Subaru Seminars



This Month






Site Map

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 (Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi) by email : (please change"_at" to @).

May 10, Tuesday, 11:00 am in 104

" Isophote Shapes of Early-Type Galaxies in Massive Clusters at z ~ 1 and 0 "

Kazuma Mitsuda

(Univerisyt of Tokyo)

We compare the isophote shape parameter a4 of early-type galaxies (ETGs) between z~1 and 0 as a proxy for dynamics to investigate when the dynamical properties of ETGs are characterized. We create cluster ETG samples with spectroscopic redshifts from the Hubble Space Telescope Cluster Supernova Survey for z~1 and the Sloan Digital Sky Survey for z~0. We have developed an isophote shape analysis method which can be used for high-redshift galaxies and applied the same method for both the z~1 and 0 samples. We find similar dependence of the a4 parameter on the mass and size at z~1 and 0; the main population of ETGs changes from disky to boxy at a critical stellar mass of log(M*/M_sun)~11.5 with the massive end dominated by boxy. The similar critical mass between these redshifts is consistent with a scenario that the mass quenching is the origin of massive boxy ETGs. The disky ETG fraction decreases with increasing stellar mass both at z~1 and 0, and we do not find significant difference in the fraction between these redshifts in all stellar mass bins. Although uncertainties are large, the results suggest that the isophote shapes and probably dynamical properties of ETGs in massive clusters are characterized at z>1. The constant disky fraction between z~1 and 0 implies that the intermediate mass ETGs in clusters should keep their dynamical properties during the size and morphological evolution in z<1.

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

Copyright (c) 1999-2000 Subaru Telescope, NAOJ. All rights reserved.