Studying the warm-hot intergalactic medium in emission

Y. Takei, E. Ursino, E. Branchini, T. Ohashi, H. Kawahara, K. Mitsuda, L. Piro, A. Corsi, L. Amati, J. W. Den Herder, M. Galeazzi, J. Kaastra, L. Moscardini, F. Nicastro, F. Paerels, M. Roncarelli, M. Viel

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25 Scopus citations


We assess the possibility of detecting the warm-hot intergalactic medium in emission and characterizing its physical conditions and spatial distribution through spatially resolved X-ray spectroscopy, in the framework of the recently proposed DIOS, EDGE, Xenia, and ORIGIN missions, all of which are equipped with microcalorimeter-based detectors. For this purpose, we analyze a large set of mock emission spectra, extracted from a cosmological hydrodynamical simulation. These mock X-ray spectra are searched for emission features showing both the O VII Kα triplet and O VIII Lyα line, which constitute a typical signature of the warm-hot gas. Our analysis shows that 1 Ms long exposures and energy resolution of 2.5 eV will allow us to detect about 400 such features per deg2 with a significance ≥5σ and reveals that these emission systems are typically associated with density ∼100 above the mean. The temperature can be estimated from the line ratio with a precision of ∼20%. The combined effect of contamination from other lines, variation in the level of the continuum, and degradation of the energy resolution reduces these estimates. Yet, with an energy resolution of 7 eV and all these effects taken into account, one still expects about 160 detections per deg2. These line systems are sufficient for tracing the spatial distribution of the line-emitting gas, which constitute an additional information, independent from line statistics, to constrain the poorly known cosmic chemical enrichment history and the stellar feedback processes.

Original languageEnglish
Article number91
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 10 2011


  • X-rays: diffuse background
  • cosmology: observations
  • intergalactic medium
  • large-scale structure of universe


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