Friday, 8 August 2008

Size evolution from z=1 to present

figure 7 of van der Wel et al., arXiv:0808.0077

In this paper, the authors find that early-type galaxies grow larger
by a factor of ~2 from z=1 to z=0, consistent with previous studies.
This figure shows the ratio of sizes at the two redshifts from this
work and others, and compares it to the Khochfar & Silk (2006)
semianalytic model. The observed size evolution between z=1-0 is
much steeper than predicted by the model, which is based on the idea
that (cold)-gas-rich mergers at high redshift produce smaller
galaxies than the gas-poor mergers at low redshift.

Probably the most important difference between this and previous
studies is that masses here are calculated using dynamical, rather
than photometric, measurements. Thus, the mass (and hence surface
density) estimates here should be less prone to systematic effects.
Nonetheless, the offset in the size-mass and size-surface density
relations are consistent with the photometric studies. This seems to
imply that any systematic effects are small compared to the observed
size evolution.

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