Observations of the MIssing Baryons in the warm-hot intergalactic medium

摘要: It has been known for decades that the observed number of baryons in local universe falls about 30-40% short total predicted by Big-Bang Nucleosynthesis, as inferred from density fluctuations Cosmic Microwave Background and seen during first 2-3 billion years so called Lyman-alpha Forest. A theoretical solution to this paradox locates missing hot tenuous filamentary gas between galaxies, warm-hot intergalactic medium. However, it is difficult detect them there because largest far constituent - hydrogen mostly ionized therefore almost invisible far-ultraviolet spectra with typical signal-to-noise ratios. Indeed, despite large observational efforts, only a few marginal claims detection have made far. Here we report observations two absorbers highly oxygen (OVII) high signal-to-noise-ratio X-ray spectrum quasar at redshift >0.4. These show no variability over 2-year timescale associated cold absorption, making assumption they originate quasar's intrinsic outflow or host galaxy's interstellar medium implausible. The OVII systems lie regions characterized (x4 compared average) galaxy over-densities their (down sensitivity threshold our data), agrees well numerical simulation predictions long-sought (WHIM). We conclude found.