ﻻ يوجد ملخص باللغة العربية
We present detailed observations of a z~1.99 cluster of submillimeter galaxies (SMGs), discovered as the strongest redshift spike in our entire survey of ~100 SMGs across 800 square arcmin. It is the largest blank-field SMG concentration currently known and has <0.01% chance of being drawn from the underlying selection function for SMGs. We have compared UV observations of galaxies at this redshift, where we find a much less dramatic overdensity, having an 11% chance of being drawn from its selection function. We use this z~1.99 overdensity to compare the biasing of UV- and submm-selected galaxies, and test whether SMGs could reside in less overdense environments, with their apparent clustering signal being dominated by highly active merger periods in modest mass structures. This impressively active formation phase in a low mass cluster is not something seen in simulations, although we propose a toy model using merger bias which could account for the bias seen in the SMGs. While enhanced buildup of stellar mass appears characteristic of other high-z galaxy clusters, neither the UV- nor submm-galaxies in this structure exhibit larger stellar masses than their field galaxy counterparts (although the excess of SMGs in the structure represents a larger volume-averaged stellar mass than the field). Our findings have strong implications for future surveys for high-z galaxies at long wavelengths such as SCUBA2 and Herschel. We suggest that since these surveys will select galaxies during their episodes of peak starbursts, they could probe a much wider range of environments than just the progenitors of rich clusters, revealing more completely the key events and stages in galaxy formation and assembly.
Using the combined capabilities of the large near-infrared Palomar/DEEP-2 survey, and the superb resolution of the ACS HST camera, we explore the size evolution of 831 very massive galaxies (M*>10^{11}h_{70}^{-2}M_sun) since z~2. We split our sample
We use subhalo abundance matching (SHAM) to model the stellar mass function (SMF) and clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) CMASS sample at $zsim0.5$. We introduce a novel method which accounts for the stellar mass incomple
We identify a large sample of isolated bright galaxies and their fainter satellites in the 2dF Galaxy Redshift Survey (2dFGRS). We analyse the dynamics of ensembles of these galaxies selected according to luminosity and morphological type by stacking
We study the evolution of phase-space density during the hierarchical structure formation of LCDM halos. We compute both a spherically-averaged surrogate for phase-space density (Q) and the coarse-grained distribution function f(x,v) for dark matter
Using observations in the COSMOS field, we report an intriguing correlation between the star formation activity of massive (~10^{11.4}msol) central galaxies, their stellar masses, and the large-scale (~10 Mpc) environments of their group-mass (~10^{1