Figure 6.
K-band highresolution images
of the four nearby
(z ~ 0.15) massive
compact galaxies
observed with NIRI
and ALTAIR/LGS.
axies, in particular their inner regions, is the
key ingredient in answering several relevant
questions, such as: What is the morphological
nature of the massive galaxies? Is the compactness only an artifact of missing light in
the outer regions?
To answer these questions, Rodrigo Carrasco
(Gemini Observatory), Trujillo, and Anna Ferré-Mateu (Instituto de Astrofísica de Canarias,
Spain) obtained ultra-deep, high-spatial-resolution images of four nearby super-dense
massive galaxies with the Near-infrared Imager and Spectrometer (NIRI) using the adaptive
optics system Altair (in laser guide star mode)
on the Gemini North telescope.
Contrary to previous studies, where the morphological properties of these galaxies have
been seriously limited by the seeing, the observations provided by Gemini North with
25
GeminiFocus
adaptive optics allowed (for the first time)
an in-depth analysis of their inner and outer
regions to unprecedented resolution. These
galaxies are genuinely very massive and compact, with elongated shapes resembling the
structures of S0 galaxies (Figure 6), with no
evidence of an extended faint component
altering their size estimate. Furthermore, the
stellar mass density profiles are significantly
denser in the inner regions than any galaxy
with similar stellar mass and normal size in the
local universe. Moreover, these galaxies are almost exact copies of the high-redshift (z > 1),
massive compact galaxies. The complete results are presented in The Astrophysical Journal
(Trujillo, I., Carrasco, E. R., and Ferré-Mateu, A.,
751: 45, 2012).
June2012