Date : 6/20 (Wed) [15:00 - ] @F313
Speaker: Dr. Shingo Hirano (Kyushu University)
Title : Formation of first stars with ten to one million solar masses
Abstract: First stars (Population III stars) play vital roles in the early cosmic evolution by initiating cosmic reionization and chemical enrichment of the intergalactic medium. The characteristic mass of first stars and its initial mass function are thus essential to understand the formation and evolution of the first galaxy, one of the important observational targets by the next-generation telescopes. The numerous theoretical/numerical works suggest various paths of first star formation and final masses depending on the star-forming environment properties. A large cosmological sample of first star formation shows a wide range of stellar masses from 10 to 1000 Msun depending on the properties of star-forming gas cloud. Under a quite limited condition, very massive first stars can form with 1e5-1e6 Msun and leave a promising seed for the formation of observed high-z quasars. Furthermore, a recent study shows the formation of the first star clusters and massive star binaries. The eventual formation of the remnant black holes will leave a close binary of massive black holes, which can be a progenitor of strong gravitational wave sources. This talk will introduce these latest results and prospects on the formation theory of first stars.

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