Accretion Cycles and Energy concepts for BHs - Landessternwarte ...

lsw.uni.heidelberg.de

Accretion Cycles and Energy concepts for BHs - Landessternwarte ...

Accretion

Cycles

and

Energy

concepts

for BHs

Max Camenzind

ZAH/Landessternwarte

Königstuhl

2007 Heidelberg

Coll: V. Gaibler, M. Krause


Outline

• Black Holes are simple – mass, angular

momentum, accretion and shear

• Black Holes have 2 different free energy

reservoirs accretion and rotation !

• Example: Microquasars X-rays very

suitable diagnostic tool on time-scales from

msecs to hours, days and years (RXTE).

• Link of jet outflows with disk evolution.

• Black Holes in gEllipticals drive Jets into the

hot cluster gas Rotational Energy !


Black Holes in Astrophysics

• Basics: M. Camenzind, Springer 2007

• Rotating Black Holes (BHs) have been

found by Roy Kerr (1963), in the same

year when Quasars have been detected.

• The metric includes off-diagonal terms

which are related to the spin of the BH.

• Major difference between non-rotating and

rapidly rotating BHs ( BZ mechanism).

BHs only have two hairs (J.A. Wheeler).


„No Hair Plane of BHs

Neutron Stars

Microquasars, Stellar BHs, M * > 30

Intermediate Mass BHs ???

Population III BHs

BHs at High Redshifts z ~ 10

RL Quasars,

Radio

Galaxies

BH s

in

Galactic

Centers

and

QSOs

Camenzind 2006


Black Holes are simple

Objects –

The environment is complex

Black Holes not only have mass,

they have angular momentum

which generates spacetime shear


Mass-Spectrum of stellar BHs

Clear Separation NS vs BHs

NS

BHs


Black Holes 2 Energy Reservoirs

• Potential energy tapped by accretion and dissipated

in UV and X-rays

• Rotational energy tapped by magnetic fields, similar

to rotating neutron stars (Blandford & Znajek 1977)

will feed energy of JETS !

L Rot

Rot = E Rot/t Rot/tbrake

brake

~ 10 46 erg/s (M H/10 /109 M S) ) (t H/t

LRot Rot = E Rot/t Rot/tbrake

brake

~ 10 38 erg/s (M H/10 /10 M S) ) (t H/t

tbrake brake = f (a, B,…) [BZ 1977]

/tbrake brake )

/tbrake brake )

LBZ BZ = k B H² ² r H²c ²c (a/M)² (Ω ( F[ΩH-ΩF]/ ]/ΩH²) ²) ~ M H


A Modern View of BZ Mechanism

OLC: Outer

Light

Surface,

compact

for Black Holes

A: Alfven

Surface

Field lines

Connecting the

ergosphere are

dragged to rot!

Plasma

injection from

near ISCO orbit;

Plasma accretion

causal: slow ms,

Alfven and fast

wwwww

Current

Sheet

Camenzind 2007

Proto-Jet

Magnetic fields

advected from

„pc-scale“


Hot

Turbulent

Disk

GRMHD Simulations

McKinney 2006


Collimation

occurs

beyond

100 GM/c²

B φ /B r =1

I-Alfvén

I-Fast / Horizon

r in

B φ /B r =1

O-Slow

I-Slow

Field Lines

O-Fast

Light “Cylinder”

O-Alfvén

v r =0 Stagnation

Null (Ω F =Ω ZAMO )

Ergosphere

Characteristic Surfaces

McKinney 2005


Each form of matter

will be driven to corotation

within the ergosphere !

Boundary Layer near Horizon ~ r H

Ω H = ω(r H )

In Schwarzschild:

No rotation

near Horizon !


Shear near

BH driven

by Spin,

not ang. mom

a = 0.5

a = 1.0

Camenzind 2007


Twisting of Magnetic Fields

• Except for induction terms, evolution of toroidal

magnetic field ~ Newtonian MHD

Source: Differential plasma rotation

Schwarzschild: no shear !

Extreme Kerr: biggest effect !

T ~ RB φ

Operates outside horizon


a = 0

a = 0 .9

Field Line Twisting by Rotating BHs

a = 0 .5

a = .998

GRMHD Simulations (Hawley et al. 2005)


30 Years Blandford-Znajek Process

Example: Wald solution (non-rotating) Testbed for Blandford-Znajek

Field lines connected to ergosphere are driven to rotation

Poynting flux Energy extraction from ergosphere !

B - E 2 2 Ω Kerr black hole in

uniform magnetic

field at infinity;

Thin plasma version.

BH magnetosphere.

a = 0.9

Ω F ~ Ω H /2 !

Force-Free GRMHD

S. Komissarov 2004


What could we Learn from

Microquasars ?

• X-ray emission from hot and cool disks is

a suitable diagnostic tool, which is not

available in optically thick sources:

(i) We can investigate spectral states

(ii) High temporal resolution (< 1 ms) of

RXTE allows for investigation of

turbulence.

(iii) New insight into link between disks

and jets.


GX339-4 lightcurve

1996 2003

X-Ray Emission:

VARIABILITY on all Time Scales

• Variations = changes in the state of the

source

• lightcurves:

GX 339-4 / GRS 1915+105

Variations on very different time scales !

“easy” observations for human time scale

GRS 1915+105

100 Mio

years in

Quasars

X (2-10 keV)

Radio (2.25 GHz)

Rau et al (2003)


Truncation paradigm

Camenzind 2007


GRO 1655-40 Spectral States

Chris Done et al. 2007


Turbulence Diagnostics in Disks

GX 399-4 Hard State vs NStar

Power ~ 1/f between low ν b and high frequency ν l

Steepens to ~ 1/f² at high frequencies ~ Keplerian

BH

Keplerian frequ near ISCO ~ 200 Hz

NS

BL

Turb

Chris Done et al. 2007


Axelsson et al. 2005

Transition from LH HS Cyg-X1

Suppression at ~ 5 Hz Evidence for moving truncation

~ 1/f Noise

5 Hz ~ viscous time time for ISCO for M ~ 10 Sun (~ 2 ms) ?


On Characteristic Frequencies

∀ ν b ~ ν visc ~ (H/R)² α ν Kep (r Trunc ) ~ 0.03 – 0.2 Hz

moves, if r Trunc decreases from ~ 20 r g to (4-6) r g .

consistent with truncation

radius moves inwards during transition.

Disk extends down to marginal stable orbit in

soft state.

Power at high frequencies stays roughly

constant modulations at truncation radius

produce fluctuations propagating inwards

through hot flow.

2 ms Kepler time at ISCO 200 ms

viscous?


Black Hole Hysteresis (X-Novae)

Belloni et al. 2005

and Jet Outflows

Rel. Blobs

Steady Jets


Linking Jets to Hot Inner Flows

• The low/hard state has a steady jet with

L R ~ L X 2/3 (Corbel 2003; Gallo 2003)

• This relation changes during transitions to

soft states: Jet line Blobby state

During rise, the faster jet catches up

the more inert slow jet formation of

knots

not seen in the transition from high/soft

to low/hard state ! SAD disk is moving

outwards.


Radio Power vs Accretion

Körding et al. 2006


Jet Correlations

Merloni et al. 2003; Falcke, Körding & Markoff 2004; Chris Done et al. 2007


The New Unifying Picture

Is this the ultimate

interpretation for

the difference

Radio-quiet vs

Radio-loud

Sources ?

Körding et al. 2006;

Chris Done et al. 2007

for Quasars


Jet Power and BH Rotation

• Radio luminosity is a poor diagnostics for

jet power.

Jet power can now be measured with

cavities produced by jets in the ambient

medium (Cyg X-1; Cyg A, gEs in clusters).

Jet activity shows a cyclic behaviour

(on time-scales of 10 – 100 Mio years).

• Jet power is easily explained in terms of

the rotational energy of central BHs.


Cyg X-1Jet-Bubble

Jet Power ~1037 erg/s

~ 100 times LRadio BH Rotational Energy ?

Gallo 2005

(60 hours WSRT)


Black Holes in gE-Galaxies

Drive Jets into Cluster Gas

Cygnus A (VLA)

3C 219 (VLA)


Cygnus A

Thermal

Chandra + VLA

330 MHz

Weak Shock

Mach ~ 1.2 – 1.4

------------ 70 kpc ---------

~ 25 Mio years old (Jet-Beam)

Beam Cocoon:

Relativistic Particles

and Magnetic Fields


MS 0735.6+7421

Chandra + VLA 330 MHz

McNamara

& Nulsen 2007

X-Ray

Cavity

~ 200 kpc

X-Ray

Cavity

~ 200 kpc


kpc

Anatomy of Jets (Cygnus A)

Beam

in fact much

more complicated

Contact

Surface

KH

unstable

Hot

Cocoon

~ 10 11 K

Bow

Shock

Cluster

Gas

Lorentz factor = 1.04, v_B = 0.28 c, Mach = 6

[ Hughes 1996 ] 6 ppb


Jet Structure depends on ambient medium

Simulated Jets in Cluster Medium: Gaibler & Camenzind 2007

Cluster Jets

Sedov-phase

Border

Line between

Sedov-phase

And cigar-phase

Protostellar

Jets

Camenzind 2005


Magnetic

Sedov-Phase

Hydro

Bow

Shock

Bow

Shock

Magnetic

vs.

Hydro η=10 -3

Morphology

similar

KH instabilities

suppressed

contact

discontinuity in

head region is

more stable.

Cocoon still not

cylindrical

M. Krause 2005


Perseus Cluster

„Remnant Cavities“

900 ks Chandra; Fabian et al. 2006


Cavity Power Mechanical Jet Power

Energy required

to generate a Cavity

= PV work + thermal

energy

H = E + PV ~ 4 PV

P cav = H / t age

Since accretion is low

Jet power explained

by Rotational

Energy, M H ~ 10 9 M S

McNamara

& Nulsen 2007


Cavity Power vs Cooling Power

Dashed lines:

Cavity power =

PV, 4PV, 16PV

All systems

above 4PV !

Radiative power

of Cluster Gas

explained by

Jet power.

Nulsen et al. 2007


Fundamental Questions

• What is the ultimate source of jet driving

(i) gravitational over disk accretion ?

(ii) spin of BH via BZ mechanism ?

(iii) both processes ? measure a !

• What is the composition of outflow ?

(i) normal disk plasma?

(ii) e+/- plasma ? clues from Hot

Spots (particle acceleration in Hot Spots;

Amato & Arons 2006) !

(iii) Poynting flux dominated jets ?


Conclusions II

Jet power in µQuasars & radio

galaxies in giant ellipticals is probably not

driven by accretion, but by rotation of BH.

Rotational energy is the ultimate jet

power in gEs and cD galaxies.

solves the heating problem of „cooling

flows“

Accretion cycles ~ 10 – 100 Mio years

( many cycles over 5 Gigayears !).

Cycles driven by refilling from kpc core

in gEs, not from the 100 kpc cluster gas.


References

• M. Camenzind: Compact Objects in Astrophysics: White

Dwarfs, Neutron Stars and Black Holes; Springer-Verlag

2007

• M. Camenzind: Cosmic BHs – from stellar to

supramassive BHs in galaxies, Ann. Physik 15, 60 (2006)

• M. Camenzind: Relativistic Outflows from Active Galactic

Nuclei, Mem. Soc. A. It. 76, 98 (2005); astro-ph/0411573

• C. Done, M. Gierlinski, A. Kubota: Modelling the behaviour

of accretion flows in X-ray binaries; astro-ph/0708.0148

• V. Gaibler, M. Camenzind, M. Krause: Large-scale

Propagation of very Light Jets in Galaxy Clusters, Proc.

Alaska Conf. on Extragalactic Jets, 2007

• McNamara & Nulsen: Heating Atmospheres with AGN,

astro-ph/0709.2152

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