Download radio loudness. - Rencontres de Moriond

RADIO-LOUD
ACTIVE GALACTIC NUCLEI
Rafal Moderski
Nicolaus Copernicus Astronomical Center, Warsaw
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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)
R
f 5GHz
f OIII
- radio dichotomy of quasars (Strittmatter et al.
1980): radio-loud quasars (RLQs) with R>10 (0.13) and radio-quiet quasars (RQQs) with R<10
(100-1000); as radio power is concerned the
division is Lr = 1025 W Hz-1
- 8%±1% 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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Introduction – jets.
Owen (NRAO), Biretta (STScI) et al.
M87 from 200 000 to 0.2 ly
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Jets – radio observations.
- highly collimated, < few degrees, (unresolved
transverse structure) flow often showing apparent
supeluminal motion (Cohen et al. 1977)
- apparent velocities 0-15c reaching >30c, 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.
Vermeulen et al. 2003
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)
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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
Marshall et al. 2005; Schwartz et al. 2005
(Warrall astro-ph/0412532)
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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 1045 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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Jets – X-ray observations.
Siemiginowska et al. 2002
- PKS 1127-145 at z=1.187
- offsets as possible indicators of acceleration in the wake of the
shock (Hardcastle et al. 2003)
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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 >107
- luminosity 1.5x1043 erg/s
- knots may indicate helical
structure
3C 273; Marshall et al. 2001
higher energies - [Hudec's talk; Benbow's talk]
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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
Perley et al. 1984
(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
Cawthorne & Gabuzda 1996
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Polarization.
- circular polarization detected only in
pc scale jets (>20 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
3C 273; Homan & Wardle 1999
(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 84; Homan & Wardle 2004
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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 jet:electro-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)
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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
radio-loud PKS 1020-103
radio-quiet 0204+292
- 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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Host galaxies.
- RL are never found in spiral galaxies
- exception 0313-192
- 200kpc FRI source at z=0.067 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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
High-z quasars.
- quasars vs. normal galaxies
- over 900 z>4 quasars known (z>5 –
50; z>6 8) (Fan 2004)
- emission lines and continuum
properties (optical, X-ray) of high-z
quasars exhibit no significant
evolution as compared to low redshift
VLA; Frey et al. 2005
(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
SDSS; Fan et al. 2001
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 z=5.77, but no evidence
for extended emission
Chandra; Brandt et al. 2002
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
High-z quasars.
- for a long time there was no
extended X-ray emission from z>4 RL
quasars – problem for IC/CMB model
Cheung 2004
(Bassett et al. 2004)
Siemiginowska et al. 2003
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
High-z quasars.
- for even higher redshifts the only suspect
is SDSS 1306 at z=5.99, but
Schwartz et al. 2004
- 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
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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)
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy