1. problem of weak radio emission FR II or FR I ?

2. Hans-Rainer Klöckner Alejo Martínez-Sansigre Mike Garrett Steve Rawlings Paul Alexander David Green Julia Riley The origin of weak radio emission in Type-2 radio-quit quasars - the new era of  Jy VLBI observations - 8th European VLBI Network Symposium, Torun, Poland

3. Intro - the sample S 24  m > 300  Jy  z > 2: L ≥ 0.2 L * Quasar break luminosity  population of 21 distant type II quasars in 3.8 sq.degrees [Martínez-Sansigre et al. Nature 2005] S 3.6  m ≤ 45  Jy  z > 2: ~1.2  m exclude type I Condon et al. AJ 2003 Spitzer FLS VLA-B 2 mJy ≥ S 1.4GHz ≥ 350  Jy  Exclude ULIRG & FRII type I good understanding optical LF z ~ 2 population of obscured radio quit quasars postulated from hard X-ray background  give hint of black-hole growth ~# 700 deg -2

4. Normalized 100%; < 2000 kms -1 36%9% 4% Martínez-Sansigre et al. MNRAS 2006 composite spectrum Intro - sub-sample  population of 11 distant type II quasars in 3.8 deg 2 redshift range 2 - 4.169 Z > 2: redshifts: 7 spec & 3 photo [AMS01, AMS09,AMS21], 1 not obs [AMS15] Optical m R = 23.8 - 25.3  L 1.4GHz FRI FRII @ 2.5E24 W / (Hz sr) [Ledlow & Owen 1996]

5. MERLIN 1.4 GHz [Muxlow et al. 2005] EVN 1.4 GHz [rms 40  Jy; Garrett et al. 2001] WSRT 489  Jy  VLA-A 467  Jy  MERLIN 472  Jy  EVN 248  Jy HDF: J123642 + 621331 z = 4.424 the idea dusty, starforming galaxy + embedded AGN

6. 3 x 12 hrs in October & November 2005 EF, (WB), JB, ON, MC, NT, TR, UR, SH Correlated: December / January 2005/2006 MK5 recording system 9 x 3275 Gbytes !!! EVN observations 8 IF 32 channels 0.5 MHz per channel  128 MHz band !!! J1722+5856 Bob, Lisa, Rebeca

7. EVN observing strategy 8 IF, 4-28 channels  200 channels  123.5 MHz centre frequency 1658.24 MHz J1722+5856 J1722+6105 W171156 separation ~2 deg flux recovered [131 mJy] [15.5  2 mJy ] o o [VLBA 17.03  1.3 mJy ]

8. results AMS03 AMS12 AMS16 AMS15 AMS21 AMS19 AMS09AMS05 rms ~ 26  Jy; 6-7  rms peak  8 out of 11 72% [AMS01, AMS06, AMS17]

9. VLBI surveys NOAO Bootes Field: 0.28 deg 2 3 out of 24 & 6 out of 37  detection rate sub-mJy is 8 +4 -5 % and 29 +11 -12 % mJy Garrett et al. ApJ 2004 HDF + HFF : ~0.5 deg 2 2 out of 92 [2%] for [rms ~33  Jy] Garrett et al. A&A 2000 FIRST : 1.1mJy 71 + 14 out of 256 sources 28-33 % Porcas et al. 2004 Wrobel et al. ApJ 2004 Spitzer FLS : 12 out of 20 [ 2 mJy [rms ~333  Jy] Seungyoup Chi 2006 HDF : ~0.5 deg 2 4 out of 7 [57%] for [rms ~7  Jy]

10. results 1.5 2 expected / observed 4.9 GHz flux / observed fraction / spec index for Z > 2 ~15 GHz versus ~5 GHz source rest frame SBN

11. would expect 4.3 type I quasars 3.8 deg 2 8 out of 11 Sources with EVN detection rate 73 % recover around 50% of flux within the inner 300 pc AGN feedback could switch off star formation putting it together radio & infrared selection helps 8 - 11 type II 1:3 [hard X-ray] or 1:1 [Martínez-Sansigre et al. sub 2006] 3 5 9 12 15 19 21 X 16 optical type I II FRI / II X radio

12. Jarvis et al. In prep. 10 -15 years from  Jy to nJy the future 1deg 2 SKADS