Where are all the baryons in the universe?

日期:2020-10-21 阅读:916


Studies have shown that stars contain very little baryonic matter and that the majority of the baryons in the universe likely exist in gaseous form. Cold baryons are more easily observed, but what have been seen cannot account for the expected number of baryons produced in the early universe. The lack of understanding of the distribution and properties of “missing” baryons is impeding the progress in advancing the theory of galaxy formation and evolution. The bulk of the “missing baryons” may be exist in the form of hot, extended halos around galaxies and/or filamentary structures in the cosmic web; recent observations seem to support such scenarios. However, due to the lack of a sensitive probe, the physical and chemical properties of hot baryons are poorly measured with existing facilities, but carry critical information on the feedback processes that are deemed critical to galaxy evolution. Theory is far ahead of observation in this area; data are severely lacking


Prof. Cui carries out research in the general areas of high energy astrophysics and particle astrophysics. At present the science topics of particular interest include: (1) mass accretion and particle acceleration in microquasars and AGN; and (2) warm-hot phases of interstellar, circumgalactic, and intergalactic media. He has played key roles in the development of the Rossi X-ray Timing Explorer (RXTE) satellite and the Very Energetic Radiation Imaging Telescope Array (VERITAS) observatory, and is involved in the formulation of several mission concepts. In particular, he presently leads R&D efforts for the Hot Universe Baryon Surveyor (HUBS), which aims at finding “missing baryons” in circumgalactic and intergalactic media via high throughput, high-resolution X-ray spectroscopy.


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