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Wide-Field Imaging toward Hubble Deep Field

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Wide-Field Imaging toward Hubble Deep Field Powered By Docstoc
					Deep, wide-field global VLBI
          observations of HDF-N
               Seungyoup Chi
          Kapteyn Institute (RuG) / JIVE


                  Collaborators :
          M. A. Garrett, P. D. Barthel et al.

             8th EVN Symposium 2006
        Torun, Poland, 26-29 September 2006
Contents
 Introduction to HDF

    Previous results (MERLIN and EVN)


 New Global VLBI observations

 VLA J123642+621331 – starburst / AGN ?

 Other detections in HDF-N

 Summary and Future work
Hubble Deep Field North (HDF-N)
•   10 days of HST time

•   Imaged 2.5' × 2.5' of sky

•   Depth (I-band) : ~ 28 mag.

•   High resolution : ~ 40 mas

•   Flanking fields : ~ 25 mag.

•   Follow-up observations
    - Sub-mm, IR, X-ray, Radio,
    Ground-based opt. imaging,
    Spectroscopy…
                                  Richards et al. 1998
Previous results in HDF-N
   MERLIN+VLA 1.4 GHz obs.
   (Muxlow et al. 2005)

- 10-arcmin field
- 92 radio source (S1.4 > 40 μJy)
- noise level ~ 3.3 μJy/beam
Previous results in HDF-N
   EVN 1.6 GHz obs.
   (Garrett et al. 2001)

- 6 (MERLIN) targets
- noise level ~ 30 μJy/beam
  (in dirty maps)
- 3 detections
Global VLBI observation
 Observation : 20 ~ 22 February 2004 (3 × 12 hrs.)
     2 x 8 MHz (RR, LL), 2-bit samples [128 Mbps recording rate]
     EVN disk recording; VLBA on tape.
     16 telescope array including 100-m Greenbank and Effelsberg telescopes, plus 76-m
     Lovell telescope.

 Frequency : 1.4 GHz
       Max. Angular resolution : ~ 4 mas (in HDF-N), increasing taper in HFF.

 Data Correlated at JIVE:
     Correlator running at full throttle…
     Each (1 x 8 MHz) polarisation channel correlated in a separate pass in order to maximise
     spectral resolution (minimise bandwidth smearing)

 Wide-field approach and techniques used to image out entire HDF-N and HFFs
     Total data size : ~ 800 Gbytes (3 epochs, 6 Ifs, 256 sp ch/IF; 0.25 second int. time)
     Images from each IF are co-added together.

 Image Noise level: for a single IF ~ 17 μJy/beam
                    for all 6 Ifs (full data set) reaching ~ 7.3 μJy/ beam in HDF-N
                                                                      (larger in HFF).
VLA J123642+621331
 locate just outside the HDF




                               Richard et al. 1988
VLA J123642+621331
  locate just outside the HDF

  No optical counterpart to
  I ≤ 25 mag.




 a) WFPC2 (I-band)
 b) NICMOS F110W (3-orbits)
 c) NICMOS F160W (6-orbits)
 d) KPNO 4-m
    (Waddington et al. 1999)
VLA J123642+621331
 locate just outside the HDF

 No optical counterpart to
 I ≤ 25 mag.

 Keck spectra : Lyα at z=4.424




                                 Waddington et al. 1999
VLA J123642+621331
 locate just outside the HDF

 No optical counterpart to
 I ≤ 25 mag.

 Keck spectra : Lyα at z=4.424

 Chandra X-ray (0.5 ~ 2.0 keV)




                                 Brandt et al. 2001
VLA J123642+621331
 locate just outside the HDF

 No optical counterpart to
 I ≤ 25 mag.                      VLA/MERLIN
                                  1.4 GHz
 Keck spectra : Lyα at z=4.424
                                  (Muxlow et al.
                                  2005)
 Chandra X-ray (0.5 ~ 2.0 keV)

 radio structure
 : compact comp. + extended emi
 ssion

                                  EVN 1.6 GHz
                                  (Garrett et al.
                                  2001)
VLA J123642+621331
 locate just outside the HDF

 No optical counterpart to
 I ≤ 25 mag.

 Keck spectra : Lyα at z=4.424

 Chandra X-ray (0.5 ~ 2.0 keV)

 radio structure
 : compact comp. + extended emi
 ssion

 radio loud  powered by AGN


                                  Garrett 2001
VLA J123642+621331
Other detections in HDF        (VLA J123644+621133)




               -FR-1 radio galaxy
               -flat spectrum α=0.1
               -elliptical gal. at z = 1.050


                                               Richard et al. 1988
Other detections in HDF      (VLA J123646+621404)




               -inverted spectrum (α = - 0.04)
               -compact + two-sided ext. emission
               -face-on disk gal. at z = 0.961
                                            Richard et al. 1988
VLA 123652+621444   New detection!!!




                              Richard et al. 1988
VLA 123652+621444            New detection!!!
locate just outside of HDF

I = 18.5 mag. elliptical

X-ray counterpart




                                      Brandt et al. 2001
  VLA 123652+621444               New detection!!!
  locate just outside of HDF

  I = 18.5 mag. elliptical

  X-ray counterpart

 inverted spectrum α = - 0.5
 vary in intensity
 AGN at z = 0.321

  compact core + one- sided j
  et-like feature to the east ~
  1.3 arcsec
Summary & Future work
 reach to r.m.s. ~ 7.3 μJy/beam

 4 detections (7 targets in HDF and adjacent HFF) ;
 one new detection

 Analyse the rest of the HFFs (85 radio source targets!)
  provide deep and high-resolution radio source samples

 New data:
    1 Gbps 6cm Global VLBI on VLA J123642+621331
    Target additional deep field region with VLBI
    (probably Spitzer FLSv)
co-add images

       ~ 16 μJy/beam


                       ~ 12 μJy/beam




       ~ 17 μJy/beam

				
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