problem of weak radio emission

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problem of weak radio emission
FR II or FR I ?
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The origin of weak radio emission in Type-2
radio-quit quasars
- the new era of mJy VLBI observations -

• Hans-Rainer Klöckner
• Alejo Martínez-Sansigre
• Mike Garrett
• Steve Rawlings
• Paul Alexander
• David Green
• Julia Riley

8th European VLBI Network Symposium, Torun, Poland
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Intro - the sample
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
Spitzer FLS VLA-B
Condon et al. AJ 2003
700 deg-2
S3.6 mm 45 mJy ? z gt 2 ?1.2 ?m exclude
type I
S24 mm gt 300 mJy ? z gt 2 L 0.2 L Quasar
break luminosity
2 mJy S1.4GHz 350 mJy ? Exclude ULIRG FRII
Martínez-Sansigre et al. Nature 2005

• population of 21 distant type II quasars in 3.8
  sq.degrees

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Intro - sub-sample

• population of 11 distant type II quasars
• in 3.8 deg2 redshift range 2 - 4.169

Z gt 2
redshifts 7 spec 3 photo AMS01,
AMS09,AMS21, 1 not obs AMS15
Optical mR 23.8 - 25.3 ? L1.4GHz FRI FRII _at_
2.5E24 W / (Hz sr)
Ledlow Owen 1996
composite spectrum
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the idea
HDF J123642 621331 z 4.424
WSRT 489 mJy ? VLA-A 467 mJy ?
MERLIN 472 mJy ? EVN 248 mJy
EVN 1.4 GHz rms 40mJy Garrett et al. 2001
MERLIN 1.4 GHz Muxlow et al. 2005
dusty , starforming galaxy embedded AGN
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EVN observations
3 x 12 hrs in October November 2005 EF, (WB),
JB, ON, MC, NT, TR, UR, SH
J17225856
Correlated December / January 2005/2006
Bob, Lisa, Rebeca
8 IF 32 channels 0.5 MHz per channel ? 128 MHz
band !!!
MK5 recording system 9 x 3275 Gbytes !!!
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EVN observing strategy
8 IF, 4-28 channels ?200 channels ? 123.5 MHz
J17225856
centre frequency 1658.24 MHz
o
separation 2 deg flux recovered
J17226105
W171156
131 mJy
15.5?2 mJy
o
VLBA 17.03?1.3 mJy
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results
rms 26 ?Jy 6-7? rms peak ? 8 out of 11 72
AMS01, AMS06, AMS17
AMS03
AMS19
AMS09
AMS05
AMS15
AMS12
AMS16
AMS21
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VLBI surveys
NOAO Bootes Field 0.28 deg2 3 out of 24 6
out of 37
? detection rate sub-mJy is 84-5 and 2911-12
mJy
Garrett et al. ApJ 2004
HDF HFF 0.5 deg2 2 out of 92 2 for rms
33mJy
Garrett et al. AA 2000
HDF 0.5 deg2 4 out of 7 57 for rms 7mJy
Seungyoup Chi 2006
Spitzer FLS 12 out of 20 lt 1deg, 60 with gt2
mJy rms 333mJy
Wrobel et al. ApJ 2004
FIRST 1.1mJy 71 14 out of 256 sources 28-33

Porcas et al. 2004
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results
expected / observed
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4.9 GHz flux / observed
fraction / spec index
1.5
for Z gt 2 15 GHz versus 5 GHz source rest frame
SBN
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putting it together
optical
type
radio
I
FRI / II
X
II
Martínez-Sansigre et al. sub 2006
8 out of 11 Sources with EVN detection rate 73
radio infrared selection helps
recover around 50 of flux within the inner 300
pc
AGN feedback could switch off star formation
would expect 4.3 type I quasars 3.8 deg2
8 - 11 type II 13 hard X-ray or 11
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the future
10 -15 years from ?Jy to nJy
Jarvis et al. In prep.
SKADS
1deg2