Jet

From accretion/inflows to ejection/outflows
From IN to OUTflows
v/c=0 0.1
0.2 0.3 0.4
OUT
OUT
IN
Magnetic Tower by Kato et al. 2003
(see also Lynden-Bell 2003)
IN
In summary, X-ray diagnostics allow to probe:
Overall wind structure…
Winds/outflows
through blueshifted
absorption lines
Quasar wind model by Elvis 2000
but also inner structure
Accretion/inflows
through redshifted Fe
emission/abs. lines
v/c= 0 0.1 0.2 0.3 0.4
Magnetic Tower by Kato et al. 2003
(see also Lynden-Bell 2003)
X = termico
Radio e
Gamma lontani
X non termico da
Jet
Pseudocore & Standing Shocks
"Pseudocore" on VLBI images is either:
1.  ~ 1 surface
2. First standing (oblique or conical) shock outside  ~ 1 surface
Proposed by Daly & Marscher 1988 ApJ
Pseudocore
at ~3 mm
 >1 at
~3 mm
At ~1 cm
 >1 at
~1 cm
At ~4 cm
 >1 at
~4 cm
Prediction: Moving knots can appear a bit upstream of
pseudocore if already loaded with high-E electrons
Stationary feature w/ variable pol.
Pseudocore & "True" Core at mm Wavelengths
"True" core (seen at  < ~1 mm): end of flow acceleration zone
Perhaps can probe acc. zone at ~ 1 mm & FIR (see Jorstad et al. 2007, AJ, in press)
CORE LOCATION: approaching the SMBH
Hada et al. 2012, observed
M87 at different frequencies
with VLBA. They estimated
the core shift because of
different optical depths.
The SMBH is at 14-23 Rs from
the 43GHz core
New observations with VLBA
and the GBT have been obtained
but not yet scheduled to observe
at 86 GHz and to obtain
images in the accretion region
Large scale jet direction
INNER JET PROPERTIES: jet launching region
R 0.56±0.03
parabolic
Conical shape
Non spinning
Max spinning
Energia prodotta nel nucleo viene portata ai lobi esterni
attraverso un canale in cui energia viene trasportata ad altissima
efficienza. Perdite per quanto piccole fanno si che il jet sia visibile.
Simmetria:
Si osserva asimmetria maggiore vicino al nucleo, cala con la distanza
--FR I one-sided entro 1 kpc poi tendono a simmetria
--FR II tipicamente one-sided anche su grande scala e jet verso hot
spot piu’ brillante
-- accordo scala pc e kpc
Effetti relativistici anche su grande scala in accordo con effetto
Garrington-Laing, in accordo con pc e tenuto conto della
simmetria dei lobi
STUDIES ON ALL SCALES:
FROM KPC TO PC
 510 kpc
 17 kpc
 17 kpc
28 pc
z = 0.01
(Schwarzchild radius)
M87 (Virgo A)
FRI sources: jet deceleration
There is good evidence that FRI jets are
highly relativistic on pc scales (and direct
measurement of motions at >5c in M 87 on
kpc scales).
They appear to decelerate to sub-relativistic
speeds on scales ~1 - 30 kpc.
Compare approaching and receding jets
(assumed identical) to deduce velocity field =>
spine/shear layer picture.
More ingredients (FRI)
Tail
Jets
Tail
3C 31 (VLA 1.4GHz; 5.5 arcsec FWHM)
JETS IN FR I :
* LARGE OPENING ANGLE
* TWO-SIDED
* MAGN FIELD  TO JET AXIS
Evidences of a strong jet
Deceleration within 5 kpc from the
core
LOW VELOCITY (Sonic-subsonic):
M  2, v  0.1 c DECREASING
FR I RADIO GALAXIES (LOW VELOCITY JETS) CAN
SHOW DISTORTIONS - OSCILLATIONS - CURVATURES
(INTERACTION WITH THE AMBIENT MEDIUM)
Tailed radio galaxies
NAT - WAT
Total intensity fits
Model
Data
0.75 arcsec FWHM
0.25 arcsec FWHM
Systematic properties of decelerating relativistic jets in low
Luminosity radio galaxies Laing et al. arXiv:1311.1015
Model velocity field
FRII jets
Much less is known about detailed structure,
because of poorer transverse resolution.
Evidence for relativistic velocities (>0.6c) on all
scales in the jets (Wardle & Aaron), and even
beyond the hot-spots in powerful quasars
(Dennett-Thorpe et al. 1997).
As in FRI's, velocity stratification is very likely, so
the jet spines may have even higher speeds.
Ingredients (FRII)
AGN Jet density:
FRII Morphologies
undisturbed
intergalactic gas
“cocoon” (shocked
jet gas)
splash point
backflow
bow shock
Cygnus A (FR II) - VLA, 6cm
JETS IN FR II RADIO GALAXIES :
* VERY COLLIMATED
* ONE-SIDED
* MAGNETIC FIELD PARALLEL TO THE JET AXIS
HIGH VELOCITY (supersonic - relativistic) :
relativistic beaming affects the prominence of the kpc scale
Jets, but less than in the central regions (i.e. Г decreases)
Data are consistent with Г = 2 on the kpc scale.
One-sided kpc scale jet
Da evidenza getti radio su grande scala:
1) Jets in FR I non relativistici dopo alcuni kpc (simmetria,
brillanza, angolo apertura
2) Jets in FR II relativistici su kpc scale: one-sided, brillanza
angolo apertura
Evidenza ulteriore, importante da scoperta emissione X jets su kpc
scale:
2 tipi di getti con emissione X
a) X da sincrotrone – unica power law (richiede riaccelerazione
in loco)
b) X da SSC – elettroni relativistici con radiazione di fondo –
richiede getti relativistici (per vedere fotoni boosted)
Lessons from large scales: complex relation between emission at
different frequencies
3C273:
synchrotron and
inverse Compton
mechanisms may
both be important
at X-ray
wavelengths
Optical
HST
X-ray
Chandra
Radio
MERLIN
 FR I: Jet dominated emission, two-sided jets,
typically in clusters, weak-lined galaxies
 FR II: Lobe dominated emission, one-sided
jets, isolated or in poor groups, strong
emission lines galaxies
Radio vs optical luminosities:
LR  Lopt 1.7
(Owen & Ledlow 1994)
INNER JET PROPERTIES: jet launching region
R 0.56±0.03
parabolic
Conical shape
Non spinning
Max spinning
What Powers Active Galactic Nuclei??
(1) A compact central source
provides a very intense
gravitational field. For active
galaxies, the black hole has
MBH = 106 - 109 Msun
(2) Infalling gas forms an
accretion disk around the
black hole.
(3) As the gas spirals inward,
friction heats it to extremely
high temperatures; emission
from the accretion disk at
different radii (T>104 K)
accounts for optical thru soft
X-ray continuum.
(4) Some of the gas is driven out
into “jets,” focused by
magnetic fields.
How efficient
is the energy
production?
Before disappearing into the event horizon
of a black hole, some fraction of the
infalling mass is converted into energy.
Matter is heated to high temps by
dissipation in accretion disk and radiates
away its gravitational potential energy.
BH radius is Rs=2GM/c2 = 0.25 M8 light
hours (which sets minimum variability
timescale). Smallest stable orbit is at
3Rs. Max efficiency occurs when all
potential energy released during fall from
infinity to 3Rs is extracted. GR gives
efficiency = 6% to 40% depending on BH
rotation. Example: By consuming 1 – 10
solar masses per year, black hole
accretion disk can radiate ~100 – 1000
LMilkyWay.
Fueling Quasars
Energia da conversione di massa in energia
Energia disponibile e’ E = ηMc2
Il rate di energia emessa e’ L = dE/dt = ηc2 dM/dt
dove dM/dt e’ accretion rate
Quindi per una tipica QSS occorre
dM/dt = L/ηc2 ≈ 1.8 x 10-3 (L44/η)
in M●yr-1 accretion rate
In caso di energia gravitazionale cioe’ energia da collasso
U = GMm/r ed L = dU/dt
= gM/r dm/dt = GM/r dM/dt
(energia tipo supernovae)
η e’ proporzionale a M/r = compattezza del sistema
L’efficienza e’ quindi massima nel caso di un BH con
Rs = 2GM/c2 importante e’ il raggio finale nel collasso!
= 3 x 1013 M8 cm = 10-2M8 light days
Poiche’ maggior parte della radiazione ottica e UV avviene
a 5 Rs,  U = GMm/5Rs = GMm/(10GM/c2) = 0.1 mc2
Da cui a 5 Rs η = 0.1
H He e’ 0.007
molto efficiente (ordine di grandezza!)
Se Lqss = 1046 erg s-1  dM/dt ≈ 2M●yr -1
Eddington accretion rate dMe/dt = Le/ηc2 = 2.2 M8M●yr-1
dMe/dt e’ il massimo accretion rate possibile in caso di
semplice simmetria sferica (si supera se non simmetria)
1) Venti stellari – gas da supernovae
Si stima che ritmo produzione gas possa essere
M• ≈ 10-11 – 10-12 (Mgal/M•) in M•/anno
che per Mgal ≈ 1011 M• potrebbe essere in accordo con
M•E se MBH8 = 1
2) Stelle canibalizzate da BH (potrebbero dare origine a variabilita’
+ knots in moto proprio)
3) Gas di origine extragalattica, piccole galassie inglobate con
merger (piccole di solito sono ricche di gas)
CSO mostrano merger recente Problema: dopo merger
tempi per avere equilibrio e gas al centro possono essere lunghi
(oltre 105 anni)
Il problema maggiore nel fueling di un AGN tramite accretion
diventa quindi non un problema di energia ma di momento angolare
difficile/impossibile da misurare.
Forma assiale delle radiosorgenti (e non sferica) suggerisce che
rotazione e’ importante
Particella in orbita circolare
Momento angolare per unita’ di massa: |L|/m=(GMr)1/2
Con M = massa interna a r (M=1011 r =10kpc)
Se vogliamo accretion quindi dobbiamo perdere momento angolare
(merger tra galassie) importanza dei getti?
Che avviene attorno a BH?
Una particella in orbita attorno a BH non puo’ avere orbite stabili
entro una certa distanza; superata questa distanza minima comunque
la particella cade su BH (entro l’orizzonte)
Se BH non rotante rmin = 3Rs
Se BH rotante abbiamo rmin1 (particella ruota come BH) o
rmin2 (particella ha spin contrario)
rmin1 = Rs/2
rmin2 = 9/2Rs
BH ruotante ha alcune caratteristiche:
esiste un limite statico entro cui ogni cosa viene risucchiato e non
puo’ stare in quiete anche se esercita forze contrarie.
Il limite statico e’ raggio orizzonte in direzioni polari e maggiore
in regioni equatoriale – superficie statica ha simmetria assiale
Parametri Fisici
Campo Magnetico
Da frequenza massima di autoassorbimento:
H  2.5 10-5νmax(GHz)5Smax(Jy)-2θ(mas)4
Ma solo per compatte – di solito H da equipartizione:
Heq propto (L/V)2/7 K2/7Φ-2/7
Dove L e V sono Luminosita’ e Volume della radios.
K e’ il rapporto tra energia protoni ed elettroni (assunto spesso = 1)
Φ e’ il filling factor (1 in mancanza di meglio)
Valori tipici di Heq sono compresi tra 10-6 e 10-4 gauss
nelle regioni estese
Nelle pc scale regions possiamo avere anche qualche decimo
di gauss
La verifica della equipartizione si puo’ avere in ammassi di galassie
confrontando la pressione (energia) non termica con quella termica
ricavata dalla emissione in banda X (BT)
Energia Totale Minima (a equipartizione):
Utot propto L4/7 V3/7Φ4/7
con valori tipici 1057 – 1061 erg
Da cui posso ricavare la pressione interna
Se umin = Utot/V
Peq = (Γ – 1) umin = 1/3 umin propto (L/V)4/7 Φ
4/7
Γ = 4/3 per particelle relativistiche
Ordini di grandezze energie:
Tipo
Utot(erg)
Heq(gauss)
10-4--10-5
Tel(anni) a 5GHz
FR II hot spot
1057
104—106
FR II lobi
1058-60
10-6
107—108
FR I
1055-60
10-6
107—108
Stime vite medie
Se la separazione dei due lobi radio e’ D e si ammette che origine
e’ dal nucleo centrale, sicuramente sara’:
Trs > D/c
che con D tra 1 e 500 kpc diventa una Trs dell’ordine di 103 – 106
anni rispettivamente
Abbiamo viso pero’ che CSO hanno velocita’ dell’ordine di 0.2c
e stessa velocita’ la trovo da studio statistico separazione lobi
Da/Dr = (1 + βsep cos θ)/(1 – βsep cosθ)
Se angolo e’ casuale ricavo delle velocita’ <= 0.2c con vite medie
Cinematiche dell’ordine di 105 – 107 anni
ENSEMBLE OF ELECTRONS
N ( E)  N 0 E  
Synchrotron emissivity:
   N0 H(1 ) / 2 

 1
2
Spectral index
AGEING:
only e- with
E < E* survive
spectral break
proportional to
the source age
Original spectrum
Aged spectrum
*  H-3 t -2
Vite medie radiative
Perdite di energie radiative per effetto di emissione di sincrotrone
e IC con radiazione 3 oK provocano brusco irripidimento spettro
dell’ordine di Δα = 0.5
L’eta’ diventa: tr = 1.59 x 109 x (B1/2eq)/(Beq2 + Bci2)((1+z)γ*)1/2 yr
Bci = 3.25(1+z)2
B in microgauss e γ in GHz
Velocita’ separazione lobi da eta’ radiative vanno di solito tra 0.05
e 0.2c
Esercizio didattico su Cigno A – lavagna e quaderno
Per dettagli ad esempio Tucker: ‘radiation processes’
 FR I: Jet dominated emission, two-sided jets,
typically in clusters, weak-lined galaxies
 FR II: Lobe dominated emission, one-sided
jets, isolated or in poor groups, strong
emission lines galaxies
Radio vs optical luminosities:
LR  Lopt 1.7
(Owen & Ledlow 1994)
Ljet = 0.015 Ledd
Ledd=1.3x1038 MBH/M●
Ghisellini e Celotti AA 379 L1, 2001
Possiamo mettere in relazione la potenza radio e
l’output di energia del Jet. La potenza radio dei lobi
e’ energia accumulata da jet in vita rs
Willot et al. 1999
1) Ljet = 3 x 1021 L6/7151 erg s-1
Piu’ recentemente da cavita’ clusters: Pjet propto Pradio 0.5-0.7
vedi Cavagnolo et al. ApJ 720, 1066; 2010.
Usando la relazione di McLure e Dunlop, 2001
2) Log(MBH/M●) = -0.62 (±0.08) MR -5.41(±1.75)
Abbiamo quindi una relazione tra Ljet e MBH
la separazione tra FRI ed FRII corrisponde a un
rapporto costante Ljet/MB
E se traccio le linee Ljet = LEdd trovo che:
3) Ljet ~ 0.015 LEdd dove LEdd = 1.3 x 1038 MBH/Mo erg/s
e’ la linea che mi separa FRI da FRII
Introduciamo energia dell’ AGN usando come indicatore la
NLR nelle regioni piu’ compatte (BLR non in tutte!)
Usiamo la quantita’ di radiazione che ionizza emission line:
Fotoionizzazione da nuclear accreting radiation: Lion
Viene usato intensita’ [OII] emissione [OIII] e’ spesso
in parte oscurata
4) Lion  5 x 103 L151 (Willot et al. 1999)
 6 x 10-3 LEdd
La divisione tra FRI ed FRII corrisponde ad una separazione tra
Lion e MBH
Lion  6 x 10-3 LEDD
Quindi separazione tra FRI ed FRII e’ relazione tra Massa e
Radiazione emessa da BH
Lion/LEdd  10-3 suggerisce un valore critico di dm/dt
(accretion rate in Eddington units) in cui il modo (efficienza ?) di
accretion cambia.
Possiamo assumere che Lion  Ldisk = η dMacc/dt c2
η e’ efficienza = 0.1 e quindi
dm/dt (in Eddington units)  6x10-2 η-1 (vedi prima)
Speculazione: basso accretion vento da disco che influenza ISM
pc-kpc region e provoca rallentamento jet  FR I
Alto accretion no vento, no rallentamento  FRII
Collegamento con HEG – LEG:
E’ importante notare che esiste una forte correlazione tra
righe in emissione e l’emissione ottica nel continuo:
Optical cores (non thermal) can be directly associated to the
source of ionizing photons  jet-ionized narrow line region
A compact emission line region is present in FR I correlated
with optical non thermal
high density high covering factor: diski structure
La scarsezza di gas in low power e’ quindi importante per
differenziare le proprieta tra AGN di bassa e alta potenza.
Jet-Disk connection
see arXiv:1109.6584
90% AGN little or no jet emission
10% powerful twin jets
Vip connection between accretion (X+optical), BH (mass, spin)
jets (radio)
Dichotomy in AGN:
HEG standard cool luminous accretion disks (from X-ray) strong
Fe line + torus (cold gas). In gas-poor (no rich clusters center)
medium
LEG X-ray dominated by pc jets (non-thermal), no signature of
cold disk, no torus at all – inefficient accretion (sub-Eddington)
Accretion flows – Jet
Very high
High/soft
Low/hard
Corbel et al 2012
Accretion Power in
Astrophysics
Andrew King
Theoretical Astrophysics Group, University of Leicester, UK
accretion = release of gravitational energy from infalling matter
accreting object
matter falls in
from distance
energy released as electromagnetic
(or other) radiation
If accretor has mass M and radius R, gravitational energy release/mass is
Eacc
GM

R
this accretion yield increases with compactness M/R: for a given M
the yield is greatest for the smallest accretor radius R
e.g. for accretion on to a neutron star
( M  M sun , R  10km)
Eacc  10 erg / gm
20
compare with nuclear fusion yield (mainly H He)
Enuc  0.007c  6 10 erg / gm
2
18
Accretion on to a black hole releases significant fraction of rest—mass
energy:
R  2GM / c  Eacc  c / 2
2
2
(in reality use GR to compute binding energy/mass:
typical accretion yield is roughly 10% of rest mass)
This is the most efficient known way of using mass to get energy:
accretion on to a black hole must power the most luminous
phenomena in the universe
Lacc
Quasars:

GM 
2

M  c M
R

L  1046 erg / s
X—ray binaries:
requires
L  10 erg / s
Gamma—ray bursters:
39
L  1052 erg / s
M  1M sun / yr
10 7 M sun / yr
0.1M sun / sec
NB a gamma—ray burst is (briefly!) as bright as the rest of the universe
Accretion produces radiation: radiation makes pressure – can this
inhibit further accretion?
Radiation pressure acts on electrons; but electrons and ions (protons)
cannot separate because of Coulomb force. Radiation pressure force
on an electron is
Frad
L T

2
4cr
(in spherical symmetry).
Gravitational force on electron—proton pair is
Fgrav 
(m p  me )
GM (m p  me )
r
2
thus accretion is inhibited once
L  LEdd 
4GMm p c
T
Frad  Fgrav
, i.e. once
M
 10
erg / s
M sun
38
Eddington limit: similar if no spherical symmetry: luminosity requires
minimum mass
bright quasars must have
M  10 M sun
brightest X—ray binaries
M  10M sun
8
In practice Eddington limit can be broken by factors ~ few, at most.
Eddington implies limit on growth rate of mass: since
Lacc 4GMm p
M 2 
c
c T

we must have
M  M 0e
where
t
c T
7

 5 10 yr
4Gmp
is the Salpeter timescale
The AGN paradigm
We know (more or less) the ingredients: The AGN paradigm
Kpc scale
pc scale
Credit: A. Muller
Open issues
Jet
Characterise the
particle content,
geometry and
velocity of the
outflow/jet
Study of accretion and
ejection flows around
supermassive black holes in
AGNs
Characterise the geometry and
velocity of the outflow/wind, and its
impact on the host galaxy and
cluster
Hot corona
Credit: A. Mueller
Characterise the
geometry and mode of
the accretion flow
Accretion (inflows)
Still, we don't know exactly the accretion mode/type (SAD, ADAF, RIAF, CDAF, etc.)…
(Müller, ‘04)
Main problem: disc viscous time can be too long
As discussed before mergers and jets are important to solve this
Point
Interesting: King 2010 arXiv:1002.1808
Good review: Slexander & Hickox 2011 arXiv:1112.1949
Spectrum of a Luminous Quasar:
Jet and Disk Contributions
thermal
(disk)
synchrotron
(jet)
inverse Compton
(jet)
Lichti et al. (1994)
Synchrotron and inverse Compton Highenergy emission in blazars
The “blazar sequence”
FSRQs
BL Lacs
Fossati et al. 1998; Donato et al. 2001
Properties of Blazars
3 months,
10

the SEDs of blazars are characterized by two broad humps,
interpreted as the synchrotron and the inverse Compton
emission. Quite often the high energy hump is dominant.
Fossati et al. (1998).
The obtained SED describe a sequence with the following
properties:
i) the radio luminosity is a good tracer of the bolometric one;
ii) by increasing the radio (hence the total) luminosity, the
frequencies of the two peaks shifted to smaller values, and, at
the same time,
iii) the high energy peak became more important.
BL Lacs are dominated by the jet emission: double humped
Synchrotron + SSC spectrum
FSRQs show a clear signature of a disc + BLR
This is not a relativistic effect (jets in FSRQs high velocity!)
but an accretion effect dm/dt > 0.01 to have a disc emission.
Disc and BLR additional source of seed photons for IC
The blazar sequence was interpreted by as the result of the different amount
of radiative cooling in different sources. It is confirmed by present data.
Low power sources are BL Lac objects, with weak or absent broad emission
lines.
The main emission mechanisms are synchrotron and self Compton. Since the
cooling is limited, electrons can attain high energies, and they preferentially
produce high frequency radiation. As a result, the produced SED is “blue“
(namely, the synchrotron peak is at UV or soft X–ray frequencies, while the high
energy peak can reach the TeV band. These blazars are also called High
frequency BL Lacs, or HBL .
By increasing the total luminosty, we have objects with strong broad
emission lines, and presumably jets with stronger magnetic fields. Cooling is
more severe, and the electron energies are smaller. The peak frequencies of
the two humps shift to the “red" (sub–mm for the synchrotron, MeV for the
Compton. These are called Low frequency BL Lacs, or LBL. At the same time, the
electrons can scatter seed photons not only produced internally in the jet
(i.e., their own synchrotron photons), but also the seeds coming externally
(disk, broad line region, torus). The enhanced abundance of seed photons
makes the scattering process more important, and the high energy bump is
then dominant.
Blazar sequence confirmed by Fermi
Blazars can be divided into low power BL Lacs and high power FSRQ
This parallels FRI and FRII. This division is the results of a change
in the accretion + SMBH mass
Emitting region of most jet luminosity: still a problem (see next)
Jet power and disc luminosity correlate. Jet and accretion correlate
but jet power is larger than accretion  accretion cannot be the
only driver: e.g. accretion amplify magnetic field and this field
extract the rotational energy of the SMBH  accretion & mass
& spin
BL-Lacs
Low power BL Lacs
High Power QSS
FR I
FR II
Division a change
in accretion
regime
FSRQs
The luminosity of the BLR is a function of the γ–ray luminosity.
The first is a proxy of the disk luminosity, while the latter is a
proxy of the bolometric jet luminosity, in turn linked with the jet
power. We found that the two luminosities correlate, even
considering that the γ–ray luminosity can vary, in a single object,
by more than two orders of magnitude.
L>0.01LE
dd
Torus
~1-10 pc
G
BLR
L<0.01LEdd
SSC only
weak cooling
G
BLR <<0.2
pc
X
TeV
Core radiogalaxies
Ghisellini et al. 2009 MNRAS 396, L105;
FSRQs and BL Lacs sono nettamente separati nel piano
indice spettrale gamma e luminosita’ gamma
BL-Lac meno luminosi e + hard
La divisione potrebbe essere dovuta a un diverso accretion.
Usando Lgamma come proxy per Lbolometrica, la separazione avviene
a un accretion rate dell’ordine di 0.1 accretion rate di Eddington
Jets are carrying a large total power that correlates with the luminosity
of the accretion disk
The division of blazars in 2 classes of BLR emitting (FSRQ) and
Line-less (BL-Lacs) is a consequence of a rather drastic change of
the accretion mode:radiatively inefficient below a critical value of the
accretion rate, corresponding to a disk luminosity of about 10% of
Eddington value
La Funzione di Luminosita’ (FdL) mi dice la % di galassie che
emettono con potenza maggiore di P
Numero di oggetti per unita’ di volume con una data luminosita’ o
con luminosita’ superiore a un certo valore
Differenziata: oggetti con luminosita’ tra P e P+dP
Integrale: N (>P)
Auriemma et al. 1977 RLF bivariata:
la probabilita’ di una G di emettere in radio e’ una forte funzione
della sua Luminosita’ (massa)
Come calcolarla?
Problema campioni limitati in flusso, quindi limiti e’ un problema
per cui devo usare survival analysis…..
Radio-loud AGN
Mass variation of radio-loud fraction
fradio-loud  M*2.5
fradio-loud  MBH1.6
Vedi Best et al.: 2005 MNRAS 362, 9; 362, 25
Optical AGN
Radio-loud AGN
Mass variation of radio-loud fraction
fradio-loud  M*2.5
fradio-loud  MBH1.6
Mass-dependent radio luminosity
function
Large size of SDSS
sample of radio-loud
AGN allows the
luminosity function to
be derived as a
function of mass.
The luminosity func.
has a similar shape
(and characteristic
break luminosity) at
all masses.
Figure: the fraction of galaxies that host radio-loud AGN as a
function of both stellar mass and radio luminosity.
Mass-dependent radio luminosity
function
Repeat for black
hole masses,
using galaxy
velocity
dispersions (and
MBH-σ relation):
again, shape of
the luminosity
function is
independent of
mass.
Figure: the fraction of galaxies that host radio-loud AGN as a
function of both black hole mass and radio luminosity.
Mass-dependent radio luminosity
function
If we now take out the
mass dependence by
scaling these plots by
MBH1.6 - they line up.
 Probability of a
galaxy being radioloud depends on
mass, but the ultimate
radio luminosity of that
radio source does not
Figure: the (mass-scaled) fraction of galaxies that host radioloud AGN as a function of radio luminosity.
Key points so far
• The probability of a galaxy being radio-loud
depends strongly on its black hole mass (
MBH1.6)
• The radio luminosity of the source that results
is independent of black hole mass
• fradio-loud at highest masses is >25%. Even if all
galaxies become AGN, they must be “turnedon” for 25% of the time! => accretion rate
must be low
Interpretation summary
• Low luminosity radio sources are due to ‘dormant’
massive black holes being re-triggered by the cooling
of hot gas.
• The resulting AGN activity feeds energy to the
environment, and could be a self-regulating process.
La probabilita’ di radio loud dipende da ambiente?
Sappiamo che FR II  merger FR I  hot corona, ma dipende
Se ammasso o isolate (gruppo) ?
Localmente no, ho > rg in ammassi perche’ ho piu’ galassie ma FdL
Non cambia (attenzione cD)
Ad alto z? formazione/evoluzione? Non so pareri discordi ma
Attenzione a effetti di selezione
Probabilita’ dipende da M (Massa) ma se FRI o FRII dipende
Da Mbh + accretion!
Evoluzione QSS (e AGN in generale)
Fin da 1968 apparve chiaro che la densita’ QSS nel passato era
molto maggiore
p(z=1) = 150 р(z=0)
Assumendo evoluzione di densita’
1) Che tipo di evoluzione? Pura Luminosita’ – Pura Densita’ o altro?
Per z<3 pure luminosity evolution provides a good fit to the QSS
LF
2) Evoluzione QSS ha un picco a z = 2.5—3 e poi cala velocemente
a z>3 il numero delle QSS troppo basso per distinguere tra diversi
modelli evolutivi
Local BH MF
(Shankar et al.2009)
Local stellar MF
(Baldry et al.2008)
z=6 stellar MF
(Stark et al.2009)
z=6 BH MF
(Willott et al.2010b)
• Black hole mass function has
evolved by ~104 from z=6 to z=0
• Stellar mass function has
2
Evoluzione aspettata complessa, possibile differenza fisica ad alto
e basso z
QSS a z> 5.8 sono i sistemi piu’ massicci ad alto z
Se luminosita’ = LE  MBH > 109
Assumendo correlazione MBH con Mbulge arriviamo a Masse dell’ordine
di 1011 Masse solari
Con profonde implicazioni per cosmologia, ionizzazione della
radiazione di fondo ed altro
Vedi
Artwick & Schade ARAA 1990 28, 437
Fan et al. 2001 AJ 122, 2833 e AJ 121, 54
Netzer et al. arXiv:1308.0012 studiano la star formation e
la presenza di SMBH a z = 4.8
Selezionano sistemi con alta formazione stellare e giustificano
la presenza di un eccesso di Massa e Luminosita’ con 2 possibilita’:
1) Oggetti in fase di merger con large supply di cold gas che
produce larger BH mass and AGN Luminosity
2) Oggetti giovani dove AGN feed-back non rallenta SFR
Quasars have been detected at very large distances, corresponding
to a very young age of the Universe.
As massive as the largest SMBHs today, but when the Universe was
0.75 Gyr old!
Sesana
arXiv:1110.6445
ottima bibliografia
Bulk quasar population at z = 2-3 but quasars at z < 7
MBH in nearby quiescent galaxies  MBHs ubiquitos
MBHs correlate with bulge mass, luminosity and velocity dispersion
and probably with dark matter halo mass
Intimate connection linking SMBH mass and hosts
Starburst galaxies often associated to quasar activity
Dormant SMBHs are the relics of luminous quasars in the past
Massive galaxies results of several merging/accretion events
To-day SMBHs end product of evolutionary path
BH seeded in proto-galaxies at high z
MBH + MBH mergers and accretion = SMBHs
Galaxy mergers cold gas in the center = star formation + accretion
Energy outputs (jets – winds) feedback removing or heating gas
Self-regulating accretion
Hierarchical models ok with properties, lumin. Function ecc.
But
1) When first seed BHs?
2) Which accretion gives >109 solar masses at z = 7?
Where and when seeds of MBHs of z=7 quasars?
Cold Dark Matter Universe: DM perturbations and DM halos
Small halos collapse first and get bigger by merging with other halos
(Press and Schechter)
Baryons follow DM
In some cases Mass exceeds Jeans limit  collapse
Mj ~ 104 Mo[(1+z)/10]3/2
Baryons start to virialize in a few DM halos of 105 Mo at z ~ 50
Efficient cooling rare but possible for 106 Mo at z ~ 30 for atomic H
108 Mo at z ~ 30 for molecular H
Three main seeds of BH:
Pop III star remnants:
If m > 260Mo after ~ 2Myr star directly collapse into a BH of half
initial mass = seed!
Recent results: lower mass of PopIII stars, fragmentation and more
challenging the viability of Pop III as seed BHs
Direct collapse:
Massive seeds of ~ 105 Mo
Metal free halos and T > 104 K no H2 cooling and  gas cloud
collapses isothermally
Problems with instability rotation wind driven mass ….. Possible but
unlikely
Runaway stellar dynamics
BH of 102 – 104 Mo as end product of collisions in dense star
environment
Pop III stars form in clusters
If stellar remnants merge together we can have a 105 Mo BH
seed
preferred
------------------------------------------
Volonteri 2012 (Science)
Once we have a seed, what next?
Seed BHs need to accrete an enormous amount of gas and need to
do it fast!
See Alexander & Hickox 2012 New Astronomy Reviews
3 principal growth mechanisms:
free
1) Merger with other MBHs
2) Episodic accretion of compact objects, disrupted stars or
gas clouds
3) Prolonged continuus accretion via accretion disks
The MBH mass density in local universe is consistent with the
accreted mass by integrating quasar LF at all redshifts
The quasar mode = large amount of gas accreted in single coherent
episodes via accretion disks
A significant contribution is from obscured accretion in obscured
objects
General picture: galaxy mergers trigger inflow feeding quasar
activity
Grande Unificazione
• MBH parametro n. 1
• M• parametro n. 2
• Spin BH BH = JBH/Jmax
BH tra 0 e 1 n. 3
ricordo JBHmax = GM2BH/c
• Orientazione (Doppler boosting e oscuramento)
n. 4
Questi parametri dovrebbero descrivere ogni tipo
di AGN: grande unificazione secondo scuola di
Cambridge
Altri parametri: morfologia galassia – ambiente esterno
(ammasso o no) sembrano giocare ruolo secondario
- I primi due parametri (Massa e Accrescimento) importanti per
Luminosita’ (sono legati a LE)
- Il terzo parametro (spin) diventa importante nella formazione
o meno dei getti relativistici e quindi della attivita’ radio
(aggiornato); legato a raggio minimo quindi ad energia ed
efficienza
Schema grande unificazione
•
AGN
•
•
•
•
•
•
•
•
•
•
FSQSS
SSQSS
NLFRII
BRLRG
QSO
S1
S2
FR I
BL-Lac
QSO2
MBH
H
H
H
H
H
L
L
H
H
H
M• BH
θ
H
H
H
H
H
H
H
L
L
H
L (lungo linea di vista)
I
H
I (SSQSS vicine)
L (quasar radio quiete)
L
H
H
L
H?? (aggiunto)
H
H
H
H
L
L
L
I
I
L
SuperUnification ≡ AGN Character
•SPIN: frame dragging associated with BH spin affects
dynamics of the accretion flow
–Magnetic fields anchored in the ergosphere can tap into
the rotational energy of the hole, determining the power of
the relativistic jet - Blandford & Znajek (1977); Meier
(1999); de Villiers, Hawley, Krolik & Hirose (2005)
–increased amount of angular momentum and energy
carried outwards by the magnetic stresses compete with
what is transported in by the accreting matter, and act to
an anticorrelation between spin and accretion rate - de
Villiers, Hawley & Krolik (2003); Krolik, Hawley & Hirose
(2005)
–decoupling of accretion rate between the inner and
outer disk leads to spin-dependent build up of the inner
torus, possibly affecting the character of the X-ray
emission - Krolik, Hawley & Hirose (2005)
SuperUnification ≡ AGN Character
• Spin as a driver for the character of the radio emission (Meier 1999, see
also Bicknell 1995, Ghisellini & Celotti 2001)
ṁ=10-3, Meier 1999
Ghisellini & Celotti 2001
SuperUnification & AGN Evolution
•
•
The rate of growth of SBHs by accretion is controlled by
–
the mean radiative efficiency of accretion ε= Lacc / Ṁc2
–
the Eddington ratio η = Lacc/LEdd = ε Ṁc2 / LEdd
–
Tracing the evolution of SBHs entails following the evolution of both spin and
mass accretion rate (Gammie et al. 2004, Shapiro et al. 2005, Volonteri et al.
2005)
Obervational constraints:
–
Supermassive (109 M⨀) black holes must have been in place by a redshift
z=6.43 (t=0.87 Gyr after the big bang) (Fan et al. 2003)
–
The observed QSO + AGN luminosity density must equal the local
supermassive black hole mass density
SuperUnification & AGN
Evolution
Seed
SBH
Spin-Down from Magnetic
Dissipation of Rotational Energy
Galaxy Mergers
Gas Accretion
Obervational constraints:
Chang
9 M ) black holes must have been ineplace
in Ṁ by a redshift
Supermassive (10
⨀
Chan
Chan
z=6.43 (t=0.87 Gyr
after
the
big
bang)
(Fan et al. 2003)
ge in j
ge in
Change
The observed QSO + AGN luminosity density
must
equal
the
local
ε
in MBH
supermassive black hole mass density
?
Transition to a
Different AGN Class
Evolution of the
Luminosity Function
Eddington Ratios as driving the AGN
Activity
•McLure & Jarvis (2004)
Marchesini et al. 2004
•Radio
loud QSOs have larger SBH
masses compared to Radio quiet
QSOs, however:
•The BH mass does not appear to
correlate with Radio luminosity
•There is significant overlap between
RLQ and RQQ.
RLQ
FRI
FRII
•Marchesini, Celotti & Ferrarese (2004)
•Within
Radio Loud Objects; FRI, FRII
and RLQ are indistinguishable based
on the BH mass, but differ significantly
in mass accretion rate (or Eddington
ratio)
Mass Accretion Rate for ε =1
Da simulazioni inserendo quello che sappiamo su merger
Star formation accretion SMBH ecc ecc
Risulta che dovremmo avere una presenza di AGN radio loud
molto maggiore di quella reale
Oltre SMBH ed accretion deve esistere un altro parametro
che mi inibisce o no la radio loudness:
SPIN!
Do Black Holes Spin?
• X-ray features produced by irradiation of
relatively cold material in the vicinity of the
SBH allow to probe directly the strong field
regime and the location and kinematics of
the cold material (Reynolds & Nowak
Simulation of the profile
shape of the Fe Kα line
2003 for a review).
produced by an accretion
disk surrounding a SBH
with
varying
angular
momentum, and seen at
40 degree inclination
(Laor 1991; Fabian et al.
1989; Reynolds & Nowak
2003)
Do Black Holes Spin?
MCG-6-30-15 (Fabian et al. 2002)
XMM, 325 ks
Inner radius 2 rg
Outer radius ~6.5 rg
4C 74.26 (Ballantyne & Fabian 2005)
XMM, 28.8 ks
Inner radius 1.2 rg
Outer radius ~6 rg
Although not airtight, these observations are taken as evidence of rapidly
spinning black holes.
• MCG-6-30-15 is radio quiet, while 4C74.26 is radio loud, suggesting that
spin is not the fundamental parameter regulating radio power???.
Do Black Holes Spin?
• Timing observations could yield a signal corresponding to the period of the
last marginally stable orbit, and therefore be used to measure the BH spin
(Melia et al. 2001)
• Near IR observations of SgA*, believed to be the site of the BH at the
galactic center, detected flares with a quasi-period variations on a 17
minute timescale, pointing to a BH spin j = 0.52 (for a 3.6 106Msun BH).
Doeleman et al. 2012 Science 338, 355
M87 con 4 antenne US+ Hawaii, Arizona e California a 229 GHz
profilo di brillanza:
curve: best fit gaussiana di 40
microarcsec (-) gaussiana + ring (..)
Quindi possiamo dare un limite alla innermost stable circular
Orbit (ISCO).
Il diametro di ISCO cambia con lo spin: SPIN 0 escluso
Diametro misurato
Role of the Central Rotating Black Hole
• Important physical properties depend strongly on whether the black hole is rotating in a
retrograde or prograde fashion w.r.t. the accretion disk
• Topology of the black hole magnetosphere
• Power of the Blandford-Znajek jet that is produced
• A modified version of the Wilson & Colbert (1995) “spin paradigm” may explain a lot
of AGN spin and radio loud/quiet properties
34
Role of the Central Rotating Black Hole
1. Black holes cannot support currents or magnetic fields by themselves
•
The black hole magnetosphere is anchored in the accretion disk, supported by currents in the
inflowing plasma (BZ 1977; Punsly & Coroniti 1990)
•
Two different kinds of black hole magnetospheres
– Closed: NO open field lines on the black hole horizon
Wilms et al. (2001)
j = 0.7
Black hole-driven (Blandford-Znajek) jet
Uzdensky (2005)
– Open: significant magnetic flux is deposited on the horizon
j = –0.9
Strong black hole-driven BZ
Garofalo (2009)
Role of the Central Rotating Black Hole (cont.)
2. Shear between rotating black hole and disk likely will determine if a BZ jet will be produced
•
•
Strong differential shear will produce a magnetic tower, converting a closed magnetosphere into an open one
and producing a jet
Amount of shear between hole and disk is a strong function of black hole spin j
Uzdensky (2005)
Uzdensky & MacFadyen (2006)
Garofalo (2005)
Komissarov (2005)
jets very likely (–1 < j < 0); jets possible 0.75 < j < 0.99)
jets likely
jets UNlikely
jets very UNlikely (0 < j < 0.75; j > 0.99)
BZ Jets are most likely to form for
PROGRADE black hole spins
(relative to accretion disk rotation)
Closed magnetospheres / Jetless sources are most likely to
form for RETROGRADE black
hole spins
Role of the Central Rotating Black Hole (cont.)
3. Black hole spin also determines the amount of magnetic flux deposited on the
horizon, and therefore the POWER of the BZ jet
•
Garofalo (2009), the “gap paradigm”:
– Magnetic flux between hole and last stable orbit rapidly accretes onto horizon
– Retrograde accretion disks have much largergaps and more flux (9 GM/c2 vs. 1 GM/c2)
– So, RETROGRADE BZ jets are more powerful by 1.5 – 2 orders of magnitude
•
Combined effect of shear and magnetic flux: gross spin asymmetry
Garofalo (2009)
Role of the Central Rotating Black Hole (cont.)
4. This suggests a modified ‘spin paradigm’ for the radio loud/quiet dichotomy:
powerful FR II & FR I radio sources are produced by retrograde accretion and
radio quiet sources produced by prograde accretion
Black HoleProduced Jets
Sikora, Stawarz, &
Lasota (2007)
FR Is
BLRGs
RLQs
LINERs
SEYFERTs
PG QSRs
Accretion DiskProduced Jets
Role of the Central Rotating Black Hole (cont.)
5. Having powerful FR II and even weaker FR I radio sources produced by prograde
accretion and radio quiet sources produced by retroograde accretion SOLVES a BIG
problem for SUPERMASSIVE black holes: the 'spin paradox'
•
Radio galaxy observations had implied that SMBHs now spin slowly
•
– Powerful FR II radio galaxies (rapid spin) were much more common at z > 1
– SMBHs must now be spinning slowly (Wilson & Colbert 1995; DLM 1999)
But optical observations of AGN imply black holes now spin rapidly
– AGN appear to produce optical luminosity with efficiencies of 10 – 15 %
– This implies that SMBHs are spinning rapidly: 0.7 < j < 0.9 (Elvis et al. 2002)
• All is now consistent: SMBHs are now indeed spinning rapidly, but as prograde, radio
weak systems (DLM & Garofalo 2010)
Spin Future
•
Shadow cast by a SBH on the surrounding emitting region can probe BH spin
SIMULATIONS
j = 0.998
“VLBI” @ 0.6mm
Spin retrogrado
e possibile sua
importanza
j=0
Falke, Melia & Agol 2000
INNER JET PROPERTIES: jet launching region
To understand the mechanisms of jet formation it is crucial to
know the jet collimation structure.
Asada et al (2011) found a parabolic collimation z(r) = Kr0.58±0.02
between a few 100s Rs and 105 Rs from the core
Now we are reaching the stage to explore z(r) within ~ 100 Rs
INNER JET PROPERTIES: jet launching region
R 0.56±0.03
parabolic
Conical shape
Non spinning
Max spinning
arXiv e-print (arXiv:1411.5368)
Theoretical models for the production of relativistic jets from active galactic
nuclei predict that jet power arises from the spin and mass of the central black
hole, as well as the magnetic field near the event horizon. The physical mechanism
underlying the contribution from the magnetic field is the torque exerted on the
rotating black hole by the field amplified by the accreting material. If the
squared magnetic field is proportional to the accretion rate, then there will be a
correlation between jet power and accretion luminosity. There is evidence for such
a correlation, but inadequate knowledge of the accretion luminosity of the limited
and inhomogeneous used samples prevented a firm conclusion. Here we report an
analysis of archival observations of a sample of blazars (quasars whose jets point
towards Earth) that overcomes previous limitations. We find a clear correlation
between jet power as measured through the gamma-ray luminosity, and
accretion luminosity as measured by the broad emission lines, with the jet power
dominating over the disk luminosity, in agreement with numerical simulations.
This implies that the magnetic field threading the black hole horizon reaches
the maximum value sustainable by the accreting matter.
An inevitable consequence of Pjet∼10Prad is that the jet power is
larger than the disk luminosity. Therefore the process that
launches and accelerates jets must be extremely efficient, and
might be the most efficient way of transporting energy from the
vicinity of the black hole to infinity
It will be interesting to explore less luminous jetted sources, to get
hints on the possible dependencies of the jet power on the black
hole spin and the possible existence of a minimum spin value for the
very existence of the jet. In turn, this should shed light on the
long standing problem of the radio–loud/radio–quiet quasar
dichotomy