Continuo Infrarosso
IR puo’ essere non termico (sincrotrone) o termico. Importante
slope del cut off submm
Se sincrotrone auto-assorbimento a = -2.5
Il minimo a 1 micro suggerisce termico
Variabilita’ (dimensioni) da indicazioni discordanti
Recenti dati ISO suggeriscono IR termico in radio quieti QSO
mentre flat spectrum radio QSO hanno emissione non termica
dominante
Recent result: Baldi et al. arXiv:1010.5277
Usando HST osservazioni di 100 3C sources si ricava che:
FR I: The correlation among near IR, optical, and radio nuclear
luminosity  non thermal origin (IR)
FR II con righe di emissione deboli (low-ionization galaxies LIG):
sono indistinguibili da FR I  stesse proprieta’
FR II con righe allargate (BLO): unresolved near IR nucleus +
large near IR excess dominant  hot circumnuclear dust
(confermato da spettro e SED)
FR II con righe strette ma luminose (high-ionization galaxies HIG)
simili ma fainter di BLO  substantial obscuration + reflection
Scale di grandezza
SMBH
Accretion Disk
Compact radio VLBI core
BLR
Toro molecolare
NLR
Host Galaxy
Radio Lobi
≈ AU
1 mpc
0.1 pc
1 pc
100 pc
1 Mpc
Disk Signatures
• A relatively small subset
of AGNs have doublepeaked profiles that are
characteristic of
rotation.
– Disks are not simple; nonaxisymmetric.
– Sometimes also seen in
difference or rms spectra.
• Disks can’t explain
everything…
NGC 1097
Storchi-Bergmann et al. (2003)
Continuo Banda Radio
Importante storicamente e non, ma in Lbolometrica contribuisce
poco a causa della sua bassa energia
Temperatura di Brillanza: intensita’ di sorgente radio dipende da
flusso e diametro angolare da cui proviene. Con Tb intendo la
temperatura che dovrebbe avere un CN per irradiare lo stesso
flusso.
I = F/πθ2 = B = 2kTb/2
F = flusso osservato monocromatico; θ diametro angolare della
sorgente. Si ottiene T ≈ 1011 – 1012 K che chiaramente indica
una origine non termica
Esiste una Tb massima dell’ordine di 1012 K in quanto
densita’ energia del campo magnetico:
Umag = B2/8π controlla rate delle perdite di sincrotrone
Con densita’ di energia Urad = 4πJ/c
Quando Urad e’ al punto che supera Umag inizia ad essere rilevante
l’interazione di Compton inverso.
Poiche’ non vediamo una intensa radiazione in banda gamma significa
che:
Urad/Umag < 1 che corrisponde a Tmax ≈ 1012 K (catastrofe Compton)
Nuclei radio: sorgenti compatte su risoluzione angolare arcsecond
con alta Tb e spettro piatto (piccole dimensioni angolari).
Ma spettro piatto + alta variabilita’ indicano presenza di strutture
su piccola scala quindi con T tale da dare catastrofe Compton
Vedremo la soluzione grazie a alta risoluzione  VLBI
Risoluzione angolare: R = 1.22 lambda/D in radianti
Lambda e D stessa unita’ di misura!
occhio D= 8 mm R = 17.3” ma retina degrada a 1’
Telescopio 4 m puo’ arrivare a 0.035” ma seeing….
Radio non ha grossi problemi con atmosfera a frequenze
fino a 22 GHz per cui R meglio di 1 mas
ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY
Il Radiotelescopio
SubSimile a telescopio ottico!
riflettore
Sostegno
Accuratezza Specchio  0.1 
Ricevitori
RADIOASTRONOMY
ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY
Importanti
D= 30 del
m telescopio
30’
Banda radio:caratteristiche
 = 20 cm
10’
D= 80 m
Sensibilità  D2
D=700 m
1’
Potere Risolutore  /D
Pupilla:  ~ 0.001 mm
D = 5 mm
RADIOASTRONOMY
1’
Arecibo
Green
Bank (WEST VIRGINIA)
Effelsberg
(Portorico)
100x110
m
Parkes
Jodrell Bank
(Bonn)
300
m
(Agosto
2000)
(Australia
(Manchester
)
)
64 m
75 m
100 m
ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY
L’ INTERFEROMETRO
Potere Risolutore: ~ /d
(d = distanza antenne)
Sensibilità: ~ N x D2
(N=numero antenne)
RADIOASTRONOMY
d
ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY
Very Large Array (New Mexico)
27 antenne di 25 m
Dmax ~ 30 km
Westerbork (Olanda)
14 antenne di 25 m
Dmax ~ 3 km
ATCA (Australia)
6 antenne di 22 m
1” a 20 cm
Dmax ~ 6 km
RADIOASTRONOMY
ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY
European VLBI Network – EVN
18 Antenne
RADIOASTRONOMY
ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY
Very Long Baseline Array (VLBA)
• Dal 1993
• 10 antenne da
25-m sparse tra
USA e Canada
• Correlatore a
Socorro
RADIOASTRONOMY
EVN
Very Long Baseline Interferometry : VLBI
V
L
B
A
Spatial VLBI
1144+35
3C 264
z
1”
1 mas
0.06
1.6 kpc
1.6 pc
Cyg A
0.16
3.6 kpc
3.6 pc
3C 273
0.5
7.1 kpc
7.1 pc
3C 48
Resolving Power
radians
 = 20 cm, D = 1000 km   = 0.04”
VLBI studies of radio galaxy nuclei :
one of the most important results is the
detection of proper superluminal motion
Expansion of about
6 pc in 3.5 years:
 velocity  6c
QUASAR
1642+690
z = 0.75
The southernmost feature is moving at about 9c (Venturi et al. 1997)
QUASAR
1928+738
z = 0.302
Aug 97
Sep 01
Observation performed with the space VLBI at 5 GHz
(Murphy et al. 2003)
SUPERLUMINAL MOTION
By the time that light leaves from position
(2), light emitted from position (1) will have
travelled a distance AC
The difference in arrival time for the
observer is :
AC  AB ct  vtcos
t(OBS) 

c
c
The apparent velocity as seen by the
observer is
BD
vtsin 
vsin 
v(OBS) 


t(OBS) t(OBS) 1 - v cos 
c
 sin 
app 
1   cos 
For example :  = 10o and v = 0.999c
then : v(OBS) = 10.7 c
The detection of superluminal motions and
of one-sided jets in the majority of both
low power and high power radio galaxies
indicates that the jets at their basis are
all strongly relativistic
Effetto Doppler e boosting relativistico
Se una sorgente si muove con v = βc in una direzione che forma
angolo θ con la linea di vista abbiamo
o = e/((1-βcosθo)) = e D
Dove  e’ il fattore di Lorentz e
D = 1/((1-βcosθo)) e’ il Doppler factor (velocita’ positiva in
avvicinamento D > 1 quando β > 0 e o > e
Se velocita’ bassa  ≈ 1 e D  (1 + β cosθo) Doppler classico
Consideriamo sorgente con Luminosita’ totale Le e luminosita’
monocromatica L(e)
La potenza irradiata in banda e sara’ ricevuta in banda
o = e D
Consideriamo come varia luminosita’ – essendo radiazione per unita’
di tempo teniamo conto
trasformazione energia fotoni
o = e x D
Trasformazione dei tempi
dto = dte - dte  v cosθ/c = dte(1 – β cosθ) = dte/D
sorgente si e’ avvicinata tra tempo emissione 2 fotoni
La radiazione ricevuta in superficie unitaria compresa in cono angolo
solido do che sara’ diverso da de
do = de/D2
si ottiene da aberrazione relativistica ricordando che do ≈ π dθo2
In conclusione
Lo = Le x D4
Boosting relativistico o Doppler boosting o relativistic beaming
Se lavoriamo con luminosita’ monocromatiche
Lo(o)do = Le(e)de x D4
da cui
Lo(o) = Le(e) x D3
Se lo spettro e’ di sincrotrone L()  - possiamo scrivere
Lo(o) = Le(o) x D3+ = Le(o) x D4 D-(1-)
Il termine D-(1-) e’ noto come correzione K
JET RELATIVISTIC EFFECTS (DOPPLER BOOSTING) :
Doppler factor
Jet pointing toward the observer is AMPLIFIED
From the ratio between the approaching and the receding jet,
the jet velocity and orientation can be constrained
JET SIDEDNESS RATIO
Ma se parliamo di getti o plasmoidi quasi continui si parla di
brillanza: la lunghezza della struttura nella direzione
del moto e’ influenzato da D ma lo spessore della struttura no
(moto unidimensionale) ne segue che:
Jet sidedness
Se  = 5 (β = 0.98) e  = 0.7 e θ = 0 risulta Ba/Br = R = 2 x 104
Ne consegue che dati 2 getti intrinsecamente uguali vedo solo
quello che si muove verso di me e non l’altro
From the jet to cj brightness ratio R we derive:
 1   cos  

R  
 1   cos  
2 
Main problem: low luminosity radio jets do not give strong
constraints: in 3C264 the highest j/cj ratio is > 37
corresponding to θ < 52o and β > 0.62
FR I - 3C 449
FR II - 3C 47
Radio image of the FR II radio galaxy Cygnus A.
This galaxy also has HUGE radio lobes.
The lobes occur where the jets plow into intracluster gas.
The thin line through the galaxy is a jet ejected from the nucleus.
FR I radio galaxy: most of the energy comes from a small nucleus with a
halo of weaker emission in a halo around the nucleus.
Visible image of the core-halo (FR I) radio galaxy M87.
This giant elliptical (E1) galaxy is ~100 Kpc across.
It has a “jet” of material coming from the nucleus.
Close-up view of the jet in M87 at radio wavelengths.
galaxy nucleus,
i.e. the radio core
The jet is apparently a series of distinct “blobs”, ejected by the
galaxy nucleus, and moving at up to half the speed of light.
The jet and nucleus are clearly non-stellar.
Quasar
BL Lac
MK 501
Radio Galaxy
1144+35
BL Lac 0521-365
Radio core dominance
Given the existence of a general correlation between the core
and total radio power we can derive the expected intrinsic core
radio power from the unboosted total radio power at low
frequency.
log Pc  0.62  0.04log Ptot  7.6  1.1
Pc = observed core radio power at 5 GHz
Ptot = observed total radio power at 408 MHz
La potenza del core e’ legata alla presenza del jet relativistico
la potenza totale NO – a bassa frequenza cosi core non pesa
essendo auto-assorbito
Alta e bassa
Potenza:
Relativistici
Su scala piccola
The comparison of the expected intrinsic and observed core radio power will
constrain β and θ.
A large dispersion of the core radio power is expected because of the
dependance of the observed core radio power with θ.
From the data dispersion we derive that Г has to be > 2 and < 10
Pc = Pi D(2+ )
Pbest-fit = P(60) = Pi D(2+ ) = Pi/2+(1-β cosθ)2+ = con θ = 60
Pi/2+(1-β/2)2+
Pi = P(60)/D(2+ ) da cui Pi = P(60) 2+(1-β/2)2+
e
Pc = P(60) (1-β/2)2+ / (1-β cosθ)2+
Assumendo  = 0 (nucleo)
Pc = P(60) (1-β/2)2 / (1-β cosθ)2
(Pc/P(60))0.5 = (1-β/2)/ (1-β cosθ)
Pc da osservazioni
P(60) da Ptot e best fit
Possiamo assumere tutti i getti circa stessa velocita  posizione
punti solo legati a orientazione MA dispersione dipende da velocita’
dei getti
Problema: variabilita’ !!!!
Conseguenze di tempi diversi
Getto relativistico in avvicinamento insegue suoi fotoni per cui
intervalli di tempo non si conservano
Se emesso segnale a tempo t=0 e segnale successivo a intervallo
tempo ta, osservatore riceve segnale a t2 = ta+(d – vta cosθ)/c
Osservatore vede 2 segnali a t = t2 – t1 = ta(1 – v/c cosθ) =
ta(1 – β cosθ)
Se 2 getti o lobi intrinsecamente simmetrici si muovono relativist.
appariranno diversi perche li vediamo a t intrinseco diverso
a = approaching ed r receading
ta = t /(1-β cosθ) tr = t /(1+β cosθ)
Essendo L’a = La sinθ = vta sinθ e L’r = Lr sinθ = vtr sinθ
L = Lunghezza (size)
risulta che:
Arm length ratio
By comparison of the size of the approaching (La)
and receding (Lr) jet we derive:
o anche La/Lr = L’a/L’r = θa/θr = Da/Dr
Lobi radio:
Mediano asimmetria flussi = 1.6
se dovuto a moto relativistico ne derivo β cosθ ≈ 0.06
da cui β < 0.1
Inoltre risulta che
Sa/Sr = (θa/θr)3+ da cui lobo piu’ lontano dal nucleo dovrebbe
essere piu’ luminoso, ma cio’ non verificato anzi contrario
Tutto porta a derivare velocita’ espansione lobi < 0.1c
Tale velocita’ e’ anche in accordo con diametro e stima eta’ della
radio sorgente
THE MEASUREMENT OF THE JET VELOCITY
Proper Motion
In some sources proper motion has been detected allowing
a direct measure of the jet apparent pattern velocity.
The observed distribution of the apparent velocity shows a
large range (e.g. Kellerman et al. 2000)
From the measure of the apparent velocity we can derive
constraints on β and θ:
But are bulk and pattern velocity correlated????
In a few cases where proper motion is well defined there is a
general agreement between the highest pattern velocity and
the bulk velocity:
Ghisellini et al. 1993
Cotton et al. 1999 for NGC 315
Giovannini et al. 1999 for 1144+35
However in the same source we can have different pattern
velocities as well as standing and high velocity moving
structures
In some well studied sources the jets show a smooth and uniform
surface brightness  no proper motion visible
e.g. Mkn 501 (Giroletti et al. 2003, ApJ)
βamax = β ≈  per v ≈ c
Il massimo si ha per cos θ = β ossia sen θ = 1/
(θ ≈ 1/ per  grandi)
Se il redshift e’ molto elevato occorre inserire correzione
relativistica perche’ tutto si sta allontanando da noi con
moto relativistico
Sempre: v = βc e’ la velocita’ del blob rispetto al nucleo
della sorgente
Vedi astro-ph/0407478, 9-9-04
On the parsec scale it shows a core, a strong extended jet and
a short cj
counterjet
flat spectrum core
main jet
Superluminal motion
Well defined components – 11 epochs from 1991 to 2002
Only high quality data:
jet: 5 and 8.4 GHz data
cj 8.4 GHz only
Jet: βapp = 2.7 constant
All components constant
velocity
cj side βapp = 0.3
Since we know the j and cj proper motion according to
Mirabel et al. 1994 we can derive the jet orientation:
μa = β senθ/(1 – β cosθ) c/D
μr = β senθ/(1 + β cosθ) c/D
che diventano
β cosθ = (μa – μr) /(μa + μr) = 0.8
D  0.5c tan  a  r a r 
1
.
cgs e moti propri in radianti s-1
Da cui D <= c/(μaμr)0.5 (velocita’ massima e’ c)
(distance of the superluminal galactic source)
From the j-cj arm ratio ( about 10) we derive
β cosθ = 0.8
in agreement with the measured pattern velocity
Shear-layer δ = 2.4 - boosted
core
If the inner spine is moving with e.g.
Г = 15 the corresponding Doppler
factor is 0.7 – deboosted.
A fast spine and a lower velocity
shear layer can explain the limb
brightened structure.
If the external region started with the same velocity of the
inner spine, its velocity decreased from 0.998 to 0.88c in less than
100 pc. This suggest a velocity structure already present at the
jet beginning.
Results
From our study on sources from the B2 and 3CR catalogues
and from literature data we found that:
- In all sources pc scale jets move at high velocity. No correlation
has been found with core or total radio power
- We used the jet velocity and the corresponding orientation to
derive the Doppler factor for each source:
  ((1   cos  ))
1
and the corresponding intrinsic core radio power:
=0
M87
3C192
The line is the general correlation between the core and total
radio power. Points in the left side (observed data) show the
expected dispersion because of different orientation. Note
that we started to observe sources with brighter core.
In the right figure we plotted the derived intrinsic core radio
power. We have here a small dispersion since we removed the
spread due to different orientation angles.
Struttura dei nuclei radio
Strutture compatte auto assorbite
Non vediamo ‘core’ ma base del getto
Autoassorbimento: Tb simile a temperatura cinetica elettroni
relativistici
Spettro a campana radiosorgente opaca a se stessa
in regime opaco flusso cresce come 2.5,
dove la sorgente e’ trasparente flusso cala come -
Indicando con max ed Smax la frequenza dove lo spettro
raggiunge il massimo e con Smax il flusso corrispondente
abbiamo
H(gauss) ≈ 3.2 10-5(θ(mas))4(max(GHz))5(Smax(Jy))-2 D/(1+z)
con D = fattore Doppler
Dove θ e’ il diametro angolare nella zona di transizione
quindi abbiamo stima del campo magnetico
viceversa assumendo il campo magnetico di equipartizione
possiamo stimare diametro angolare della rs
Spettro = somma spettri di singole componenti da cui spettro piatto
3C 338 a FR I radio galaxy
3C 452 a NL FR II radio galaxy
Variabilita’
Compatte mostrano variabilita’ piu’ o meno marcata in tutte le
bande
A frequenze < 1 GHz scintillazione interstellare
Variabilita’ a lungo periodo
ad alta frequenza intrinseco: modello nube inizialmente opaco
che espande e diventa trasparente a frequenze sempre piu’
basse e con flussi sempre minori (perdite adiabatiche)
La variabilita’ avviene a tempi diversi a diverse frequenze
Variabilita’ a corto periodo
Assumendo che dimensioni lineari sorgente siano < cTv dove Tv
e’ il tempo della variabilita’, ne derivano dimensioni angolari
< 10-4 10-5 arcsec
Da dimensioni angolari cosi piccole risulta che
I = F/πθ2 = B = 2kTb/2
Se e’ θ piccolo e/o  e’ grande possiamo ottenere Tb() > 1012 K
Per cui 1) emissione coerente – difficile per regioni cosi grandi
2) diametri sottostimati
Infatti T alta implica radiazione alta energia non osservata e vita
breve della rs
Possibile soluzione nube in espansione in moto relativistico verso
di noi
Tbo = Tbi x D
AGN Unification
History
The present status
What’s all this Unification?
• Historically it is attempt to explain as much
as the spread of observational properties
as possible in terms of orientation effects.
– Assume some axis; i.e. rotation
• More generally, it is an attempt to explain
the diversity of observational properties in
terms of a simple model
Introduction
• AGN are not spherically symmetric and thus
what you see depends on from where you view
them. This is the basis of most unification
models.
• It was the discovery of superluminal motion and
the interpretation in terms of bulk relativistic
motion of the emitter that first made people
realize that orientation in AGN was important.
• I will outline the consequences of Doppler
boosting, describe the historical development of
schemes and then review the modern evidence.
– N.B. Relativistic beaming is not the only mechanism
that can make AGN emission anisotropic
Doppler boosting
• When an emitting body is moving
relativistically the radiation received by an
observer is a very strong function of the angle
between the line of sight and the direction of
motion.
sobs  sem ( 2  )
– The Doppler effect changes the energy and
frequency of arrival of the photons.
– Relativistic aberration changes the angular
distribution of the radiation.
Parent populations
• To every beamed source there will be
many unbeamed sources – the parent
population.
• How to identify the parent population?
– Look at some emission that’s isotropic; e.g.
radio lobe emission, far infrared emission,
narrow-line emission, etc in the beamed
population and look for another population
having the same luminosity function for the
isotropic emission.
History of Unification
• Rowan-Robinson (1976, ApJ, 213,635) tried to
unify Seyfert galaxies and radio sources.
– Mostly wrong – no beaming
– But the importance of dust and IR emission correct.
• Blandford and Rees (Pittsburgh BL Lac meeting
1978) laid the foundations for beaming
unification. (Radio loud only).
History continued
• Scheuer and Readhead (1979, Nature,277,182)
proposed that radio core-dominated quasars and radio
quiet quasars could be unified – the former being
beamed versions of the latter.
• Orr and Browne (1982,MNRAS,200,1067 ) realized
that the Scheuer and Readhead scheme could not
work because MERLIN and VLA had shown that most
of the core-dominated quasars had extended
(isotropic) radio emission and thus their parent
population could not be radio quiet. We looked for a
non-radio quiet parent population
– Proposed core-dominated/lobe-dominated unification for
quasars
Radio Galaxy/Quasar
Unification
(Both are FR2s)
• Widely discussed before, but first published by
Barthel (1989, ApJ, 336,606) – an extension of coredominated/lobe-dominated quasar unification.
• Quasars have strong continuum and broad lines and
radio galaxies (FR2s) have little continuum (other than
starlight) and no broad lines.
• How could they be the same thing? Only if one could
hide the quasar nucleus with something optically thick
(a molecular torus).
– N.B. In a parallel line of development Antonucci and Miller
had discovered polarized broad lines in the Seyfert 2
NGC1068 which they interpreted as being scattered nuclear
radiation from a hidden BLR.
BL Lacs and FR1 RGs
• Similar arguments apply to these intrinsically
lower luminosity objects; BL Lacs are the
beamed cores of FR1 RGs. (Note FR1 RGs
generally have only weak and narrow emission
lines and BLLacs are almost lineless.)
•
•
•
•
Blandford and Rees (1978)
Browne (1983, MNRAS,204,23)
Antonucci and Ulvestad (1985,ApJ,294,158)
Padovani and Urry (1991, ApJ,368,373)
Evidence for BL Lac/FR1
unification
• The statistics look ok (Browne; Padovani and
Urry) for reasonable Lorentz factors
• The required relativistic jets are seen in a few
FR1s, most notably in M87 (Biretta AJ,520,621).
• The strength of optical cores in FR1s seems to
correlate with the strength of the radio core
consistent with both being beamed (Capetti
&Celotti,1999,MNRAS,303,434, Chiaberge et al.
2000,A&A,358,104)
=> No hidden BLR in FR1s (but BL Lac itself has a
broad line)
HST Image of jet in M87
• M87 is an FR1 radio
galaxy
• Superluminal motion
has been detected in
both radio and optical
Evidence for superluminal
motion in M87
Correlation between optical nuclear and radio core
luminosities (Chiaberge et al,A&A,358,104)
NGC6251
• HST image of the
optical core.
• Despite dust lane
(dark band) the core
is clearly visible
• The strength of cores
correlated with that of
radio core
Optical nuclei are very
common.