Observational Signatures of Merging Black Holes (in galactic nuclei)

Transcription

1 Observational Signatures of Merging Black Holes (in galactic nuclei) E. Sterl Phinney Caltech

2 Dynamical masses of nuclear BH van den Bosch Entire galaxy!

3 Phases of Black Hole merger Log(Time to Merger) log(separation)

4 Phases of Black Hole merger (108Msun, q=0.5) Dynamical friction in Galaxy's potential Log(Time to Merger) a>10pc, t > 106y log(separation)

5 Phases of Black Hole merger (108Msun, q=0.5) Dynamical friction in Galaxy's potential Log(Time to Merger) BH dominate mass within orbit, eject stars a>10pc, t > 106y 0.1<a<10pc, Several orbits a~t-1 log(separation)

6 Phases of Black Hole merger (108Msun, q=0.5) Dynamical friction in Galaxy's potential Log(Time to Merger) a>10pc, t > 106y BH dominate mass Within orbit, eject stars Ejection of Stars from large r (non-axisym) and/or Gas torques 0.1<a<10pc, Several orbits a~t-1 t~ y log(separation)

7 Phases of Black Hole merger (108Msun, q=0.5) a>10pc, t > 106y Dynamical friction in Galaxy's potential Log(Time to Merger) BH dominate mass Within orbit, eject stars Ejection of Stars from large r (non-axisym) and/or Gas torques Gravittional radiationdriven, f>1 nhz, coupled Circumbinary disk w/ gap 0.1<a<10pc, Several orbits a~t-1 t~ y 0.01<a<0.03pc t~ y log(separation)

8 Phases of Black Hole merger (108Msun, q=0.5) Dynamical friction in Galaxy's potential Log(Time to Merger) a>10pc, t > 106y BH dominate mass Within orbit, eject stars Ejection of Stars from large r (non-axisym) and/or Gas torques Gravittional radiationdriven, f>1 nhz, coupled Circumbinary disk w/ gap Gravitaitonal radiation Driven, f>25nhz, decoupled from Circumbinary disk, pushing fossil inner disk log(separation) 0.1<a<10pc, Several orbits a~t-1 t~ y 0.01<a<0.03pc t~ y 0.005<a<0.01pc t~106y, P~2y

9 Phases of Black Hole merger (108Msun, q=0.5) Log(Time to Merger) Strong-field gravity, bobbing, zipping horizons, GW recoil log(separation) t~1 y P<3d

10 Log(Time since Merger) Post-merger Evolution Black Hole(108Msun, q=0.5) Recoil kick ~q: Oscillation in galaxy Potential; AGN with Bound disk. Viscous fill-in of Hole in circumbinary disk. log(separation) t >107 y t~ y

11 Grand survey of merger signatures C-radio jets Enhanced tidal disruption Precessing Z-radio jets & Interupted Tidal disruption Funny SEDs Phinney additions to Schnittman

12 Theorist We've given you dozens of clear, unambiguous ways to identify merging BH at all pre and post-merger phases. What's the problem with you slowpokes? Why do you keep announcing discoveries, then shooting them down?

13 Theorist We've given you dozens of clear, unambiguous ways to identify merging BH at all pre and post-merger phases. What's the problem with you slowpokes? And why do you keep announcing discoveries, then shooting them down? Observer (laughing uncontrollably) Clear? Unambiguous? Have you looked at all the weird spectral and photometric variability of galactic nuclei? And anyway, you guys keep contradicting each other!

14 a h=g / 4 2 q=m/m Inside BH horizon Smaller q Binary binding energy= intial stellar cusp binding 20pc 1pc 0.08pc r i =GM / 2 BH potential Dominates stars 300pc 10pc 0.9pc Orbital periods ~ ,000 y eccentric

15 7.3pc M~108Msun, Porb ~ 105 y. a~5ah , Rodriguez et al Astro-ph/ See also Burke-Spolaor Only 1:3114

16 A new way to find BBH entering the final parsec (in the stellar ejection phase) Stars are not point masses for <10 8Msun BH: Tidal disruption Rate enhanced by X1000 during Stellar ejection phase Wegg&Bode ArXiv: (see also Ivanov Chen+ 2009, But those not Self-consistent, overoptimistic)

17 1/7 yrs!

18 Tidal Captures not primarily in Kozai wedge. Most are just complicated 3-body orbits.

19 10-50% of all tidal disruptions in the Universe should be from this binary phase. So if monitor galaxies with known tidal disruptions for a decade, those that repeat will, with 99% probability, be BBHs in the Stellar ejection phase!

20 Other ways to identify BBH stellar ejection phase C-symmetry FR I (slow, entrained -cf De Young) jets Hypervelocity stars (but can also be from binary stars+ single BH) (Fossil) core cuspless stellar distributions

21 The final parsec problem Yu 2002 Loss cone 1010yr increasin g Gravitational radiation 10-5pc Dynamica l friction decreasing a 10kpc Begelman, Blandford & Rees 1980

22 Getting through the final parsec Stellar ejection finishes after binary hardens Spherical core: loss cone emptied. Slow refilling by 2body relaxation Enhanced relaxation due to massive bodies (GMCs etc) -Peretz & Alexander 2008 Triaxiality: from merger-induced bar: no loss cone -centrophilic orbits (Berentzen arxiv: ; Khan+ arxiv: ; Merritt talk) Gas migration (needs Mgas> Mbh)

23 Problem? Triaxial?: no problem Axisymmetric: problem tmerg>10gyr Kahn+ arxiv tmerg<1gyr Yu 2002 Loss cone 1010yr Note: orbit doesn't circularize increasin g Gravitational radiation 10-5pc Dynamica l friction decreasing a 10kpc

24 Gas-driven migration? Depends on circumbinary gas mass, radial distribution (i.e. past binary history), 1D vs 3D gaps/orbits, disk thermal equlib (thickness), star Formation due to self-gravitating instability at high disk mass... Doesn't solve: Does solve Lodato Chang Armitage & Natarajan 2002, 2005 Cuadra Kocsis+ arxiv

25 Looking for post-final parsec sources Ways to find Binaries In GW stage

26 Offset/doubled emission lines Boroson & Lauer cf similar systems Gaskell 1986 Cf Loeb , Shen+Loeb 2010: Not double -dispersion too high! arxiv: SDSS J red: broad+narrow lines blue: broad only some abs at intermediate vel. dv=3500km/s Porb=100y Msun

27 (Geodetic) spin precession Tprec=107y Tprec=103y

28 S-shaped radio sources? S-shaped radio Sources: BH spin precession due to geodetic precession In BBH binary? Begelman, Blandford & Rees Core VLBI systems Tprec~ ,000y But could be disk precession also. (cf SS433, Roos 1988) 6 5/ 2 P prec,i =6 10 a/0.1pc 1/2 8 M 8 mi 10 M sun /m1 m 2 y

29 Manifestations during the GWdominated phase of inspiral

30 Funny AGN spectra from circumbinary disk gaps before merger Milosavljevic & Phinney 2005 Lodato Gultekin+Miller Tanaka E8Msun, at decoupling r=1000m, h/r=0.01, w/h=0,10, Beware of silicate 2000Angstrom dust features!

31 How complete is the gap? Do the BH accrete from the circumbinary disk Noble : 3D MHD disk, gap open, but accretion only halved D'Orazio D alpha disk: accretion reduced by 5, q>0.05, accretion modulated: compare analytic: Kocsis ; Lodato

32 Periodic Accretion from Gap Noble : 3D MHD disk, gap open, but accretion only halved D'Orazio D alpha disk: accretion reduced by 5, q>0.05, accretion modulated Hasayaki misaligned circumbinary disk: circular 2 bursts per orbit (plane crossing), 1 per orbit if eccentric. Note: orbital period at disk decoupling (viscous time = gw time) is ~ 3M8 y. So interesting only for low-mass holes

33 Gravitational Waves: in PSR timing band Pulsar Timing LISA

34 Gravitational wave detector sensitivity Predicted amplitude 2006 pulsar timing Parkes Dominated by massive Msun BH. PPTA 2012 LIGO 2007 S5 run enhanced LIGO 2009 LISA Pathfinder 2011 LISA 2018? LISA 2018 Advanced LIGO 2014

35 Burst from fossil disk driven in during decoupled phase Chang et al L~ t(to merger)-5/4. But Hayasaki can become radiatively inefficient Fossil disk may not exist due to gas escape on horseshoe orbits: Baruteau

36 Final jet produced by compression of fossil disk Giacomazzo MHD: B frozen in disk amplifed by binary torque compression, so L(jet) increased by 104. (earlier force-free have no flux freezing, so no amplification of B).

37 Response of decoupled circumbinray disk to GW mass loss+kick Penna & Phinney 2006, Krolik , Bode PhD 2011, Bode+Phinney 2012, Rosotti Gravitational radiation removes mass-energy: circular orbits become eccentric, all in phase initially. Dominates inner disk Kick also makes orbits eccentric (parabolic far enough out), but with initial phase m=1 varying.

38 Disk response diagnostic of disk thickness and vertical structure Bode PhD 2011 Bode+Phinney 2012

39 Post-merger fill-in of disk Milosavljevic & Phinney 2005 Shapiro Liu+Shapiro Farris Takamitsu could be 100 all sky sources brightening 10%/yr in soft X

40 Long after the merger If q~0.5, rapidly spinning Bhs with spins not aligned with orbital angular momentum, can get kicks of 1000's of km/s -cf Lousto For small <0.1, spins a/m<0.5, or aligned, only <100's of km/s. Ejected BH carries inner accretion disk and stars -enough disk to power for Myr. Non-nuclear quasars, offset BLRs... cf. Komossa review. Change in loss cone can initially enhance, then reduce tidal disruption rate: Stone&Loeb , Li Blecha When recoiling black hole out of nucleus, enhances nuclear star formation.

41 X-shaped radio sources -merger-induced BH spin change?ekers & Merritt 2002 X-type radio sources: Spin, hence disk reorientation After BBH merger? But see Saripalli & Subrahmanyan 2009: Wing correlation with galaxy minor axis suggests wings are just redirected jet backflow in most cases.

42 Grand survey of merger signatures X Radio lobes C-radio jets Enhanced tidal disruption Precessing Z-radio jets & Interupted Tidal disruption Funny SEDs Modified after Schnittman