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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tomonori Usuda, Kumiko S. Usuda, Masayuki Akiyama) by email : (please change"_at" to @).

April 23, Monday at 11:00 am

" A Subaru Search for Population III Stars in High-z Universe "

Tohru Nagao


The detection and observational investigation of the first population of stars (Population III stars; hereafter PopIII), formed from the primordial un-enriched gas, will be the one of the main goals of observational astronomy in the next decade. The discovery of PopIII objects will open a new window to study the early forming phase of galaxies, the environment and mechanism responsible for the production of the first metals, and their implications for the reionization of the universe.
Galaxies hosting a significant fraction of massive PopIII objects are expected to show huge equivalent widths of Ly_alpha and moderately strong HeII emission, due to the very hard SED of their ionizing photons. To search for such interesting objects, we developed a new selection method to pick up objects with a large Ly_alpha equivalent width effectively at 6.0 < z < 6.5, and applied this method to the wide and deep imaging data of the Subaru Deep Field project. We identified 7 photometric candidates as galaxies having such a large Ly_alpha equivalent width at z>6, and spectroscopically confirmed at least 5 objects among the seven candidates. We tried to detect HeII emission from one of those objects through ultra-deep near-IR spectroscopy, which resulted in obtaining upper limit on SFR(PopIII).
In this seminar, I report our recent studies described above, and will briefly mention on our on-going trials to discover massive PopIII stars in high-z universe.

Seminars are also held at JAC, CFHT, and IfA.

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