* Astronomy

Title: The GOODS NICMOS Survey: First Results
Authors: Conselice, Christopher; GNS Team

We present the first results from the GOODS NICMOS Survey (GNS), a 180 orbit Hubble Space Telescope program to image with NICMOS in the F160W (H-band) a sample of 60 massive, M* > 1011 M0, galaxies at z > 2 found in both the GOODS-North and GOODS-South fields. While the primary goal of the survey is to examine the structures and sizes of these massive galaxies, our data also contain dozens of V- and i-drop galaxies, as well as sub-mm detected galaxies, and evolved massive galaxies at z > 4. We present the first results from this survey, including measures of structures and sizes of massive galaxies at z > 2, giving the first detailed rest-frame optical view of galaxies at this epoch.

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Title: Size Evolution of the Most Massive Galaxies at 1.7 < z < 3 from GOODS NICMOS Survey Imaging
Authors: Fernando Buitrago, Ignacio Trujillo, Christopher J. Conselice, Rychard J. Bouwens, Mark Dickinson and Haojing Yan

We measure the sizes of 82 massive (M >= 10^11 Msun) galaxies at 1.7 <= z <= 3 utilising deep HST NICMOS data taken in the GOODS North and South fields. Our sample is almost an order of magnitude larger than previous studies at these redshifts, providing the first statistical study of massive galaxy sizes at z > 2, confirming the extreme compactness of these systems. We split our sample into disk-like (n <= 2) and spheroid-like (n > 2) galaxies based on their Sérsic indices, and find that at a given stellar mass disk-like galaxies at z ~ 2.3 are a factor of 2.6 ± 0.3 smaller than present-day equal-mass systems, and spheroid-like galaxies at the same redshifts are 4.3 ± 0.7 smaller than comparatively massive elliptical galaxies today. At z > 2 our results are compatible with both a levelling off, or a mild evolution in size. Furthermore, the high density (~2 x 10^10 Msun kpc^-3) of massive galaxies at these redshifts, which are similar to present-day globular clusters, possibly makes any further evolution in sizes beyond z = 3 unlikely.

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