Probing Strong Gravity Near Black Holes Prague Feb
Probing Strong Gravity Near Black Holes, Prague, Feb. 15 -18, 2010 Compact supermassive black hole binaries & recoiling black holes Stefanie Komossa, MPE Garching • BBHs • multi-wavelength evidence • new e. m. signals/ future searches • recoiling BHs
evolution of SMBBHs 2 • 1 dynamical friction regime • 2 binary hardening e. g. , by stellar slingshot effects (loss-cone refilling), interact. with gas, stalling at ~1 -0. 1 pc ? . . . )* 1 3 [Begelman, Blandford, Rees 1980] • 3 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, . . ]
observational evidence for SMBBHs - BH pairs in single galaxies (NGC 6240, 0402+379, . . . ) two accreting BHs, spatially resolved - spatially unresolved BBH candidates - semi-periodic lightcurves (esp. OJ 287) 2 ndary BH hitting disk of primary ? 2005 -2007 monitoring: orbital shrinkage due to GWs ? - helically distorted radio jets (e. g. 3 C 345) jet-emitting 2 ndary BH orbiting primary; or precession ? ( - double-peaked broad lines ? ) - post-merger candidates - X-shaped radio sources spin flips ? - double-double radio sources open gap systems ? [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, . . . ] decreasing nuclear separation
spatially resolved systems in single galaxies: NGC 6240, 0402+379, COSMJ 1000+0206, SDSSJ 1254+0846 X-rays opt. • nearby (U)LIRG • radio galaxy, • COSMOS gal, z=0. 024 z=0. 06 z=0. 36 • luminous, hard X- • two radio cores ray emission from • 2 cores with C 1, C 2 two cores HST • c ompact, variable & • accreting BHs at • 1. 8 kpc separation of ~ 1 flat-spectrum kpc true nuclei, at 7 pc sep. [Komossa+ 03] [Rodriguez+ 07] [Comerford+ 09, Elvis+ 09] • SDSS merger, z=0. 4 • two opt. quasars, unabsorberd • 21 kpc sep. (lensing unlikely) [Green+ 10]
spatially unresolved candidates: semi-periodic variability of OJ 287 • semi-periodic optical variability with period ~12 yr • BBH model: burst interval = orbital period • double-peak structure: 2 ndary in pre-cessing orbit impacts warped, thick disk twice • essential for finding orbital solutions: timing of all prev. peaks • orbital parameters: M 1 = 1. 8 1010 Msun )* M 2 = 1. 4 108 Msun e = 0. 7, Df = 40° /orbit )* note that the host galaxy appears to imply lower mass – Liu&Wu 02 • „ shift“ in Sept. 2007 maximum: interpreted as orbital shrinkage due to emission of gravitational waves ( DTGW = 0. 01 yr/period) [e. g. Silanpää et al. 88, 96, Lehto &Valtonen 96, Sundelius+ 97, Pietilä+ 98, Liu & Wu 02, Valtonen+ 97, 06, 07, 10. . . ] [LV 96; Nilsson et al. 06] [Valtonen+ 07]
• 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 flux interlude: no BBHs in „broad double peakers“, so far [e. g. , Gaskell 83, 88, 96, Halpern & Filippenko 88, Eracleous et al. 97, Halpern & Eracleous 00, Gaskell 10]
[e. g. , Gaskell 83, 88, 96, Halpern & Filippenko 88, Eracleous et al. 97, Halpern & Eracleous 00, Gaskell 10] Arp 102 B [Gaskell 10] • 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 flux interlude: no BBHs in „broad double peakers“, so far • SDSS 1536+04 [Boroson & Lauer 09] turned out to be another doublepeaker; no orbital motion detected so far, v < 70 km /s /yr; [Chornock+ 09, 10]
[e. g. , Komossa & Bade 99, Halpern+ 04, Komossa+ 04, 08] extreme mass-ratio pairs: tidal disruption of white dwarfs in WD – MBH mergers X-ray lightcurve of giant-amplitude stellar tidal disruption flares from inactive galaxies • factor 6000 variability • t-5/3 decline law the few known events are consist. with disruption of solar-type star EMRIs: solar-type stars: GWs only detectable from GC WDs: (partially) tidally disrupted for MBH < 105 -6 Msun em & GW signal LISA rates: 0. 1 – 100 /yr [e. g. , Amaro-Seoane 07, Sesana+ 08; Menou+ 08] • Lx huge: sev. 1044 erg/s • very soft X-ray spectra • from optically inactive galaxies
future e. m. search for SMBBHs prior to, and quasisimultaneous 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: talk by Fukun Liu - 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 [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, . . ]
recoiling supermassive black holes: kicks & superkicks • 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 m 1=m 2, a 1=-a 2=max & in orb. plane • recoiling BHs will oscillate about galaxy core, or could even leave massive ellipticals various astrophysical implications z [e. g. , Peres 1962, Bekenstein 73, Redmount & Rees 89, . . . / Baker+ 06, 07, 08, Brügmann+ 08, Campanelli+ 06, 07 a, b, 08, Dain+08, Gonzales+ 06, 07 a, b, Healy+ 08, Herrman+ 07 a, b, Koppitz+ 07, Lousto & Zlochower 08, Pretorius 05, 07, Pollney+07, Schnittman+ 07, 08, Tichy & Maronetti 07, . . . ]
recoiling SMBHs – spectroscopic signatures • 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 Mg. II at same v as Balmer lines) • Sloan Digital Sky Survey (SDSS) ideally suited; in DR 7: >100. 000 quasar (= major merger) spectra [Bonning+ 07] [Komossa & Merritt 08]
recoiling SMBHs – search for candidates via spectroscopic signatures • SDSSJ 0927+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] 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 tidaldisruption flares, hypercompact stellar systems, . . . .
summary • several lines of observational evidence for presence of supermassive binary black holes; good candidates still 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
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