The Jy Radio Source Population: the VLACDFS View - PowerPoint PPT Presentation

Title: The Jy Radio Source Population: the VLACDFS View


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The ?Jy Radio Source Population the VLA-CDFS
View
Paolo Padovani (ESO) V. Mainieri (ESO), P.
Tozzi (INAF), K. Kellermann, E. Fomalont
(NRAO), N. Miller (JHU/NRAO), P.
Rosati, P. Shaver (ESO)

• The VLA Survey of the Chandra Deep Field South
• Available data
• Source Population
• Main result star-forming galaxies make up only
  1/3 of the sub-mJy radio sources (contrary to
  the prevailing view)

in the audience
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VLA Observations
1.4 GHz (20 cm)
20 6 cm (50 32 h) ? 3.5 s20 8 µJy 267
radio sources Complete sample 198 sources
reaching S20 43 µJy (5s)
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VLA data (30 sensitivity level)
Chandra Deep Field South 942 ks exposure 366
X-ray sources 5 x 10-17 ergs/sec
16 arcmin
Extended CDFS 250 ks per field
Hubble UDF 976 ks exposure B, V, I, z 10,000
galaxies mag 29
GOODS ACS B, V, i, z I lt 28
GEMS/ACS, VLT/FORS ESO2.2m/WFI
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VLA-CDFS main ancillary data

• Reliable optical/near-IR IDs for 96 of the radio
  sources
• Optical morphological classification for
  54 of the sample. Of these 38 SpInt, 30 EL,
  16 compact, 15 IrrComplex
• Redshift information for 70 (186) of the
  objects 85 spectroscopic (32), 101 photometric
  (38) ltzgt 0.8 0.03 - 3.7
• Some (14) optical spectral classification
• X-ray detections for 32 (85) of the objects,
  upper limits for all the others

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Number Counts
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Optical radio fluxes
R log(S1.4GHz/SV)
40 of the sources have R NOT typical of
star-forming galaxies (too large)
WARNING a sample with a brighter mag. cut would
get a very different result 10!
Star-forming galaxies
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Optical radio power
Sources with no morphological info have largest R
and N(Pr) different from that of SpInt and
similar to that of EL
Sources with no redshift info have also
relatively large R and estimated Pr
Estimated star-forming fraction lt 45
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X-ray radio powers
Sources with no morphological info have
relatively large Lx and N(Lx) different from that
of SpInt and similar to that of EL
Estimated star-forming fraction 30
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Star-forming galaxies fraction

20 lt SF fraction lt 45 trend increasing at
lower fluxes
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Summary

• We have studied 267 radio sources from our deep
  (8.5 mJy r.m.s.) Chandra Deep Field South 1.4 and
  5 GHz VLA survey.
• We have used a wealth of multi-wavelength
  information in the radio, optical, and X-ray
  bands, including optical morphology and our
  unique (70) redshift information.
• All the available evidence points to star-forming
  galaxies constituting only a minority ( 30) of
  the sub-mJy sources, at variance with some
  previous results. Most of our sources are still
  radio galaxies.
• Stay tuned for more Kellermann et al.,
  Mainieri et al., Tozzi et al., Padovani et al.,
  soon to be submitted (and more to come)