Continuo Infrarosso IR puo’ essere non termico (sincrotrone) o termico. Importante slope del cut off submm Se sincrotrone auto-assorbimento a = -2.5 Il.

Presentazione sul tema: "Continuo Infrarosso IR puo’ essere non termico (sincrotrone) o termico. Importante slope del cut off submm Se sincrotrone auto-assorbimento a = -2.5 Il."— Transcript della presentazione:

1 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

2 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

3 Scale di grandezza SMBH ≈ AU Accretion Disk 1 mpc Compact radio VLBI core 0.1 pc BLR 1 pc Toro molecolare 100 pc NLR Host Galaxy Radio Lobi 1 Mpc

4 Disk Signatures A relatively small subset of AGNs have double- peaked profiles that are characteristic of rotation. –Disks are not simple; non- axisymmetric. –Sometimes also seen in difference or rms spectra. Disks can’t explain everything… NGC 1097 Storchi-Bergmann et al. (2003)

5 Continuo Banda Radio Importante storicamente e non, ma in L bolometrica 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 T b intendo la temperatura che dovrebbe avere un CN per irradiare lo stesso flusso. I = F /πθ 2 = B = 2kT b / 2 F = flusso osservato monocromatico; θ diametro angolare della sorgente. Si ottiene T ≈ 10 11 – 10 12 K che chiaramente indica una origine non termica

6 Esiste una T b massima dell’ordine di 10 12 K in quanto densita’ energia del campo magnetico: U mag = B 2 /8π controlla rate delle perdite di sincrotrone Con densita’ di energia U rad = 4πJ/c Quando U rad e’ al punto che supera U mag inizia ad essere rilevante l’interazione di Compton inverso. Poiche’ non vediamo una intensa radiazione in banda gamma significa che: U rad /U mag < 1 che corrisponde a T max ≈ 10 12 K (catastrofe Compton) Nuclei radio: sorgenti compatte su risoluzione angolare arcsecond con alta T b 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

7 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

8 Accuratezza Specchio  0.1 RADIOASTRONOMY ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY Il Radiotelescopio Simile a telescopio ottico! Sub- riflettore Sostegno Ricevitori

9 Importanti caratteristiche del telescopio Sensibilità  D 2 Potere Risolutore  /D RADIOASTRONOMY ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY Banda radio: = 20 cm D= 80 m 10’ D= 30 m 30’ D=700 m 1’ Pupilla: ~ 0.001 mm D = 5 mm 1’

10 Parkes ( Australia ) 64 m Jodrell Bank ( Manchester ) 75 m Effelsberg ( Bonn ) 100 m Green Bank ( WEST VIRGINIA ) 100x110 m ( Agosto 2000) Arecibo (Portorico) 300 m

11 RADIOASTRONOMY ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY L’ INTERFEROMETRO Potere Risolutore: ~ /d (d = distanza antenne) Sensibilità: ~ N x D 2 (N=numero antenne) d

12 Westerbork (Olanda) 14 antenne di 25 m D max ~ 3 km RADIOASTRONOMY ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY ATCA (Australia) 6 antenne di 22 m D max ~ 6 km Very Large Array (New Mexico) 27 antenne di 25 m D max ~ 30 km 1” a 20 cm

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14 RADIOASTRONOMY ISTITUTO DI RADIOASTRONOMIA, INAF - ITALY European VLBI Network – EVN 18 Antenne

15 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

16 Very Long Baseline Interferometry : VLBI VLBAVLBA VLBAVLBA Spatial VLBI EVN

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18 1144+35

19 3C 264

20 z1” 1 mas 0.06 1.6 kpc 1.6 pc 0.16 3.6 kpc 3.6 pc 0.5 7.1 kpc 7.1 pc Cyg A 3C 273 3C 48 Resolving Power radians = 20 cm, D = 1000 km   = 0.04”

21 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 Expansion of about 6 pc in 3.5 years:  velocity  6c

22 The southernmost feature is moving at about 9c (Venturi et al. 1997) QUASAR 1642+690 z = 0.75

23 Observation performed with the space VLBI at 5 GHz (Murphy et al. 2003) Observation performed with the space VLBI at 5 GHz (Murphy et al. 2003) QUASAR 1928+738 z = 0.302 Aug 97 Sep 01

24 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 : 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 : The apparent velocity as seen by the observer is The apparent velocity as seen by the observer is SUPERLUMINAL MOTION For example :  = 10 o and v = 0.999c then : v(OBS) = 10.7 c For example :  = 10 o and v = 0.999c then : v(OBS) = 10.7 c

25 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

26 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-βcosθ o )) = e D Dove  e’ il fattore di Lorentz e D = 1/(  (1-βcosθ o )) e’ il Doppler factor (velocita’ positiva in avvicinamento D > 1 quando β > 0 e o > e Se velocita’ bassa  ≈ 1 e D  (1 + β cosθ o ) Doppler classico Consideriamo sorgente con Luminosita’ totale L e e luminosita’ monocromatica L( e ) La potenza irradiata in banda  e sara’ ricevuta in banda  o =  e D

27 Consideriamo come varia luminosita’ – essendo radiazione per unita’ di tempo teniamo conto trasformazione energia fotoni o = e x D Trasformazione dei tempi dt o = dt e  - dt e  v cosθ/c = dt e  (1 – β cosθ) = dt e /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 /D 2 si ottiene da aberrazione relativistica ricordando che d  o ≈ π dθ o 2

28 In conclusione L o = L e x D 4 Boosting relativistico o Doppler boosting o relativistic beaming Se lavoriamo con luminosita’ monocromatiche L o ( o )d o = L e ( e )d e x D 4 da cui L o ( o ) = L e ( e ) x D 3 Se lo spettro e’ di sincrotrone L( )  -  possiamo scrivere L o ( o ) = L e ( o ) x D 3+  = L e ( o ) x D 4 D -(1-  ) Il termine D -(1-  ) e’ noto come correzione K

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30 JET RELATIVISTIC EFFECTS (DOPPLER BOOSTING) : JET RELATIVISTIC EFFECTS (DOPPLER BOOSTING) : Jet pointing toward the observer is AMPLIFIED Doppler factor

31 JET SIDEDNESS RATIO From the ratio between the approaching and the receding jet, the jet velocity and orientation can be constrained From the ratio between the approaching and the receding jet, the jet velocity and orientation can be constrained 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:

32 Jet sidedness Se  = 5 (β = 0.98) e  = 0.7 e θ = 0 risulta B a /B r = R = 2 x 10 4 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: Main problem: low luminosity radio jets do not give strong constraints: in 3C264 the highest j/cj ratio is > 37 corresponding to θ 0.62

33 FR I - 3C 449FR II - 3C 47

34 Radio image of the FR II radio galaxy Cygnus A. The lobes occur where the jets plow into intracluster gas. ~1 Mpc This galaxy also has HUGE radio lobes. The thin line through the galaxy is a jet ejected from the nucleus.

35 This giant elliptical (E1) galaxy is ~100 Kpc across. It has a “jet” of material coming from the nucleus. Visible image of the core-halo (FR I) radio galaxy M87. 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.

36 Close-up view of the jet in M87 at radio wavelengths. ~2 kpc 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.

37 BL Lac 0521-365 BL Lac MK 501 Radio Galaxy 1144+35 Quasar

38 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. Radio core dominance P c = observed core radio power at 5 GHz P tot = 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

39 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 Alta e bassa Potenza: Relativistici Su scala piccola

40 Pc = Pi D (2+  ) P best-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’ !!!!

41 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 t a, osservatore riceve segnale a t 2 = t a +(d – vt a cosθ)/c Osservatore vede 2 segnali a  t = t 2 – t 1 = t a (1 – v/c cosθ) = t a (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 t a =  t /(1-β cosθ) t r =  t /(1+β cosθ) Essendo L’ a = L a sinθ = vt a sinθ e L’ r = L r sinθ = vt r sinθ L = Lunghezza (size)

42 By comparison of the size of the approaching (L a ) and receding (L r ) jet we derive: Arm length ratio risulta che: o anche L a /L r = L’ a /L’ r = θ a /θ r = D a /D r

43 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 S a /S r = (θ a /θ r ) 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

44 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) THE MEASUREMENT OF THE JET VELOCITY

45 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

46 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) β amax =  β ≈  per v ≈ c Il massimo si ha per cos θ = β ossia sen θ = 1/  (θ ≈ 1/  per  grandi)

47 Sempre: v = βc e’ la velocita’ del blob rispetto al nucleo della sorgente Vedi astro-ph/0407478, 9-9-04 Se il redshift e’ molto elevato occorre inserire correzione relativistica perche’ tutto si sta allontanando da noi con moto relativistico

48 On the parsec scale it shows a core, a strong extended jet and a short cj flat spectrum core counterjet main jet

49 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: β app = 2.7 constant All components constant velocity cj side β app = 0.3 Superluminal motion

50 Since we know the j and cj proper motion according to Mirabel et al. 1994 we can derive the jet orientation: μ a = β senθ/(1 – β cosθ) c/D μ r = β senθ/(1 + β cosθ) c/D che diventano β cosθ = (μ a – μ r ) /(μ a + μ r ) = 0.8 cgs e moti propri in radianti s -1 Da cui D <= c/(μ a μ r ) 0.5 (velocita’ massima e’ c) (distance of the superluminal galactic source).

51 From the j-cj arm ratio ( about 10) we derive β cosθ = 0.8 in agreement with the measured pattern velocity

52 Shear-layer δ = 2.4 - boosted 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. core

53 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: and the corresponding intrinsic core radio power:  = 0 Results

54 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. M87 3C192

55 Struttura dei nuclei radio Strutture compatte auto assorbite Non vediamo ‘core’ ma base del getto Autoassorbimento: T b 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 S max la frequenza dove lo spettro raggiunge il massimo e con S max il flusso corrispondente abbiamo H(gauss) ≈ 3.2 10 -5 (θ(mas)) 4 ( max (GHz)) 5 (S max (Jy)) -2 D/(1+z) con D = fattore Doppler

56 3C 452 a NL FR II radio galaxy 3C 338 a FR I radio galaxy 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

57 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 < cT v dove T v e’ il tempo della variabilita’, ne derivano dimensioni angolari < 10 -4 10 -5 arcsec

58 Da dimensioni angolari cosi piccole risulta che I = F /πθ 2 = B = 2kT b / 2 Se e’ θ piccolo e/o e’ grande possiamo ottenere T b ( ) > 10 12 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 T bo = T bi x D

59 AGN Unification History The present status

60 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

61 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

62 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. –The Doppler effect changes the energy and frequency of arrival of the photons. – Relativistic aberration changes the angular distribution of the radiation.

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64 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.

65 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).

66 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

67 Radio Galaxy/Quasar Unification (Both are FR2s) Widely discussed before, but first published by Barthel (1989, ApJ, 336,606) – an extension of core- dominated/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.

68 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)

69 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)

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71 HST Image of jet in M87 M87 is an FR1 radio galaxy Superluminal motion has been detected in both radio and optical

72 Evidence for superluminal motion in M87

73 Correlation between optical nuclear and radio core luminosities (Chiaberge et al,A&A,358,104)

74 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

75 Optical nuclei are very common.