Marco P. Viero, Lorenzo Moncelsi, Erin Mentuch, Fernando Buitrago, Amanda. E. Bauer, Edward L. Chapin, Christopher J. Conselice, Mark J. Devlin, Mark Halpern, Gaelen Marsden, Calvin B. Netterfield, Enzo Pascale, Pablo. G. Pérez-González, Marie Rex, Douglas Scott, Matthew W. L. Smith, Matthew D. P. Truch, Ignacio Trujillo, Donald V. Wiebe
We present measurements of the mean mid-infrared-to-submillimeter flux
densities of massive (M\ast \approx 2 \times 10^11 Msun) galaxies at redshifts
1.7 < z < 2.9, obtained by stacking positions of known objects taken from the
GOODS NICMOS Survey (GNS) catalog on maps: at 24 {\mu}m (Spitzer/MIPS); 70,
100, and 160{\mu}m (Herschel/PACS); 250, 350, 500{\mu}m (BLAST); and 870{\mu}m
(LABOCA). A modified blackbody spectrum fit to the stacked flux densities
indicates a median [interquartile] star-formation rate of SFR = 63 [48, 81]
Msun yr^-1 . We note that not properly accounting for correlations between
bands when fitting stacked data can significantly bias the result. The galaxies
are divided into two groups, disk-like and spheroid-like, according to their
Sersic indices, n. We find evidence that most of the star formation is
occurring in n \leq 2 (disk-like) galaxies, with median [interquartile] SFR =
122 [100,150] Msun yr^-1, while there are indications that the n > 2
(spheroid-like) population may be forming stars at a median [interquartile] SFR
= 14 [9,20] Msun yr^-1, if at all. Finally, we show that star formation is a
plausible mechanism for size evolution in this population as a whole, but find
only marginal evidence that it is what drives the expansion of the
spheroid-like galaxies.
View original:
http://arxiv.org/abs/1008.4359
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