1. Deep, wide-field global VLBI observations of HDF-N 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

2. 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

3. 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

4. Previous results in HDF-N MERLIN+VLA 1.4 GHz obs. (Muxlow et al. 2005) - 10-arcmin field - 92 radio source (S 1.4 > 40 μJy) - noise level ~ 3.3 μJy/beam

5. 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

6. 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).

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

8. 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)

9. 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

10. 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

11. VLA J123642+621331 VLA/MERLIN 1.4 GHz (Muxlow et al. 2005) EVN 1.6 GHz (Garrett et al. 2001) 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

12. 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

13. VLA J123642+621331

14. Richard et al. 1988 Other detections in HDF (VLA J123644+621133) -FR-1 radio galaxy -flat spectrum α=0.1 -elliptical gal. at z = 1.050

15. Other detections in HDF (VLA J123646+621404) Richard et al. 1988 -inverted spectrum (α = - 0.04) -compact + two-sided ext. emission -face-on disk gal. at z = 0.961

16. VLA 123652+621444 New detection!!! Richard et al. 1988

17. VLA 123652+621444 New detection!!! locate just outside of HDF I = 18.5 mag. elliptical X-ray counterpart Brandt et al. 2001

18. 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

19. 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)

20. co-add images ~ 16 μJy/beam ~ 17 μJy/beam ~ 12 μJy/beam