HIGH-RESOLUTION X-RAY SPECTROSCOPY OF THE MULTIPHASE INTERSTELLAR MEDIUM TOWARD Cyg X-2
Name
Yao_apj_696_2_1418.pdf
Size
629.21 KB
Format
Adobe PDF
Checksum (MD5)
e8315b9ab2ad4c0351e65e4fcd39c6fd
Author(s)
Schulz, Norbert S.
Gu, Ming F.
Nowak, Michael A.
Canizares, Claude R.
Date Issued
April 2009
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Citation
High-Resolution X-Ray Spectroscopy of the Multiphase Interstellar Medium Toward Cyg X-2
Yangsen Yao, Norbert. S. Schulz, Ming F. Gu, Michael A. Nowak, and Claude. R. Canizares 2009 ApJ 696 1418-1430 doi: 10.1088/0004-637X/696/2/1418. (C)2009 The American Astronomical Society.
Version
Final published version
Abstract
High-resolution X-ray absorption spectroscopy is a powerful diagnostic tool for probing chemical and physical properties of the interstellar medium (ISM) at various phases. We present detections of K transition absorption lines from the low-ionization ions of O I, O II, Ne I, Ne II, and Ne III, and the high-ionization ones of O VI, O VII, O VIII, Ne IX, and Mg XI, as well as details of neutral absorption edges from Mg, Ne, and O in an unprecedented high-quality spectrum of the low-mass X-ray binary Cyg X-2. These absorption features trace the intervening ISM which is indicated by the unshifted line centroids with respect to the rest-frame wavelengths of the corresponding atomic transitions. We have measured the column densities of each ion. We complement these measurements with the radio H I and optical Hα observations toward the same sight line and estimate the mean abundances of Ne, O, and Mg in the cool phase to Ne/H = 0.84(+0.13) –0.10 × 10(–4), O/H = 3.83(+0.48) –0.43 × 10(–4), and Mg/H = 0.35(+0.09) –0.11 × 10(–4), and O and Mg in the hot phase to O/H = 5.81(+1.30) –1.34 × 10(–4) and Mg/H = 0.33(+0.09) –0.09 × 10(–4), respectively. These results indicate a mild depletion of oxygen into dust grains in the cool phase and little or no depletion of magnesium. We also find that absorption from highly ionized ions in the hot Galactic disk gas can account for most of the absorption observed toward the extragalactic sight lines like Mrk 421. The bulk of the observed O VI likely originates from the conductive interfaces between the cool and hot gases, from which a significant amount of N V and C IV emission is predicted.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
http://dx.doi.org/10.1088/0004-637X/696/2/1418
