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Colloquium by Wei Cui (Purdue University)

Hunting for Cosmic Baryons

Abstract: 

One of the triumphs of the Big Bang Nucleosynthesis (BBN) theory is that its  predicted abundances of  primordial isotopes agree with the measured values.  Moreover, the predicted baryonic mass is accounted for at high redshifts  observationally. Going towards low redshifts, however, only a fraction of the BBN  baryons are detected; this is the “missing baryon” problem. The common wisdom  is that those baryons are not missing, but are hidden in some warm-hot gas of  very low density, which is difficult to detect; cosmological simulations support this  view. Such gas may be “seen” through the emission or absorption lines of its  highly ionized constituents. For that, an X-ray spectrometer of high throughput  and high resolution would likely be required. I will describe the development of  microcalorimeters for X-ray spectroscopy. I will also briefly discuss the design of  a satellite experiment that employs the microcalorimeters to carry out a survey of  warm-hot gas in the universe, addressing a wide range of  important issues in  astrophysics, including the “missing baryon” problem.

Time: May 04, 2016, 2:30 pm

Venue: A601, NAOC