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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 @).

November 20, Tuesday at 11:00 am

" The build-up of the red sequence "

Masayuki Tanaka (ESO)


We discuss the environmental dependence of galaxy colors at z<1.3 and show that galaxies follow the "environment-dependent down-sizing" evolution. We suggest that galaxy-galaxy interactions may be the primary driver of this evolution.
We are conducting a panoramic imaging and spectroscopic survey of galaxy clusters at 0.5 What physical process(es) drives the observed build-up of the red sequence? We address this question with composite spectra of red galaxies in field, group, and cluster environments at z<0.83. Red galaxies in groups at z~0.8 and in the field z~0.5 show strong Hd absorptions for their colors. Interestingly, these are the environments in which we observe the on-going build-up of the red sequence. The strong Hd absorptions imply that their star formation rates decreased on a relatively short time scale (<1Gyr). We suggest that galaxy-galaxy interactions are likely the driving process of the truncation of the star formation activities and the build-up of the red sequence.

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

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