‘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). E GW ~ 10 58 ergs (M T /10 6 M sun ) in ~ 500 (M T /10 6 M sun ) secs • • L GW ~ 10 23 L sun • Asymmetric scenarios give rise to kicks, these can be as large as 3-5 10 3 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 ~ 10 53 ergs ( M T /10 6 M sun ) >> 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 f 2/3 /d L ; f ,t ~ [(1+z) � ] 5/3 f 11/3 • h ~ [(1+z) � ] /d L ; f ,t ~ [(1+z) � ] f f • However: • localization to ~ square degrees [Holz-Hughes] • distance obtained is redshift dependent (arcmin 2 << deg 2 ) (from Kocsis et.al. 2006,2008 and Holz1Hughes 05)
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 f 2/3 /d L ; f ,t ~ [(1+z) � ] 5/3 f 11/3 • h ~ [(1+z) � ] /d L ; f ,t ~ [(1+z) � ] f 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! (d l vs z)
Nature cooperates… • Super massive binary black holes seem to exist NGC 6240. Black hole pair In the process of merging? • Understand both gravitational and electromagnetic wave • Understand both gravitational and electromagnetic wave emissions from key systems – Binary black holes interacting with surrounding media 10 51 Ergs routinely inferred� (~10 49 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…
������������������������������������ �observations indicate the presence of supermassive BHs in the center of 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; O’Neil et. al; Megevand et.al; Corrales et.al, etc. ] – Pre/merger events from gas/plasmas in between BHs / torques on disk [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 How does the curvature/dynamics influence EM fields? • Blandford-Znajek. Connected to “Penrose” process for Kerr bh’s surrounded by magnetic fields (anchored by the disk) • Stray charges accelerate � photons � pair production • 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 ▼ a T ab =0 � ▼ a T ab (fluid) = �▼ a T ab (em) = �F ab J a if ρ,P << B 2 then ▼ a T ab (fluid) << F ab J a ≈ 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 Far load: to dissipate energy 1 1 1 1 1 1 L ~ B 2 a 2 + + +
• • 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 ~ B 2 a 2 in the aligned • we knew. L ~ B 2 a 2 in the aligned case [Tchechovskoy,Narayan,McKinney 2010]. • For misaligned case? • Poynting flux still there, along B • L ~ B 2 a 2 (1 + cos 2 ) (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 ~ V 2 /R • Thus, L ~ B 2 v 2 (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 v 2 ) 10 43 ergs [M 8 B 4 ] 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 10 4 G, 10 8 M O flux ~ 10 43-44 ergs. IF Poynting flux energy efficiently transferred to observable emissions, interesting pre/post merger • observations 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 ~ 10 16-17 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!
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