BRINGING SIMULATION AND OBSERVATION TOGETHER TO BETTER UNDERSTAND THE INTERGALACTIC MEDIUM

Hilary Egan*, Britton D. Smith, Brian W. O'Shea, J. Michael Shull

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The methods by which one characterizes the distribution of matter in cosmological simulations is intrinsically different from how one performs the same task observationally. In this paper, we make substantial steps toward comparing simulations and observations of the intergalactic medium (IGM) in a more sensible way. We present a pipeline that generates and fits synthetic QSO absorption spectra using sight lines cast through a cosmological simulation, and simultaneously identifies structure by directly analyzing the variations in Hi and Ovi number density. We compare synthetic absorption spectra with a less observationally motivated, but more straightforward density threshold-based method for finding absorbers. Our efforts focus on Hi and Ovi to better characterize the warm/hot IGM, a subset of the IGM that is challenging to conclusively identify observationally. We find that the two methods trace roughly the same quantities of Hi and Ovi above observable column density limits, but the synthetic spectra typically identifymore substructure in absorbers. We use bothmethods to characterize Hi and Ovi absorber properties. We find that both integrated and differential column density distributions from both methods generally agree with observations. The distribution of Doppler parameters between the two methods are similar for Lya and compare reasonably with observational results, but while the two methods agree with each other with Ovi systems, they both are systematically different from observations. We find a strong correlation between Ovi baryon fraction and Ovi column density. We also discuss a possible bimodality in the temperature distribution of the gas traced by Ovi.

Original languageEnglish
Article number64
Number of pages17
JournalAstrophysical Journal
Volume791
Issue number1
DOIs
Publication statusPublished - 10 Aug 2014

Keywords

  • cosmology: observations
  • intergalactic medium
  • methods: numerical
  • quasars: absorption lines
  • ultraviolet: general
  • LY-ALPHA FOREST
  • O-VI ABSORPTION
  • PHYSICAL CONDITIONS
  • BARYON CONTENT
  • IONIZED-GAS
  • ABSORBERS
  • OVI
  • UNIVERSE
  • LINES
  • SPECTROGRAPH

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