Determining the Spin of Determining the Spin of Supermassive Kerr Black Holes Supermassive Kerr Black Holes
as AGN Central Enginesas AGN Central Engines
Herman J. Mosquera Cuesta Herman J. Mosquera Cuesta (ICRANet/Italy - ICRA/Brazil) (ICRANet/Italy - ICRA/Brazil)
Anderson Caproni (UNICSUL/Brazil) Anderson Caproni (UNICSUL/Brazil) Zulema Abraham (IAG-USP/Brazil)Zulema Abraham (IAG-USP/Brazil)
Kerr BH + Particle
Precession
• Rotating BH drags the spacetime around it (Lense – Thirring 1918)Lense – Thirring 1918).
• Particle in an orbit with an axis non-parallel to the spin of the BH will experience torques
• The orbit will precess
Bardeen – Petterson (1975)Bardeen – Petterson (1975)
Kerr BH + Disk
Alignment
+ Viscosity
Howcan it be observed?
From the shape of the accretion diskFrom the shape of the accretion disk
Warped diskRBP
Howcan it be observed?
From the From the Precession of Precession of pc scale jetspc scale jets
Radio Jet (pc)
Warped diskRBP
Right Ascension (02h 40m)
Dec
linat
ion
(-00
o 1
3')
07s.007s.4
30"
35"
Right Ascension Offset (arcsec)
0.8
0.4
0.2
0.0
-0.2
-0.4
0.4 0.2 0.0
C
S1
S2
NE
06s.6
Howcan it be observed?
From the From the structure structure of the of the radiogalaxy radiogalaxy in kpc scales in kpc scales
Radio Jet (pc)
Large scale Radio Structure (kpc)
Warped diskRBP
Jet precession in pc scalesJet precession in pc scales
How do we observe them
1 pc 1 mas
VLBI: Very Long Baseline Interferometry
1.4 GHz
VLBI
3C279
superluminal velocities
1992
1994
1996
1998
20 40 60 80light years
3C273
Jetsare
wiggled
Velocity of each component is constantVelocity is different for the different componentsPosition angle in the plane of the sky of each component is different
Angle with the lineof sight is different
We find a sistematic effect in βobs vs. η, sugesting precession precessão
x η
φΩ
y
observerjet
η
φΩ
y
(Abraham & Romero (1999)
plane of the sky
line of sight
φβφββ
cos1
sinapp −
= = 3.9o φ0 = 10o η0 = -120 γ= 10.8φβφββ
cos1
sinapp −
= = 3.9o φ0 = 10o η0 = -120 γ= 10.8
γ=1
√1−β2
3
5
7
9
11
13
1960 1965 1970 1975 1980 1985 1990 1995 2000
Time
βobs C2
C4
C5
C6
C7
C8C9
C3C10
-170
-150
-130
-110
-90
-70
-50
1960 1965 1970 1975 1980 1985 1990 1995 2000
Time
η (d
eg)
C2
C3
C4
C5
C6
C7 C8
C9
C10
P = 16 years
Precession of QSO Jets at kpc ScalesPrecession of QSO Jets at kpc Scales
Precession model using the Bardeen-Peterson effect
(Caproni, Mosquera Cuesta & Abraham, 2004, ApJ, 616, L99)
BH
spin (a*)
log (RBP/Rms)
Locus of Pprec/MBH = constant
3C345
3C273
3C279
OJ287
3C120
Precession from a BH binary system (Abraham & Romero 1999)
BH
spin (a*)
log (RBP/Rms)
Locus of Pprec/MBH = Constant
3C345
3C273
3C279
OJ287
3C120
Shape of the accretion diskShape of the accretion disk
Rigid body
Warped disk
RBP
Keplerian outer disk
RBP is too small to be measured with current ang. resolution !!
NGC 1068
Optical image(1.1 m Hall telescope)
7 × 6 arc min
30 arc sec
HST
1 kpc
HST VLAWilson & Ulvestad 1987
NGC 1068: Seyfert 2 Gallimore et al.(2004)
VLBA 1.4 GHz
core
counter jet
100 pc2 pc
VLBA 5 GHz
masers H2O
free-freecontinnum
Lodato & Bertin, A&A 398, 517 (2003)
Initial jet direction MBN = (0.8 – 1.2) × 107 MMd = (8.6 – 9.4) × 106 M
Σ0 = (1.1 – 1.5) × 106 g cm-2
Σd (ξ )=Σ0 ξs
s = 1
Rex = 1 pc
How long does it taketo get aligned?
What is the value of RBP
Alignment Time should be smaller than Lifetime of the AGN and
Jet Phases ~ (1-2)*10^5 years
Τ align = < 1.5 × 105 Y
1 kpc
NGC 1068 in kpcscales: Wilson & Ulvestad (1987)
υjet=0 .17c
Jet was formed 104 years ago
(derived from the movement of the components close to the core)
dJ BN
dt=−2πsinϕ∫ΩLT Ld (r )rdr
ϕ( t )=ϕ0e(t−t 0 )/T ali
Pprec (t )=P0 e( t−t 0)/Tali
Sheuer & Feiler (1996)
P0 T≃ alin
The way to infer the KBH Radius: Combining info from: RBP vs. a* and Talign vs. a*
The End