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Metal-absorption column densities in fast radiative shocks

Orly, Gnat and Amiel, Sternberg (2009) Metal-absorption column densities in fast radiative shocks. Astrophysical Journal, 693 (2). pp. 1514-1542. ISSN 0004-637X.

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In this paper, we present computations of the integrated metal-ion column densities produced in the postshock cooling layers behind fast, radiative shock waves. For this purpose, we have constructed a new shock code that calculates the nonequilibrium ionization and cooling, follows the radiative transfer of the shock self-radiation through the postshock cooling layers, takes into account the resulting photoionization and heating rates, follows the dynamics of the cooling gas, and self-consistently computes the initial photoionization state of the precursor gas. We discuss the shock structure and emitted radiation, and study the dependence on the shock velocity, magnetic field, and gas metallicity. We present a complete set of integrated postshock and precursor metal-ion column densities of all ionization stages of the elements H, He, C, N, O, Ne, Mg, Si, S, and Fe, for shocks with velocities of 600 and ~2000 km s^–1, corresponding to initial postshock temperatures of 5 × 10^6 and 5 × 10^7 K, cooling down to 1000 K. We consider shocks in which the magnetic field is negligible (B = 0) so that the cooling occurs at approximately constant pressure ("isobaric"), and shocks in which the magnetic pressure dominates everywhere such that the cooling occurs at constant density (isochoric). We present results for gas metallicities Z ranging from 10^–3 to twice the solar abundance of heavy elements, and we study how the observational signatures of fast radiative shocks depend on Z. We present our numerical results in convenient online figures and tables.

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Additional Information:© 2009 The American Astronomical Society. Received 2008 September 9; accepted 2008 December 9; published 2009 March 9. We thank Gary Ferland for his invaluable assistance in our nonstandard use of Cloudy. We thank Hagai Netzer for generously providing us with his up-to-date Ion atomic data set. We thank Chris McKee, Re’em Sari, and Ehud Nakar for many helpful discussions. Our research is supported by the US– Israel Binational Science Foundation (grant 2002317). O.G. acknowledges support provided by NASA through Chandra Postdoctoral Fellowship grant number PF8-90053 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060.
Funding AgencyGrant Number
US-Israel Binational Science Foundation2002317
NASA through Chandra Postdoctoral FellowshipPF8-90053
Subject Keywords:atomic processes; intergalactic medium; ISM: general; plasmas; quasars: absorption lines; shock waves
Issue or Number:2
Record Number:CaltechAUTHORS:20090420-100932508
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14026
Deposited By: Tony Diaz
Deposited On:20 Apr 2009 21:00
Last Modified:03 Oct 2019 00:46

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