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تسجيل مستخدم جديدThe evolution of field early-type galaxies to z~0.7
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T. Treu
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We have measured the Fundamental Plane (FP) parameters for a sample of 30 field early-type galaxies (E/S0) in the redshift range 0.1<z<0.66. We find that: i) the FP is defined and tight out to the highest redshift bin; ii) the intercept gamma evolves as dgamma/dz=0.58+0.09-0.13 (for Omega=0.3, Omega_{Lambda}=0.7), or, in terms of average effective mass to light ratio, as dlog(M/L_B)/dz=-0.72+0.11-0.16, i.e. faster than is observed for cluster E/S0 -0.49+-0.05. In addition, we detect [OII] emission >5AA in 22% of an enlarged sample of 42 massive E/S0 in the range 0.1<z<0.73, in contrast with the quiescent population observed in clusters at similar z. We interpret these findings as evidence that a significant fraction of massive field E/S0 experiences secondary episodes of star-formation at z<1.
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