Isophote Shapes of Early-Type Galaxies in Massive Clusters at z ~ 1 and 0 ● Dependance of a4 parameter on mass and size Kazuma Mitsuda(1), Mamoru Doi(1), Tomoki Morokuma(1), Nao Suzuki(1), Naoki Yasuda(1), Saul Perlmutter(2), Greg Aldering(2), Josh Meyers(3) GALAXY EVOLUTION ACROSS TIME, Paris, June 12-16, 2017 ① Introduction ● Size evolution of the ETG samples ● Measuring a4 parameter Refereces ● Evolution of FR fraction: fFR [写真] Dynamics of early-type galaxies (ETGs), whether they are supported by rotation or dispersion, is a clue to understand their assembly history. We compare the isophote shape parameter a4 between z ∼ 1 and 0 as a proxy for dynamics to investigate the epoch at which the dynamical properties are established. We create cluster ETG samples with stellar masses of log(M✽/M⦿) ≥ 10.5 with spectroscopic redshifts. We have 130 ETGs from the Hubble Space Telescope Cluster Supernova Survey for z ∼ 1 and 355 ETGs from the Sloan Digital Sky Survey for z ∼ 0. We ﬁnd similar dependence of the a4 parameter on the mass at z ∼ 1 and 0; the main population changes from disky (a4 > 0) to boxy (a4 ≤ 0) at a critical mass of log(M✽/M⦿) ~ 11.5 with the massive end dominated by boxy ETGs. The disky ETG fraction is consistent between these redshifts. Although uncertainties are large, the results suggest that the isophote shapes and probably dynamical properties of cluster ETGs are already in place at z > 1 and do not signiﬁcantly evolve in z < 1, despite signiﬁcant size evolution. The constant disky fraction imply that the processes responsible for the size evolution is not enough violent to convert the dynamical properties of ETGs. Slow rotators (SRs) Massive: log(M✽/M⦿) > 11.3-5 Tend to be boxy: a4 < 0 Fast rotators (FRs) Less massive: log(M✽/M⦿) < 11.3-5) Tend to be disky: a4 > 0 Dispersion Rotation Slow Rotators Fast Rotators Late-type galaxy Sab Scd Boxy E (a4<0) Disky E (a4>0) S0 (a4>0) Early-type galaxy (ETG) Spin parameter λ SRs FRs Stellar Mass MJAM [M⦿] Eﬀective radius Re[kpc] ● Dynamics and shapes of early-type galaxies (ETGs) ●Illustris Simulation (Penoyre+17) ⇒ Increase of fFR from z ~ 1 to 0 FRs at z~1 SRs at z~0 major mergers etc… z=0 z=1 We investigate evolution of disky (a4 > 0) fraction as a proxy for fFR. ➦ z = 1: HST Cluster Supernova Survey ● z ~ 1 and 0 Cluster ETG Samples z = 0: Sloan Digital Sky Survey z ~ 1 : HST z850 image, z ~ 0 : SDSS g image ② Fit ellipses with Fourier deviation ① Determine isophote contours ③ Get mean a4 value from radial proﬁle Luminosity weighted mean within 2 rPSF < r < 2 rh z=1.2 disky 2 rpsf 2 rh radial proﬁle of a4 z=1.2 boxy 2 rpsf 2 rh radial proﬁle of a4 (Right figures: example of z = 1.2 galaxies) Radial profiles of a4 parameter etc… are derived. 100x a4/a FR SR Disky Boxy log (V / σ) ● Disky ETG fraction (fdisky) at z ~ 0 and 1 Massive end (log(M✽/M⦿)≳11.5) is dominated by boxy ETGs both for z ~ 0 and 1. Disky Boxy For less massive ETGs, smaller galaxies tend to be more disky with larger a4 value both for z ~ 0 and 1. ⬇Averaged a4 value color coded on the size-mass plane ▹ ▹ z ~ 0 sample has galaxies with large sizes (σ ~ 50 - 100 km/s). → recently (z < 1) quenched galaxies? ▹ Disky fraction is consistent between z ~ 0 and 1 within uncertainty taking account of Eddington bias (no significant evolution in z < 1). ▹ z = 0 simulation: fFR z=1 simulation: fFR : z ~ 1 cluster ETGs corrected for Eddington bias Boxy shapes of massive ETGs are already in place at z > 1. ▹ Isophote shapes (boxy/disky) may not reﬂect dynamical states (SR/FR), taking account of the discrepancy between fdisky in observation and fFR in simulation at z = 0. ✻ ⬇Size-mass relation and normalized size distribution of boxy/disky ETGs ✻ normalized size log(re, M11/kpc) = log(re/kpc) - 0.57 ∙ {log(M✽/M⦿)-11} Signiﬁcant size evolution from z ~ 0 to 1 (both in boxy and disky) ⇒ ▹ Cappellari+13 Kormendy & Bender 96 Emsellem+11 K. Mitsuda et al., 2017, ApJ, 834, 109; E. Emsellem et al., 2011, MNRAS, 414, 888; M