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Partially Cooled Shocks: Detectable Precursors in the Warm/hot Intergalactic Medium

Gnat, Orly (2011) Partially Cooled Shocks: Detectable Precursors in the Warm/hot Intergalactic Medium. Astrophysical Journal, 729 (2). Art. No. 82. ISSN 0004-637X.

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I present computations of the integrated column densities produced in the post-shock cooling layers and in the radiative precursors of partially cooled fast shocks as a function of the shock age. The results are applicable to the shock-heated warm/hot intergalactic medium which is expected to be a major baryonic reservoir and contain a large fraction of the so-called missing baryons. My computations indicate that readily observable amounts of intermediate and high ions, such as C IV, N V, and O VI, are created in the precursors of young shocks, for which the shocked gas remains hot and difficult to observe. I suggest that such precursors may provide a way to identify and estimate the "missing" baryonic mass associated with the shocks. The absorption-line signatures predicted here may be used to construct ion-ratio diagrams, which will serve as diagnostics for the photoionized gas in the precursors. In my numerical models, the time evolution of the shock structure, self-radiation, and associated metal-ion column densities are computed by a series of quasi-static models, each appropriate for a different shock age. The shock code used in this work calculates the non-equilibrium ionization and cooling, follows the radiative transfer of the shock self-radiation through the post-shock cooling layers, takes into account the resulting photoionization and heating rates, follows the dynamics of the cooling gas, and self-consistently computes the photoionization states in the precursor gas. I present a complete set of the age-dependent post-shock and precursor columns for all ionization states of the elements H, He, C, N, O, Ne, Mg, Si, S, and Fe as functions of the shock velocity, gas metallicity, and magnetic field. I present my numerical results in convenient online tables.

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Additional Information:© 2011 American Astronomical Society. Received 2010 November 22; accepted 2010 December 30; published 2011 February 11. My research is supported by NASA through Chandra Postdoctoral Fellowship grant PF8-90053 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-0306.
Funding AgencyGrant Number
NASA Chandra Postdoctoral FellowshipPF8-90053
Smithsonian Astrophysical Observatory (SAO)NAS8-0306
Subject Keywords:atomic processes; intergalactic medium; ISM: general; plasmas; quasars: absorption lines; shock waves
Issue or Number:2
Classification Code:PACS: 98.62.Ra; 95.30.Jx; 95.30.Ft
Record Number:CaltechAUTHORS:20110411-105659682
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Official Citation:Partially Cooled Shocks: Detectable Precursors in the Warm/hot Intergalactic Medium Orly Gnat 2011 ApJ 729 82
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23275
Deposited By: Jason Perez
Deposited On:12 Apr 2011 14:37
Last Modified:03 Oct 2019 02:45

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