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Observations of Diffuse Emission from the Hot ISM

Published online by Cambridge University Press:  12 April 2016

W.T. Sanders  and
R.J. Edgar
W.T. Sanders
Affiliation:
Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706, USA Space Science & Engineering Center, University of Wisconsin-Madison, 1225 W. Dayton Street, Madison, WI 53706, USA
R.J. Edgar
Affiliation:
Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706, USA Space Science & Engineering Center, University of Wisconsin-Madison, 1225 W. Dayton Street, Madison, WI 53706, USA

Abstract

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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.

Type
V. The Interstellar Medium and Diffuse Background
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 269 - 275
Copyright
Copyright © Kluwer 1996

References

Benjamin, R.A., Venn, K.A., Hiltgen, D.D., & Sneden, C. 1995, The Distance to an X-Ray Shadowing Molecular Cloud in Ursa Major. ApJ, submittedGoogle Scholar
Bloch, J.J., Jahoda, K., Juda, M., McCammon, D., Sanders, W.T., & Snowden, S.L. 1986, Observations of the Soft X-Ray Background at 0.1 keV, ApJ, 308, L59–L62 Google Scholar
Bowyer, C.S., Field, G.B., & Mack, J.E. 1968, Detection of an Anisotropic Soft X-ray Background Flux, Nature, 217, 32 Google Scholar
Burrows, D.N., & Mendenhall, J.A. 1991, Soft X-ray Shadowing by the Draco Cloud, Nature, 351, 629 Google Scholar
Dickey, J. & Lockman, F.J. 1990, H I in the Galaxy, Ann. Rev. Astr. Ap., 28, 215 CrossRefGoogle Scholar
Edgar, R.J. & Cox, D.P. 1993, Hot Bubbles in a Magnetic Interstellar Medium: Another Look at the Soft X-ray Background, ApJ, 413, 190 Google Scholar
Edwards, B.C. 1990, Observations of the Soft X-ray Background, PhD Thesis, University of Wisconsin, Madison Google Scholar
Garmire, G.P., Apparao, K.M.V., Burrows, D.N., Fink, R.L., & Kraft, R.P. 1992, The Soft X-ray Diffuse Background Observed with the HEAO 1 Low-Energy Detectors, ApJ, 399, 694 Google Scholar
Juda, M., Bloch, J.J., Edwards, B.C., McCammon, D., Sanders, W.T., Snowden, S.L., & Zhang, J. 1991, Limits on the Density of Neutral Gas within 100 Parsecs from Observations of the Soft X-Ray Background, ApJ, 367, 182 Google Scholar
Marshall, F.J. & Clark, G.W. 1984, SAS & Survey of the Soft X-ray Background, ApJ, 287, 633 Google Scholar
McCammon, D., Burrows, D.N., Sanders, W.T., & Kraushaar, W.L. 1983, The Soft X-Ray Background, ApJ, 269, 107 Google Scholar
Sanders, W.T., Edgar, R.J., Juda, M., Kraushaar, W.L., McCammon, D., Snowden, S.L., Zhang, J., & Skinner, M.A. 1992, The Diffuse X-ray Spectrometer Experiment, Proceeding of the SPIE: EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy III, 1743, 60 Google Scholar
Snowden, S.L., Cox, D.P., McCammon, D., & Sanders, W.T. 1990, A Model for the Distribution of Material Generating the Soft X-Ray Background, ApJ, 354, 211 Google Scholar
Snowden, S.L., Mebold, U., Hirth, W., Herbstmeier, U., & Schmitt, J.H.M.M. 1991, ROSAT Detection of an X-ray Shadow in the ¼ keV Diffuse Background in the Draco Nebula, Science, 252, 1529 Google Scholar
Snowden, S.L. 1993, Implications of ROSAT Observations for the Local Hot Bubble, Adv. Space Res., 13(12), 103–111 Google Scholar
Snowden, S.L., McCammon, D., & Verter, F. 1993, The X-ray Shadow of the High-Latitude Molecular Cloud MBM 12, ApJ, 409, L21–L24 Google Scholar
Snowden, S.L., Hasinger, G., Jahoda, K., Lockman, F.J., McCammon, D., & Sanders, W.T. 1994, Soft X-Ray and H I Surveys of the Low N H Region in Ursa Major, ApJ, 430, 601 Google Scholar
Snowden, S.L., Freyberg, M.J., Plucinsky, P.P., Schmitt, J.H.M.M., Trümper, J., Voges, W., Edgar, R.J., McCammon, D., & Sanders, W.T. 1995, First Maps of the Soft X-ray Diffuse Background from the ROSAT XRT/PSPC All-Sky Survey, ApJ, submittedGoogle Scholar