Bibcode
Carrasco, Eleazar R.; Conselice, Christopher J.; Trujillo, I.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 405, Issue 4, pp. 2253-2259.
Advertised on:
7
2010
Número de citas
56
Número de citas referidas
51
Descripción
We present deep K-band adaptive-optics observations of eight very
massive (M* ~ 4 × 1011Msolar)
galaxies at 1 < z < 2 utilizing the Gemini NIRI/Altair Laser Guide
System. These systems are selected from the Palomar Observatory
Wide-Field Infrared survey, and are amongst the most massive field
galaxies at these epochs. The depth and high spatial resolution of our
images allow us to explore for the first time the stellar mass surface
density distribution of massive distant galaxies from 1 to 15 kpc on an
individual galaxy basis, rather than on stacked images. We confirm that
some of these massive objects are extremely compact with measured
effective radii between 0.1 and 0.2arcsec, giving sizes which are <~2
kpc, a factor of ~7 smaller in effective radii than similar mass
galaxies today. Examining stellar mass surface densities as a function
of fixed physical aperture, we find an overdensity of material within
the inner profiles, and an underdensity in the outer profile, within
these high-z galaxies compared with similar mass galaxies in the local
universe. Consequently, massive galaxies should evolve in a way to
decrease the stellar mass density in their inner region and at the same
time creating more extensive outer light envelopes. We furthermore show
that ~38 +/- 20 per cent of our sample contains evidence for a disturbed
outer stellar matter distribution, suggesting that these galaxies are
undergoing a recent dynamical episode, such as a merger or accretion
event. We calculate that massive galaxies at z < 2 will undergo on
the order of 5 of these events, a much higher rate than observed for
major mergers, suggesting that these galaxies are growing in size and
stellar mass in part through minor mergers during this epoch.
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