Higher powered jets from black hole space-times L. Lehner (Uof - - PowerPoint PPT Presentation

‘Higher powered’ “jets” from black hole space-times

• L. Lehner

(Uof Guelph/Perimeter Inst/CIFAR) (Uof Guelph/Perimeter Inst/CIFAR)

• C. Palenzuela, L. Liebling
• C. Hanna, D. Neilsen, E. Hirschman, M. Anderson

Gravitational Waves: ‘Current’ detectors…

• 2

(?) Future detector: LISA.

Ideal source: Binary black holes…

[Pretorius 05, ..]

(some) notable outcomes…

• Radiation: convert ~ 5% of total intial mass and angular
• momentum. (can be higher for ‘tuned’ collisions).
• EGW ~ 1058 ergs (MT/106 Msun) in ~ 500 (MT/106 Msun) secs
• LGW ~ 1023Lsun
• Asymmetric scenarios give rise to kicks, these can be as

large as 3-5 103 km/s! (claim Quasar SDSS J092712.65+294344.0 )

– Yet… these need some tweaking. – Yet… these need some tweaking. – A few 100s km/s more typical. (Mech Energy~ 1053 ergs (MT/106 Msun) >>

SN !)

• Dynamics/energetics of thesystem can profoundly

influence neighboring matter/gas/plasma, etc.

Example of ‘what’s coming’: LISA signals?

LISA: superb signal to noise ratio. Excellent accuracy to: strain & freqn

• waves will be ``seen’’ directly and to

very large redshifts (z~ 5-15 …)

• h ~ [(1+z) ]5/3 f2/3/dL ; f,t ~ [(1+z) ]5/3 f11/3
• h ~ [(1+z) ]

f /dL ; f,t ~ [(1+z) ] f

• However:
• localization to ~ square

degrees [Holz-Hughes]

• distance obtained is

redshift dependent

(from Kocsis et.al. 2006,2008 and Holz1Hughes 05)

(arcmin2 << deg2)

LISA signals?

LISA: superb signal to noise ratio. Excellent accuracy to: strain & freqn

• waves will be ``seen’’ directly and to

very large redshifts (z~ 5-15 …)

• h ~ [(1+z) ]5/3 f2/3/dL ; f,t ~ [(1+z) ]5/3 f11/3
• h ~ [(1+z) ]

f /dL ; f,t ~ [(1+z) ] f

• However:
• localization to ~ square degrees [Holz-Hughes]
• distance obtained is redshift dependent

An electromagnetic counterpart resolves these issues Can get a purely gravitational & clean Hubble diagram! (dl vs z)

Nature cooperates…

• Super massive binary black holes seem to exist
• Understand both gravitational and electromagnetic wave

NGC 6240. Black hole pair In the process of merging?

• Understand both gravitational and electromagnetic wave

emissions from key systems

– Binary black holes interacting with surrounding media 1051 Ergs routinely inferred (~1049 LHCs) ?! The ‘key’ is to tell observers what to look for

Studying relevant systems

• Deal with spacetime curvature

– Einstein equations. That’s the ‘solved’ part! (ie… if you ‘think’ about it.. NR can likely give the answer, for comparable masses that is….)

• Black holes… are not really quite in vacuum…must deal

with fields describing gas and electromagnetic fields with fields describing gas and electromagnetic fields

– Poorly understood systems [we don’t control the experiment] – Emission process? – What physics?

• Electromagnetic fields?
• Matter, what matter ?

Concentrate on appropriate systems…

• bservations indicate the presence of supermassive BHs in the center
• f galaxies, surrounded by gas and an accretion disk

these galaxies have undergone mergers binary black hole merger further, AGNs BHs are surrounded by a disc of matter likely magnetized.

Two fronts.

(circumbinary picture)

• Pre/prompt/post - merger emissions?

– (pre/prompt) Binary black holes as stirrers of ‘stuff’ – (post) merged black hole as bully for matter

Binary black holes and emissions

• Different possible options.

– Postmerger events from circumbinary disks around BHs

[Milosavljevic-Phinney; Lipai-Loeb; Lipai et.al, Bonning et.al; Bode et.al; O’Neil et. al;

– Pre/merger events from gas/plasmas in between BHs / torques on disk

O’Neil et. al; Megevand et.al; Corrales et.al, etc.] [Armitage et.al; MacFadyen et.al.; Dotti et.al;

• Chang. et.al.;

Palenzuela et.al.; Bode et.al…]

Binary black holes as blenders. A new spin on an old story

• Blandford-Znajek. Connected to “Penrose” process for

Kerr bh’s surrounded by magnetic fields (anchored by the disk)

• Stray charges accelerate photons pair production

How does the curvature/dynamics influence EM fields?

• Stray charges accelerate photons pair production
• cascade. BH becomes surrounded by a tenuous

conducting plasma with little inertia

[Goldreich-Julian, Blandford-Znajek]

Approach: Force-free electrodynamics

▼aTab=0 ▼aTab(fluid) = ▼aTab(em) = FabJa if ρ,P << B2 then ▼aTab(fluid) << FabJa ≈ 0 · = 0 , q + x = 0 → E3B = 0 System can thus be studied in an ``effective way”

• plasma supplies charges/currents

which in turn enforce E.B = 0

• furthermore, fields can carry charged

particles, and establish a circuit Need to solve this problem, what can we expect that is interesting/relevant?

Basic picture from the membrane paradigm

BH: (poor) conductor Battery: Black hole’s rotation Plasma to close the circuit

1 1 1 1 1 1 + + +

Far load: to dissipate energy L ~ B2 a2

• IF

IF analogy can be pushed further, there is little special about BH’s rotation, any relative motion of conductor wrt ambient magnetic field would give and EMF

• SMBH merger will give such scenarios

– Prior to merger, 2 bhs orbital motion inside the circumbinary disk region – After merger finally BH rotates, but also might have a velocity due to recoil

• Can this intuition be confirmed? And connection further exploited?
• we knew. L ~ B2 a2 in the aligned
• we knew. L ~ B2 a2 in the aligned

case [Tchechovskoy,Narayan,McKinney

2010].

• For misaligned case?
• Poynting flux still there,

along B

• L ~ B2 a2 (1 + cos2)

(can be predicted using Damour 74 + mp!)

[Palenzuela,Garret,LL,Liebling, PRD 2010]

What if it moves?

• E.g. after black holes merge, individual black holes

prior to merger.

• Where from? From membrane paradigm bh is a
• Where from? From membrane paradigm bh is a
• conductor. If moving through a B field, induce E ~ v x B

EMF=V ~ (vB) ; L ~ V2/R

• Thus, L ~ B2v2 (from boost)

Onto the binary case

• Orbit Black holes move through B. Hall effect analogue!
• As in head1on case, ‘circuit’ can be established due to charge separation
• Thus, expect Poynting flux through orbiting stages. Also at late time (BZ).

[Palenzuela,LL,Liebling , Science 2010]

F

Poynting flux

Putting all together: L ~ ( 1 [a/0.6]2 + 100 v2) 1043 ergs [M8 B4]2 * EM flux acts as a “spacetime tracer” * Can exploit ‘standard’ BBH results to predict much of the EM flux behavior Multimessenger? : LISA & PTA for gravity waves

• EM observations? For 104G, 108MO flux ~

1043-44 ergs. IF Poynting flux energy efficiently transferred to observable emissions, interesting pre/post merger

• bservations possible; to z=1 ?

What/how to see it? This story just beginning… How about Ligo/Virgo sources?

Wrapping up: ‘back’ to stellar masses

• NS source magnetic fields and issues

– Talks at HEPRO!

– Pulsar spin down (Spitkovsky) – Magnetosphere interactions ? (Lyutikov-Hansen) – NS crust-quakes (Tsang) – QPOs and magnetars (Cerda-Duran et al)

• Gravity stirrers + above

– NS-BH interaction. (BH moves in field of NS) [McWilliams-Levin, our

collaboration]

– NS collapse (both freqn, and, field grows. If star is byproduct of NS-NS merger, starting field ~ 1016-17 G!, independent test of BH-NS vs NS-NS for sGRB) [our collaboration] – NS-NS close interaction..

In progress: In progress:

• How does the BH gets bold?
• Energetics?
• Angular structure.
• ev vs. ff
• Emission processes. sGRB precursor?
• Connection with BNS merger / after merger
• Different magnetic field structure of star

Hanna,LL,Liebling,Palenzuela, Thompson,Neilsen, Hirschmann…

Summary

• Gravitational wave astronomy ‘around the corner’.

Multimessenger astronomy requires identifying electromagnetic/neutrino counterparts

• GWs (and even more with counterparts) possibly will tie many

knots, inform models, etc.

• Still much to be understood, the field is just beginning to

consider options and possibilities. In particular, we need to follow your lead!