Found 2 talks width keyword GOODS
Monday December 20, 2010
University of Nottingham, UK
Abstract
Massive (≥ 1011 M⊙) galaxies at high redshift (z ≥ 1.5) remain mysterious objects. Their extremely small sizes (effective radii of 1-2 kpc) make them as dense as modern globular clusters. It is thought that a highly dissipational merger is needed to create such compact type of galaxies. We will discuss this issue, along with state-of-the-art morphological and kinematic observations of these objects. In the present day Universe massive galaxies show large sizes, and harbor old and metal-rich stellar populations. In order to explore their development, we present near-IR IFU observations with SINFONI@VLT for ten massive galaxies at z=1.4 solely selected by their high stellar mass which allow us to retrieve velocity dispersions, kinematic maps and dynamical masses. We joined this with data and works coming from the GOODS NICMOS Survey, the largest sample of massive galaxies (80 objects) with high-resolution imaging at high redshift (1.7 < z < 3) acquired to date. As a result, we show how their morphology changes possibly through elusive minor merging.
Friday October 29, 2010
Centro de Astronomia e Astrofísica da Universidade de Lisboa, Portugal
Abstract
In this talk, I will cover our contribution to the study of extremely red galaxy (ERG) populations presenting a multi-wavelength analysis of these objects, selected in the GOODS-South/Chandra Deep Field South field. By using all the photometric (from X-rays to radio) and spectroscopic information available on large deep samples of extremely red objects (EROs, 645 sources), infrared EROs (IEROs, 294 sources) and distant red galaxies (DRGs, 350 sources), we derive redshift distributions, identify AGN powered and star-formation powered galaxies (based on X-ray properties and a new IR AGN diagnostic developed by us), and, using the radio observations of this field, estimate robust (AGN- and dust-unbiased) star formation rate densities (SFRD) for these populations. Applying a redshift separation (1 ≤ z < 2 and 2 ≤ z ≤ 3) we find a significant rise (a factor of 1.5 — 3) of SFRD for EROs and DRGs toward high-z, while none is observed for IEROs. As expected, we find a significant overlap between the ERG populations, and investigate the properties of "pure" (galaxies that conform to only one of the three considered ERG criteria) and "combined" (galaxies conforming to all three criteria) sub-populations. We find ERG sub-populations with no AGN activity and intense star-formation rates. With average values of ~180 M⊙/yr at 2 ≤ z < 3, they reasonably contribute to the global star-formation rate density, reaching a > 20% level. Strong AGN behaviour is not observed in the ERG population, with AGN only increasing the average radio luminosity of ERGs by 10 — 20%. However, AGN are frequently found (in up to 27% of the ERG population), and would increase the SFRD estimate by over 100%. Thus, and while the contribution of SF processes to the radio luminosity in galaxies with AGN remains uncertain, a comprehensive identification of AGN in these populations is necessary to obtain meaningful results. The dust content to each population is also derived by correlating UV and Radio SFRs, giving a higher obscuration for more active SF sources. Also, know to be amongst the most massive galaxies in the high-z universe, I will show that ERGs may constitute up to 60% of the total mass in the universe at 1 ≤ z ≤ 3. Finally, preliminary and promising results are presented on the morphologies of ERGs (CAS and Gini/M20 parameters) based on the v1.9 ACS GOODS-S images.« Newer Older »
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