Found 25 talks width keyword high-redshift galaxies

Thursday March 24, 2011
Prof. Pierre Cox
IRAM, France


In recent years, major changes were done at the IRAM Plateau de Bure interferometer and 30-meter telescope, in particular in the areas of receivers and back-ends. These enhancements increased in significant ways both the sensitivity and the efficiency of both IRAM facilities. I will present results obtained on high-z (2 < 6.4) sub-millimeter galaxies and quasars that illustrate the progress that has been made, emphasizing recent follow-up observations of sources that were uncovered in the Herschel surveys. The talk will end with a presentation of the future projects that are currently under discussion at IRAM, including the NOrthern Extended Millimeter Array (NOEMA), as well as the prospects offered by ALMA.

Monday December 20, 2010
Mr. Fernando Buitrago Alonso
University of Nottingham, UK


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
Mr. Hugo Messias
Centro de Astronomia e Astrofísica da Universidade de Lisboa, Portugal


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.

Tuesday January 26, 2010
Prof. George Miley
Sterrewacht, Univ. Leiden, the Netherlands


Luminous high-redshift radio galaxies (HzRGs) are associated with the most massive known galaxies in the early Universe. These galaxies have the properties expected of the progenitors of dominant galaxies in rich clusters.
I shall describe the properties of HzRGs and demonstrate how they can be used to study the formation and evolution of galaxies and clusters. I shall also show how LOFAR, the new European radio telescope, can be used to extend these probes into the epoch of reionisation.

Friday May 22, 2009
Dr. Christina C. Thöne
Osservatorio Astronomico di Brera (OAB), Italy


Long gamma-ray bursts are supposed to be connected to the death of very massive stars. Due to their brightness, we can detect them to much larger distances than supernovae. Using them as powerful lightsources, they allow us to study star-forming high redshift galaxies and their interstellar medium in great detail with medium and high resolution spectroscopy. Despite the large redshift ranged spanned by GRBs, there is surprisingly little evolution in the properties of their host galaxies which might indicate that GRBs can only occur under certain conditions. This can be investigated from a few bursts at very low redshifts where we can resolve their host galaxies e.g. with integral field spectroscopy. The immediate surroundings might allow us some conclusions on the progenitors of GRBs.

<< First 1 | 2 | 3 Older »

Upcoming talks

  • TODAY: Sistema de control de EST
    Jorge Quintero Nehrkorn
    Friday October 7, 2022 - 10:00 GMT+1  (Aula)
  • TBD
    Dr. Roger Hoyland
    Friday October 14, 2022 - 10:00 GMT+1  (Aula)

More upcoming talks

Recent Colloquia

Recent Talks