Spectroscopy of the WHIM with the Cosmic Origins Spectrograph

Type Conference Paper
Names Yangsen Yao, J. M. Shull, C. W. Danforth, B. A. Keeney, J. Stocke, B. D. Savage, A. Narayanan
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #215, #464.01
Volume 42
Pages 498
Date January 1, 2010
URL http://adsabs.harvard.edu/abs/2010AAS...21546401Y
Library Catalog NASA ADS
Abstract The tenuous warm-hot intergalactic medium (WHIM) at temperatures of 105--107 K is believed to contain a significant amount of baryonic matter in the local universe. But its properties (for instance, density, temperature, and ionization stage) are still poorly understood. With the unprecedented detection sensitivity and broad coverage in far-ultraviolet and near-ultraviolet wavelengths, the Cosmic Origins (COS) Spectrograph aboard Hubble Space Telescope now allows us to detect absorption lines of Ne VIII, O VI, N V, and C IV, as well as low ionization ions produced in the WHIM at the same time. It thus offers us a unique opportunity to probe the WHIM properties via powerful diagnostic of spectroscopy. We herein present a hybrid model that accounts for both photoionization and collisional ionization in the WHIM and utilizes the diagnostic power of multiple absorption lines to constrain the WHIM properties. We apply this model to several WHIM absorbers where the COS observations are available.
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