RADIO-LOUD ACTIVE GALACTIC NUCLEI Rafal Moderski Nicolaus Copernicus Astronomical Center, Warsaw
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Transcript of RADIO-LOUD ACTIVE GALACTIC NUCLEI Rafal Moderski Nicolaus Copernicus Astronomical Center, Warsaw
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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
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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
Outline.
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Introduction – radio loudness.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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 R>10 (0.1-3) 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]
Rf 5GHzf OIII
Miller, Rawlings & Saunders 1993; Rawlings 1994
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Introduction – jets.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Willis et al. 1982; Perley & Bridle 1984; Perley, Bridle & Willis 1984;Cohen & Readhead 1979; Bridle & Perley 1984
Sanders et al. 1989
- 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)
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Introduction – jets.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, ItalyOwen (NRAO), Biretta (STScI) et al.
M87 from 200 000 to 0.2 ly
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Jets – radio observations.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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. 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.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Marshall et al. 2005; Schwartz et al. 2005
- 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)
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- 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)
Jets – X-ray observations.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Sambruna et al. 2002
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Jets – X-ray observations.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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)
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Jets – multiwavelength.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
3C 273; Marshall et al. 2001
1.647GHz Merlin HST Chandra
higher energies - [Hudec's talk; Benbow's talk]
- 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
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Polarization.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
Perley et al. 1984
- 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
Cawthorne & Gabuzda 1996
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Polarization.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
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.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
3C 273; Homan & Wardle 1999
- 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 (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
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Jet composition.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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)
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Host galaxies.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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
Dunlop et al. 2003
radio-loud PKS 1020-103 radio-quiet 0204+292
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Host galaxies.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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
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High-z quasars.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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 (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 z=5.77, 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.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- for a long time there was no extended X-ray emission from z>4 RL quasars – problem for IC/CMB model (Bassett et al. 2004)
- also 1745+624 at z=3.889 and PMN J2219-2719 at z=3.634 (Cheung et al. 2005)
Siemiginowska et al. 2003
Cheung 2004
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High-z quasars.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- for even higher redshifts the only suspect is SDSS 1306 at z=5.99, 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
Schwartz et al. 2004
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Summary.
XXXXth Recontres de Moriond “Very High Energy Phenomena in the Universe”, La Thuile, Italy
- 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)