Determining the Spin of Supermassive Kerr Black Holes as AGN Central Engines

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