Constraining the Properties of OVI in the 0.4

Type Conference Paper
Names Ben Rosenwasser, S. Muzahid, J. Norris, J. C. Charlton, P. Rodriguez Hidalgo, B. P. Wakker, A. Narayanan, T. Misawa, C. W. Churchill, N. Mathes, N. Nielsen, R. Ganguly
Proceedings Title American Astronomical Society
Conference Name AAS Meeting #223, #458.02
Date January 1, 2014
Library Catalog
Abstract The Circumgalactic Medium (CGM), the interface between galactic halos and the intergalactic medium, traces the evolution of gas flows into and out of galaxies. The study of the CGM provides important insight into the physical processes and evolution of galaxies. We can probe the tenuous CGM by studying intervening absorption lines in the spectra of quasars. Analyzing diagnostic lines that span a range of ionization levels (MgII, CII, SiIV, CIV, OVI) reveals the nature of these unilluminated environments. Studying the highly-ionized OVI ion is important for understanding the lowest density region of the CGM. We present a study of the absorption properties of ten intermediate redshift (0.4 < z < 1.0) MgII absorbers for which high resolution absorption profiles are available for low, intermediate, and high ionization metal-line transitions, as well as for HI. OVI is detected in six of the systems. We have carried out CLOUDY photoionization modeling of each of the systems to constrain the metallicities and infer ionization conditions for low and high ionization gas phases. We find varying, complex relationships between the mid- and high-ionization ions, namely SiIV, CIV, and OVI. OVI is not detected for a weak MgII absorber nor for a satellite around a strong MgII absorber, which may suggest these systems are not analogs of Milky Way HVCs. Our study helps elucidate the physical conditions of OVI absorption in a redshift range that has previously been, to a large extent, unobserved.
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