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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 : sseminar_at_subaru.naoj.org (please change"_at" to @).
April 23, Monday at 11:00 am
" A Subaru Search for Population III Stars in High-z Universe "
Tohru Nagao
(NAOJ)
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.