The EVLA Vision

1
Microjansky Radio Sources AGN or Star Formation?
Ken Kellermann EdFomalont NRAO
in collaboration with Neal Miller, Paolo
Padovani, Vincenzo Mainieri, Paolo Tozzi
2
Star-formation, AGN, or ?

• History of star and BH formation similar
• Does star formation trigger BH formation?
• Do BHs trigger star formation?
• Is there a common underlying cause?
• Jet feedback? or -
• No single criteria to distinguish AGN SF
• UV/Optical observations
• Morphology, spectra
• Obscuration
• FIR observations
• Good tracer of star formation
• Limited sensitivity/resolution
• X-ray observations
• Good tracer of AGN
• Weak x-ray emission from star formation
• Radio observations
• AGN and SF detectable to large z
• See through gas and dust
• Morphology/Tb (resolution)

Quasars
Shaver et al., 1999
Star formation rate
Hopkins Beacon, 2007
3
VLA data (30 sensitivity level)
Chandra Deep Field South 1 (2) Msec 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 lt 28
Spitzer IRAC/MIPS
GEMS/ACS, VLT/FORS ESO2.2m/WFI
4
CDFS - 20 cm VLA image

• 266 radio sources in CD FS
• s 8.5 µJy
• S gt 43 µJy
• lt 0.5 arcsec position accuracy

89 have X-ray counterparts
5
Optical/X-ray Counterparts in the VLA CDFS

• 254 O/IR counterparts
• 10 Radio galaxies
• AGN SFR
• 107 spectroscopic redshifts
• 79 photo zs (17 bands)
• 12 Sources remain unidentified
• 9 are ambiguous
• 3 no counterpart at any ?
• OIR quiet

6
RID-97
R_WFI
bgt 27.5
vgt 27.5
Rgt 25.5
Kgt 24.4
7
Rlog(Sr/So)
Radio Loud- 63
RL AGN
RQ AGN
8

• Star forming galaxies
• R lt 1.7
• Lrlt 1024.5 W/Hz
• Not E galaxy
• Lx not gt 1042 ergs/sec

Fomalont et al 2008 ApJ S 179, 71
Lx gt 1042 W/Hz R lt 1.4

• Large scatter in µJy count
• Cosmic variance? NO!
• Instrumental errors
• N(S) depends on instrument!
• incompleteness
• primary beam, bandwidth,
• time smearing corrections
• Statistical weight corrections
• Resolution corrections

Padovani et al. ApJ submitted
9
Chandra Deep Field South VLA 20 cm S gt 55 µJy
Kellermann et al. ApJS, v179, 90
Miller et al., unpublished
? 13.3 arcsec
? 3.5 arcsec
10
Resolution vs. confusion

• Resolution lt few asec to avoid confusion at 20 cm
  
• If the nanoJy population has dimensions of 1
  arcsec, natural confusion may be a limiting
  factor

VLAMERLIN Muxlow et al. MNRAS 358, 1159
11
Summary

• Classification as SF or AGN
• Radio and X-ray Luminosity
• Ratio radio/optical flux density
• Optical morphology and spectra reaching faint
  magnitudes
• µJy radio population includes RQ and RL AGN and
  SFG
• SF BH probably co-exist
• There is no correct resolution to use for EVLA
  deep surveys
• Good compromise 1 arcsec (35 km at 2.5 GHz)
• 0.1 arcsec (300 km) to image sub-microJy sources
  (EVLAeMERLIN)
• 0.01 arcsec (3000 km) to distinguish between SF
  and AGN (VLBA EVN)
• AGN Tb gt 105 for 1 µJy
• Issues for the EVLA and for design of the SKA
• Determine the submicroJy source density -
  confusion
• Angular structure natural confusion?
• The importance of cosmic variance
• Optimum frequency for studying faint radio
  sources
• Very high dynamic range ( 105) needed if EVLA is
  to reach the thermal noise limits in a few
  hundred hours
• Primary beam
• Pointing stability

12
CDFS/ECDFS

• 20 6 cm CDFS
• I. Kellermann et al., ApJS , 179, 90 (CDFS VLA)
  
• 8 µ s Jy, ? 3.5 arsec
• II. Mainieri et al. ApJS, 179, 95 (CDFS
  optical)
• III. X-ray sources, Tozzi et al. ApJ, (submitted)
• IV. Population Studies, Padovani et al. ApJ, in
  press
• V. Fomalont et al., 6 cm, s 5 µJy, ? 3.5
  arcsec (in prep)
• VI. CDFS, Miller et al., 20 cm, s 10 µJy, ?
  13 arcsec (in prep)
• 20 cm ECDF
• Miller et al. ApJS, 179, 105
• s 8 µJy, ? 2 arcsec (S gt55 µJy)
• Miller et al. , 20 cm, ? 2 arcsec (in prep)
• s 7 µJy, ? 2 arcsec (S gt 35 µJy)