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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20101029T000000
DTEND;TZID=Atlantic/Canary:20101029T010000
UID:iactalks-223
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/223
CREATED:2010-10-29T00:00:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:A multi-wavelength approach to the properties of Extremely Red Gala
 xy populations: star formation rate and mass densities, AGN and dust conte
 nt, and morphology
DESCRIPTION:A multi-wavelength approach to the properties of Extremely Red 
 Galaxy populations: star formation rate and mass densities, AGN and dust c
 ontent, and morphology\nMr. Hugo Messias\n\nIn this talk, I will cover our
  contribution to the study of extremely red galaxy (ERG) populations prese
 nting 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 samp
 les of extremely red objects (EROs, 645 sources), infrared EROs (IEROs, 29
 4 sources) and distant red galaxies (DRGs, 350 sources), we derive redshif
 t distributions, identify AGN powered and star-formation powered galaxies 
 (based on X-ray properties and a new IR AGN diagnostic developed by us), a
 nd, 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 f
 ind a significant rise (a factor of 1.5 — 3) of SFRD for EROs and DR
 Gs toward high-z, while none is observed for IEROs. As expected, we find a
  significant overlap between the ERG populations, and investigate the prop
 erties of "pure" (galaxies that conform to only one of the three considere
 d ERG criteria) and "combined" (galaxies conforming to all three criteria)
  sub-populations. We find ERG sub-populations with no AGN activity and int
 ense star-formation rates. With average values of ~180 M⊙/yr at 2 &l
 e; z < 3, they reasonably contribute to the global star-formation rate 
 density, reaching a > 20% level. Strong AGN behaviour is not observed in t
 he ERG population, with AGN only increasing the average radio luminosity o
 f 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 du
 st content to each population is also derived by correlating UV and Radio 
 SFRs, giving a higher obscuration for more active SF sources. Also, know t
 o 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 o
 n the morphologies of ERGs (CAS and Gini/M20 parameters) based on the v1.9
  ACS GOODS-S images.
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