Compact supermassive black hole binaries & recoiling black holes

1. BBHs multi-wavelength evidence new e.m. signals/ future searches recoiling BHs Probing Strong Gravity Near Black Holes, Prague, Feb. 15-18, 2010 Compact supermassive black hole binaries & recoiling black holes Stefanie Komossa, MPE Garching

2. dynamical friction regime binary hardening e.g., by stellar slingshot effects (loss-cone refilling), interact. with gas, stalling at ~1-0.1 pc?...)* emission of GWs )*[e.g., Saslaw & al. 74, Quinlan & Hernquist 97, Gould & Rix 00, Merritt 01,03, Milosavljevic & Merritt 01,03, Zier & Biermann 01, Ivanov+ 99,04, Yu 02, Blaes et al. 02, Poon & Merritt 02, Haehnelt & Kauffmann 02, Hemsendorf+ 02, Armitage & Natarajan 02,05, Escala+ 03,05, Makino & Funato 04, Berczik+ 05,06, Haardt+. 06, Dotti+ 06, Merritt 06, 07, Matsui & al. 06, Zier 07, Alexander 07, Mayer+ 07, Perets & Alexander 08, Sesana & 08, Berentzen & 08, Mayer+ 09, ....................] 1 3 evolution of SMBBHs 2 2 1 3 [Begelman, Blandford, Rees 1980]

3. BH pairs in single galaxies(NGC 6240, 0402+379, ...) two accreting BHs, spatially resolved spatially unresolvedBBH candidates - semi-periodic lightcurves (esp. OJ 287) 2ndary BH hitting disk of primary ? 2005-2007 monitoring: orbital shrinkage due to GWs ? - helically distorted radio jets (e.g. 3C345) jet-emitting 2ndary BH orbiting primary; or precession ? ( - double-peaked broad lines ? ) -post-merger candidates - X-shaped radiosourcesspin flips ?- double-double radio sourcesopen gap systems ? observational evidence for SMBBHs decreasing nuclear separation [e.g., Lehto & Valtonen 96, Silanpää 00, Merritt & Ekers 02, Komossa+ 03, Liu+ 03, Zhou+ 04, Lobanov+ 06, Rodriguez+ 07, Comerford+ 08, Valtonen+ 07-10, ... ]

4. spatially resolved systems in single galaxies: NGC 6240, 0402+379, COSMJ1000+0206, SDSSJ1254+0846 X-rays • nearby (U)LIRG z=0.024 • luminous, hard X-ray emission from two cores • accreting BHs at separation of ~ 1 kpc opt. • radio galaxy, z=0.06 • two radio cores C1,C2 • compact, variable & flat-spectrum true nuclei, at 7 pc sep. • COSMOSgal, z=0.36 • 2 cores with HST • 1.8 kpc sep. • SDSS merger, z=0.4 • two opt. quasars, unabsorberd • 21 kpc sep. (lensing unlikely) [Komossa+ 03] [Rodriguez+ 07] [Comerford+ 09, Elvis+ 09] [Green+ 10]

5. spatially unresolved can-didates: semi-periodic variability of OJ287 • semi-periodic optical variability with period ~12 yr • BBH model: burst interval = orbital period • double-peak structure: 2ndary in pre-cessing orbit impacts warped, thick disk twice • essential for finding orbital solutions: timing of all prev. peaks • orbital parameters: M1 = 1.8 1010 Msun)* M2 = 1.4 108 Msun e = 0.7, Df = 40° /orbit • „ shift“ in Sept. 2007 maximum: interpreted as orbital shrinkage due to emission of gravitational waves ( DTGW = 0.01 yr/period) )* note that the host galaxy appears to imply lower mass – Liu&Wu 02 [LV96; Nilsson et al. 06] [Valtonen+ 07] [e.g. Silanpää et al. 88, 96, Lehto &Valtonen 96, Sundelius+ 97, Pietilä+ 98, Liu & Wu 02, Valtonen+ 97,06, 07,10.....]

6. interlude:no BBHs in „broad double peakers“, so far flux • a few % of all quasars show broad double-peaked emission lines • one early idea: BBH systems; gas clouds bound to each BH • strong prediction: should see orbital motion on timescale of years • not detected • instead, processes in outer warped accretion disk around a single BH [e.g., Gaskell 83, 88, 96, Halpern & Filippenko 88, Eracleous et al. 97, Halpern & Eracleous 00, Gaskell 10]

7. interlude:no BBHs in „broad double peakers“, so far Arp 102B flux • a few % of all quasars show broad double-peaked emission lines • one early idea: BBH systems; gas clouds bound to each BH • strong prediction: should see orbital motion on timescale of years • not detected • instead, processes in outer warped accretion disk around a single BH [Gaskell 10] • SDSS1536+04[Boroson & Lauer 09] turned out to be another double-peaker; no orbital motion detected so far, v < 70 km /s /yr; [Chornock+ 09, 10] [e.g., Gaskell 83, 88, 96, Halpern & Filippenko 88, Eracleous et al. 97, Halpern & Eracleous 00, Gaskell 10]

8. extreme mass-ratio pairs: tidal disruption of white dwarfs in WD – MBH mergers X-ray lightcurve of giant-amplitude stellar tidal dis-ruption flares from inactive galaxies [e.g., Komossa & Bade 99, Halpern+ 04, Komossa+ 04, 08] EMRIs: • Lx huge: sev. 1044 erg/s • very soft X-ray spectra • from optically inactive • galaxies • factor 6000 variability • t-5/3 decline law solar-type stars: GWs only detectable from GC WDs: (partially)tidally disrupted for MBH < 105-6 Msun em & GW signalLISA rates: 0.1 – 100 /yr [e.g., Amaro-Seoane 07,Sesana+ 08; Menou+ 08] the few known events are consist. with disruption of solar-type star

9. future e.m. search for SMBBHs prior to, and quasi-simultaneous with, coalescence • wide pairs: • - radio, X-ray & optical • imaging spectroscopy • close pairs: • -Fe-line spectroscopy • and variability (IXO) • - periodic shifts in radio • position (space-VLBI) • - acceleration of precession rate • - t-dependent accretn signatures • non-active pairs: • - tidal disruption rate • (dramatically enhanced • rate, temporarily, when one • BH refills loss-cone of the • other) /accretion interrptn) • pre/post-coalescence: • - e.m. precursors or • afterglows; e.g. when • inner disk reforms • - other effects (shocks in • disk) related to recoil • - GW heating of disk • GW recoil • - off-nuclear quasars/ • emission-line shifts • - disk flares • - tidal recoil flares • - HCSS talk by Fukun Liu [e.g. Milosavljevic & Phinney 05, Armitage & Natarajan 02, Liu+ 03, Yu & Lu 02, Torres+ 04, Dotti+ 06, Koc sis+ 08, Shields+ 08, Liu & Chen 07, Tao+ 07, Hayasaki+ 08, Lippai + 08, Schnittman+ 08, Haiman+ 08, 09, Loeb 09,Palenzuela+ 09, van Meter+ 09, Megevand+ 09, Rossi+ 09, Krolik+ 09, Chen+ 09, Liu+ 09, ..........]

10. anisotropic emission of GWs from coalescing BBHs leads to recoil of the newly formed single BH recent NR simulations of BBH mergers predict BH „kicks“ with velocities up to 3800 km/s (10000 km/s);highest for m1=m2, a1=-a2=max & in orb. plane  recoiling BHs will oscillate about galaxy core, or could even leave massive ellipticals  variousastrophysical implications z recoiling supermassive black holes: kicks & superkicks [e.g., Peres 1962, Bekenstein 73, Redmount & Rees 89, ... /Baker+ 06,07,08, Brügmann+ 08, Campanelli+ 06, 07a,b, 08, Dain+08, Gonzales+ 06, 07a,b, Healy+ 08, Herrman+ 07a,b, Koppitz+ 07, Lousto & Zlochower 08, Pretorius 05, 07, Pollney+07, Schnittman+ 07, 08, Tichy & Maronetti 07, ...]

11. predicted spectroscopic signatures - kinematically off-set Broad Line Regions, ideally at v>> few 100 km/s, to distinguish from „BLR physics“ - lack of „ionization stratification“ - symmetric broad lines, (and MgII at same v as Balmer lines) Sloan Digital Sky Survey (SDSS) ideally suited; in DR7: >100.000 quasar (= major merger) spectra recoiling SMBHs – spectroscopic signatures [Komossa & Merritt 08] [Bonning+ 07]

12. SDSSJ0927+2943, @ 2650 km/s shows all predicted spectral features of a recoiling BH, plus an extra peculiar syst. of NELs [Komossa et al. 08] 2 other candidates, again based on kinematic broad line shifts, + polarimetry, recently reported, @ ~1000 km/s [Axon et al., in prep – 2009 Ringberg workshop on GN] recoiling SMBHs – search for candidates via spectroscopic signatures Komossa+ 08 • ongoing spectroscopic searches, • & ongoing predictions of other signatures of recoiling BHs in gas-rich and gas-poor systems:„disk flares“ after recoil, off-nuclear tidal-disruption flares, hypercompact stellar systems, .......

13. several lines of observational evidence for presence of supermassive binary black holes; good candidatesstill rare(one reason: detection requires one, or both, BHs to be active). predictions of quasi-simultaneous e.m. and GW signals from SMBBH mergers, and WD-MBH mergers  promising for future searches recoiling BHs: wealth of potential astrophysical implications -- depending on vkick -- still being explored, first observed candidates summary