RADIO-LOUD ACTIVE GALACTIC NUCLEI Rafal Moderski Nicolaus Copernicus Astronomical Center, Warsaw

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

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.


Outline.

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 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

Introduction – jets.


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)

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

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. 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

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

Jets – X-ray observations.


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)

- 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



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)

Jets – multiwavelength.


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

Polarization.


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

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)

Polarization.


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

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)

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

Dunlop et al. 2003

radio-loud PKS 1020-103 radio-quiet 0204+292

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

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 (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

High-z quasars.


- 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

High-z quasars.


- 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

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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RADIO-LOUD ACTIVE GALACTIC NUCLEI Rafal Moderski Nicolaus Copernicus Astronomical Center, Warsaw