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Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

University of Massachusetts Amherst

2003

Methods : numerical

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Full-Text Articles in Physical Sciences and Mathematics

X-Ray Absorption By The Low-Redshift Intergalactic Medium: A Numerical Study Of The Lambda Cold Dark Matter Model, Xl Chen, Dh Weinberg, N Katz, R Dave Jan 2003

X-Ray Absorption By The Low-Redshift Intergalactic Medium: A Numerical Study Of The Lambda Cold Dark Matter Model, Xl Chen, Dh Weinberg, N Katz, R Dave

Astronomy Department Faculty Publication Series

Using a hydrodynamic simulation of a cold dark matter universe with a cosmological constant, we investigate the "X-ray forest" absorption imprinted on the spectra of background quasars by the intervening intergalactic medium (IGM), at redshift z 0. In agreement with previous studies, we find that O VII and O VIII produce the strongest absorption features. The strong oxygen absorbers that might be detectable with Chandra or XMM-Newton arise in gas with T ~ 105.5-106.5 K and overdensities δ 100 that are characteristic of galaxy groups. Future X-ray missions could detect weaker oxygen absorption produced by gas with …


The Influence Of Omega(B) On High-Redshift Structure, Jp Gardner, N Katz, L Hernquist, Dh Weinberg Jan 2003

The Influence Of Omega(B) On High-Redshift Structure, Jp Gardner, N Katz, L Hernquist, Dh Weinberg

Astronomy Department Faculty Publication Series

We analyze high-redshift structure in three hydrodynamic simulations that have identical initial conditions and cosmological parameters and differ only in the value of the baryon density parameter, Ωb = 0.02, 0.05, and 0.125. Increasing Ωb does not change the fraction of baryons in the diffuse (unshocked) phase of the intergalactic medium, but it increases cooling rates and therefore transfers some baryons from the shocked intergalactic phase to the condensed phase associated with galaxies. Predictions of Lyα forest absorption are almost unaffected by changes in Ωb at velocity scales greater than 5 km s-1 (our resolution limit), …