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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 @).

May 15, Tuesday at 11:00 am

" The Galaxy Luminosity Functions down to M~-10 in the Hydra I Cluster "

Hitomi Yamanoi

(Grad. Univ. Advanced Studies)

Dwarf galaxies account for a large share of cluster galaxies and should be closely related to the formation and evolution of clusters. Despite the obvious importance, however, the number of very faint (douwn to M~-10) cluster samples available to date is limited and properties of such faint galaxies remain unclear. In order to reveal properties of faint cluster dwarfs, we derive very faint-end slopes of the galaxy luminosity functions (LFs) in the Hydra I cluster at z=0.0126, for which such a very faint galaxy population, at M~-10, has not been previonsly surveyed. We find that the LF of the entire population has a slightly steeper slope (alpha~-1.6) in the range of -20 < M < -10 than those reported for other clusters in slightly brighter ranges. The LF shows a significant upturn at M~-16 as is seen in several other nearby clusters, but not in the field. We also find that red galaxies dominate over blue galaxies in the Hydra I down to M=-10. The upturn in the faint-end slope of the LF is likely due to the generation of the faint red galaxies, which presumably related to cluster environments. Strong tidal interactions (such as harassment) should occure frequently in clusters, and many galaxies are probably transformed into red galaxies, which possibly form the observed upturn. In this talk, I will present our results of LFs in the two different regions of the Hydra I in B- and Rc-bands using the Subaru Suprime-Cam photometry.

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

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