RADIO-LOUD

1
RADIO-LOUD ACTIVE GALACTIC NUCLEI Rafal
Moderski Nicolaus Copernicus Astronomical Center,
Warsaw
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Outline.
1. Introduction. 2. Multiwavelength
observations of jets. 3. Polarization
measurements and magnetic field. 4. Jet
content. 5. Host galaxies. 6. High redshift
quasars. 7. Summary. Note very high energy
will be discussed in future talks.
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Introduction radio loudness.
- simple radio power (Baum Heckman 1989
Miller, Peakock Mead 1990 Miller, Rawlings
Saunders 1993), or the radio-loudness parameter
(Kellermann et al. 1989) - radio dichotomy
of quasars (Strittmatter et al. 1980) radio-loud
quasars (RLQs) with Rgt10 (0.1-3) and radio-quiet
quasars (RQQs) with Rlt10 (100-1000) as radio
power is concerned the division is Lr 1025 W
Hz-1 - 81 of quasars are RL (3225 SDSS/FIRST
Ivezic et al. 2002) - ongoing debate (White et
al. 2000 Ivezic et al. 2002 Cirasuolo et al.
2003 Ivezic et al. 2004) Celotti's talk
Miller, Rawlings Saunders 1993 Rawlings 1994
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Introduction jets.
- RL and RQ similar at infrared, optical and
ultraviolet wavelengths (Steidel Sargent 1991
Sanders et al. 1989 Francis, Hooper Impey
1993 Zheng et al. 1997) - unique feature of RL
large scale jets (Moffet et al. 1971)
although small scale jets also present in RQ
(Falcke 2001)
Sanders et al. 1989
Willis et al. 1982 Perley Bridle 1984 Perley,
Bridle Willis 1984 Cohen Readhead 1979
Bridle Perley 1984
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Introduction jets.
M87 from 200 000 to 0.2 ly
Owen (NRAO), Biretta (STScI) et al.
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Jets radio observations.
- highly collimated, lt few degrees, (unresolved
transverse structure) flow often showing apparent
supeluminal motion (Cohen et al. 1977) -
apparent velocities 0-15c reaching gt30c, but this
appears to be frequency dependent (shorter
wavelengths-faster speeds) transverse
structure - many features move with similar
velocities, but stationary and inward moving
features are also present in some sources -
patterns - change of direction of motion -
gamma-ray sources tend to have higher Doppler
factors - variability studies does not found
significant differences between RL and RQ
(Barvainis et al. 2005) (Kellermenn et al. 1998,
1999, 2003 Zensus et al. 2002 Vermeuelen et al.
2003 Jorstad et al. 2001 Britzen et al. 2001
Homan et al. 2001)
Vermeulen et al. 2003
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Jets optical observations.
- HST mostly used to study host galaxies (e.g.
O'Dowd Urry 2005) - core optical emission
correlates with radio (Chiaberge et al. 1999,
2002 Verdoes Kleijn et al. 2002) indicating
common origin (synchrotron emission from the jet
base) - optical observations probe faster cooled
electrons
M87, HST
3C 270, Chiaberge et al. 2003
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Jets X-ray observations.
- RL sources are X-ray brighter for given optical
luminosity two components (Zamorani et al.
1981) - correlation X-ray core radio emission
for radio galaxies (Fabbiano et al. 1984) - only
3 detections M87, Cen A and 3C 273 Chandra
era - many jets resolved two-sided (3C 270
Zezas et al. 2004) and compact (PKS 0521
Birkinshaw et al. 2002) - jets shorter in X-rays
than in radio - knotty structure shocks from
deceleration by environment (Hardcastle et al.
2002) - in low power radio sources X-rays from
synchrotron emission of high energy electrons
in situ acceleration (Warrall astro-ph/0412532)
Marshall et al. 2005 Schwartz et al. 2005
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Jets X-ray observations.
- high-power radio sources also detected in
X-rays (Chartas et al. 2000 Sambruna et al.
2002 Marshall et al. 2004) - spectral energy
distribution often shows other than synchrotron
mechanism (Sambruna et al. 2002) - different
electron populations due to transverse velocity
structure (Jorstad Marscher 2004) or the
Klein-Nishina effects (Dermer Atoyan 2002) -
inverse Compton scattering of cosmic microwave
background (Tavecchio et al. 2000 Celotti et al.
2001) radio produced by electrons with Lorentz
factor 104-5 while X-rays 102-3 - detectable to
arbitrary redshift (Schwartz 2002) - bulk
comptonization (PKS 0637-752 Georganopoulos et
al. 2005) problems - fast jet speed up to
hundreds of kpc - decreasing X-ray emission
along the jet (Sambruna et al. 2004 Marshall et
al. 2001) - radio-X-ray offsets (Siemiginowska
et al. 2002)
Sambruna et al. 2002
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Jets X-ray observations.
Siemiginowska et al. 2002
- PKS 1127-145 at z1.187 - offsets as possible
indicators of acceleration in the wake of the
shock (Hardcastle et al. 2003)
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Jets multiwavelength.
1.647GHz Merlin
HST
Chandra
- X-rays fade along the jet, optical knots have
similar morphology, while radio brightens -
single synchrotron model with index 0.76 fits the
spectrum from 1.6GHz to 5keV indicating electrons
with energies gt107 - luminosity 1.5x1043
erg/s - knots may indicate helical structure
3C 273 Marshall et al. 2001
higher energies - Hudec's talk Benbow's talk
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Polarization.
- linear polarization detected from both kpc and
pc scale jets (Perley et al. 1984 Fomalont et
al. 1980 Cawthorne Gabuzda 1996) -
theoretically as high as 70, typically 1-10
(Jones et al. 1985 Rudnick et al. 1986), but may
reach 40 and higher in some sources (Homan
Wardle 1999) - indicates inhomogeneous magnetic
field with some small degree of ordering shock
compression (Hughes et al. 1989), shear ordering
(Begelman et al. 1984) - usually longitudal at
the beginning and perpendicular at larger
distances - complicated if knots are present in
the jet evidence for shocks
Perley et al. 1984
Cawthorne Gabuzda 1996
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Polarization.
Perlman et al. 1999
- transverse magnetic field at shock regions -
evidence for transverse structure of acceleration
region - evidence for spine moving faster than
outer layers of the jet bulk motion different
from radio maps and radiation models - HST
polarimetry especially useful (short lifetime of
electrons, no Faraday depolarization) (Perlman et
al. 2005)
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Polarization.
- circular polarization detected only in pc scale
jets (gt20 AGNs) (Homan Wardle 1999, 2004 Homan
et al. 2001 Rayner et al. 2000) - small
0.1-0.5 (3 in 3C 84 Homan Wardle 2004), but
may be measured with accuracy 0.01 with ATCA
(Rayner et al. 2000) - maybe of intrinsic origin
(Legg Westfold 1968), but requires strong,
highly ordered magnetic field (Homan Wardle
2004) - other mechanisms scintillation
(Macquart Melrose 2000), general relativistic
effects in dispersive plasma (Broderick
Blandford 2002) or Faraday conversion (Jones
O'Dell 1977 Ruszkowski Begelman
2002) (Ruszkowski astro-ph/0210102)
3C 273 Homan Wardle 1999
3C 84 Homan Wardle 2004
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Jet composition.
- jets must contain fast charged particles and
magnetic field - early studies (Wardle et al.
1998) favored electron-positron plasma with low
minimum energies - various possibilities
electron-positron plasma, electron-proton plasma,
Poynting flux dominated (Rees 1971) or proton
dominated (Mannheim Biermann 1989 Protheroe et
al. 2003) Pohl's talk - acceleration of jet
bulk motion may be a sign of conversion of
magnetic energy to kinetic energy (Homan et al.
2001), but seems to be frequency dependent also
spots may indicate patterns not motion -
internal shocks (Sikora et al. 1994 Spada et al.
2001) vs. magnetic recconection - possible
change of primary energy carriers along the
jetelectro-magnetic at the base (Lovelace et
al. 2002) than particle loaded (Sikora Madejski
2000 Sikora et al. 2005) - protons sometimes
required to power radio-lobes (Tavecchio et al.
2000 Sikora Madejski 2000) but sometimes not
(Croston et al. 2003 Hardcastle et al. 2004) -
urgent need for theory of electron shock
acceleration in the environment dynamically
dominated by protons - although expected
(Celotti et al. 1998) no evidence of thermal
matter yet, but blue-shifted iron line may be
detected by future missions like NeXT or XEUS in
3C 273 (Wang et al. 2004)
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Dunlop et al. 2003
Host galaxies.
- simple historical dichotomy (Smith et al. 1986
Hutchings et al. 1989) does not hold any more -
extensive HST studies (Dunlop et al. 2003 Hooper
et al. 1997 Boyce et al. 1998) - almost all
(both RL and RQ) quasars live in elliptical
galaxies some low luminosity RQs hosts have disc
components - RQ hosts are less luminous than RL
and radio galaxies (support for unification) -
many similarities with inactive elliptical
galaxies random selection - host galaxy
morphology, black hole mass or black hole fueling
rate are not primary factors of radio loudness
spin of the black hole (Blandford 2000 Wilson
Colbert 1995) - RL are never found in spiral
galaxies
radio-loud PKS 1020-103
radio-quiet 0204292
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Host galaxies.
- RL are never found in spiral galaxies -
exception 0313-192 - 200kpc FRI source at
z0.067 seen almos edge on (inclination
0.5deg) - evidence for recent minor merger -
supports further the idea that other properties
than host galaxy type are responsible for jet
activity
Keel et al. 2002
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High-z quasars.
- quasars vs. normal galaxies - over 900 zgt4
quasars known (zgt5 50 zgt6 8) (Fan 2004) -
emission lines and continuum properties (optical,
X-ray) of high-z quasars exhibit no significant
evolution as compared to low redshift (Fan et al.
2004 Vignali et al. 2003 Bassett et al. 2004) -
no sign of lensing despite estimations that 30
(0-100)should be lensed (Wyithe Loeb 2002
Comerford et al. 2002) - high BH masses
(109-10Msol) and solar metallicity put severe
constraints on galaxy formation scenarios (1Gyr)
(Haiman Loeb 2001) - only 1 RL at z5.77, but
no evidence for extended emission
VLA Frey et al. 2005
SDSS Fan et al. 2001
Chandra Brandt et al. 2002
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High-z quasars.
- for a long time there was no extended X-ray
emission from zgt4 RL quasars problem for IC/CMB
model (Bassett et al. 2004) - also
1745624 at z3.889 and PMN J2219-2719 at z3.634
(Cheung et al. 2005)
Cheung 2004
Siemiginowska et al. 2003
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High-z quasars.
Schwartz et al. 2004
- for even higher redshifts the only suspect is
SDSS 1306 at z5.99, but - no radio detection
(1mJy upper limit both on core and jet - 23rd
magnitude galaxy found at the position of the jet
feature (Ivanov 2002) - deep Chandra observation
under way - possible radio-quiet X-ray jets
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Summary.
- multiwavelength studies with previously unseen
accuracy allow better understanding of jet
kinematics, its structure, radiation mechanisms
and environments - unified picture of
relativistic outflows quasars, microquasars
Chaty's talk and gamma-ray bursts (Mirabel
2003 Ghisellini 2003) De Rujula's talk or
pulsars Kazanas's talk - polarization
measurements important for studies of magnetic
field strength and structure, the energy spectrum
of radiating particles and jet composition,
although current results inconclusive - host
galaxies study suggests that central engin
properties rather than galaxy morphology are
responsible for jet activity - high-z quasars
observations put constraints on galaxy formation
and evolution theories, probe reionization epoch
and also test primary radiation mechanisms of kpc
jets - the future is bright (ATCA, Spitzer -
e.g. should detect bulk Compton in PKS 0637,
Integral/Chandra/XMM, GLAST, HESS)
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Phenomena in the Universe, La Thuile, Italy