 ◽  
pp. 121-131 ◽  
Author(s):  
Donald P. Cox
Keyword(s):  
Solar System ◽  
Facial Expressions ◽  
Simplified Model ◽  
Observational Constraints ◽  
Local Bubble ◽  
Interstellar Absorption ◽  
Modeling Effort ◽  
X Ray ◽  
Idealized Modeling ◽  
X Ray Background

AbstractModeling the Local Bubble is one of those activities fraught with danger. It is very easy to be too naive, to fail to consider the dependence of the model on assumptions about the nearby ambient state, or the likelihood of such a structure. It is similarly easy to become so caught up in the details of the vicinity that it is unclear where to begin a necessarily idealized modeling effort. And finally, it is important to remember that the data we have may in some cases be lying to us, and that we have not yet learned to read their facial expressions quite carefully enough.That said, I’ve tried in this paper to be helpful to those who may wish to take the risks. I surveyed the very most basic stories that the data seem to tell, and pointed out the standard coincidences that may be telling us a lot about what is happening, but may turn out once again to have been just coincidences. I’ve described 5 distinct conceptions that in one flavor or another pretty well survey the collection of mental images that have so far been carried by those who’ve attempted models. One may be right, or something entirely different may be more appropriate. It’s at least vital to realize that a conception comes first, followed by a simplified model of details. I’ve also included a long list of questions directed at observers. Some have partial answers, some one wouldn’t know today quite how to approach. But it is a list that students of the soft x-ray background, interstellar absorption lines, possible instrumentation, and the heliosphere may wish to review from time to time, just to see whether they can figure out how to be more helpful. There is another list for modelers, things the models must address, however-so-flimsily if necessary, because there are strong observational constraints (and stronger ones coming) on what can and cannot be present in the local ISM. To that I’ve added a few remarks concerning x-ray emission coming from beyond the Local Bubble, and another few on how x-ray emission from within the solar system might be contaminating what we see. That last bit is new, exciting, and possibly wrong, but it is an example of the ongoing wariness I believe one has to take toward the facts in the case. By the way, Dieter, it really was a great meeting.

scholarly journals Magnetic Reconnection as the Origin of Galactic Ridge X-Ray Emission

1998 ◽  
Vol 188 ◽  
pp. 269-270 ◽  
Author(s):  
S. Tanuma ◽  
T. Yokoyama ◽  
T. Kudoh ◽  
K. Shibata ◽  
R. Matsumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Galactic Plane ◽  
Thermal Emission ◽  
Mhd Equations ◽  
Magnetic Islands ◽  
Cool Component ◽  
X Ray ◽  
Hot Plasma ◽  
Helical Tubes

We present a scenario for the origin of the hot plasma in our Galaxy, as a model of a strong X-ray emission (LX(2 – 10keV) ~ 1038 erg s−1), called Galactic Ridge X-ray Emission (GRXE), which has been observed near the Galactic plane. GRXE is thermal emission from hot component (~ 7 keV) and cool component (~ 0.8 keV). Observations suggest that the hot component is diffuse, and is not escaping away freely. Both what heats the hot component and what confines it in the Galactic ridge are still remained puzzling, while the cool component is believed to be made by supernovae. We propose a new scenario: the hot component of GRXE plasma is heated by magnetic reconnection, and confined in the helical magnetic field produced by magnetic reconnection or in the current sheet and magnetic field. We solved also the 2-dimensional magnetohydrodynamic (MHD) equations numerically to study how the magnetic reconnection creates hot plasmas and magnetic islands (helical tubes), and how the magnetic islands confine the hot plasmas in Galaxy. We conclude that the magnetic reconnection is able to heat up the cool component to hot component of GRXE plasma if the magnetic field is localized into intense flux tube with Blocal ~ 30 μG (the volume filling factor of f ~ 0.1).

scholarly journals Intensity Variations of the Soft X-ray Background: the Boundary Structure of the Local Hot Bubble at Low Galactic Latitudes

1997 ◽  
Vol 166 ◽  
pp. 325-328
Author(s):  
S. Park ◽  
J.P. Finley ◽  
S.L. Snowden
Keyword(s):  
Spatial Structure ◽  
Galactic Plane ◽  
Boundary Structure ◽  
X Ray ◽  
X Ray Background

Abstract42 ROSAT PSPC pointed observations in the Galactic plane (l ~ 4° – 26°) are mosaicked in order to study the spatial structure of the X-ray emitting gas in the Local Hot Bubble (LHB). Degree scale X-ray intensity variations are detected at the ±10% level in the ¼ keV band, which imply a likely influence from a clumpy boundary shell of the LHB in the observed ¼ keV band X-ray background. The possible origins of such a clumpy boundary structure of the LHB are discussed.

scholarly journals Swift/XRT Deep Galactic Plane Survey Discovery of a New Intermediate Polar Cataclysmic Variable, Swift J183920.1-045350

2021 ◽  
Vol 923 (2) ◽  
pp. 243
Author(s):  
Nicholas M. Gorgone ◽  
Patrick A. Woudt ◽  
David Buckley ◽  
Koji Mukai ◽  
Chryssa Kouveliotou ◽  
...  
Keyword(s):  
Orbital Period ◽  
Galactic Plane ◽  
Emission Lines ◽  
Cataclysmic Variable ◽  
Optical Photometry ◽  
X Ray ◽  
Common Features ◽  
Spin Period ◽  
Long Baseline

Abstract We report on the Swift/XRT Deep Galactic Plane Survey discovery and multiwavelength follow-up observations of a new intermediate polar (IP) cataclysmic variable, Swift J183920.1-045350. A 449.7 s spin period is found in XMM-Newton and NuSTAR data, accompanied by a 459.9 s optical period that is most likely the synodic, or beat period, produced from a 5.6 hr orbital period. The orbital period is seen with moderate significance in independent long-baseline optical photometry observations taken with the ZTF and SAAO telescopes. We find that the X-ray pulse fraction of the source decreases with increasing energy. The X-ray spectra are consistent with the presence of an Fe emission line complex with both local and interstellar absorption. In the optical spectra, strong Hα, H i, He i, and He ii emission lines are observed, all common features in magnetic CVs. The source properties are thus typical of known IPs, with the exception of its estimated distance of 2.26 − 0.83 + 1.93 kpc, which is larger than typical, extending the reach of the CV population in our Galaxy.

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