Manuela Campanelli Rochester Ins4tute of Technology. Tes4ng GR with Numerical Studies of Black Hole Binaries

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1 Manuela Campanelli Rochester Ins4tute of Technology Tes4ng GR with Numerical Studies of Black Hole Binaries Sackler 2012 Conference Ins2tute for Theory and Computa2on, Center for Astrophysics Harvard University May 14-17, 2012

2 Massive Binary Black- Hole Mergers MBHs are observed at the centers of all galaxies with bulges (Gueltekin++2009, etc) Hierarchical build- up of galaxies from smaller structures è galaxies merger è BBH mergers [Mayer ] Torques from gas, stellar dynamical fric4on, gravita4onal slingshot bring the pair to sub- pc scales Then, GW emission (3-10% of the total mass) drive the binary to the final merger. The BH remnant will recoil from its host structure, depending on the BH spins and masses at merger. Merger/Post- Merger could also be observable in EM spectrum, provided that enough gas is present.

3 In order to study BHs and gravita4onal radia4on we need to evolve the GR Equa4ons numerically. Today s challenges General Rela4vis4c Numerical Calcula4ons There has been an ongoing effort since the 60 s to do this Only in the last 7 years has it actually been possible to evolve mul4ple black hole space4mes [Pretorius, 2005; Baker++2006; Campanelli++,2006, Scheel++,2007]. Long accurate waveforms to match early PN inspiral for a variety of BH mass ra4o, spins, eccentricity. Kicks, BBH with magne4zed mayer Development of more efficient, reliable (open- source), GR- MHD codes (einsteintoolkit.org)

4 BH binaries span over a large parameter space: Gravita4onal Waveforms L S 1 S 2 Waveforms encode informa4on about the BH parameters (mass, spins), distance, merger rates, etc, and are essen4al on assis4ng GW detectors to predict what to expect and for physical informa4on extrac4on NINJA I: BBH waveforms used to test of all data analysis algorithms [AyloY , Cadona ] NINJA 2: BBH analysis in real data in close collabora4on with LSC/Virgo. NRAR: NR groups span BBH parameter space. hyps:// project.org/

5 Hybrid Gravita4onal Waveforms Matching of PN and NR waveforms (1:10 BBH waveform for the NR/AR Collabora4on) 2 x x h(t) 0 2 h sqrt(f) [1/sqrt(Hz)] x BHB with mass ra4o 1: [Nakano ] -2 x Time [s] 10 Frequency [Hz] The gravita4onal wave strain in the 4me domain (Lej) and the effec4ve gravita4onal wave amplitude in the frequency domain (Right) for 1 : 10 BBH with the total mass, 500M. The binary is op4mally oriented and placed at 100Mpc of a gravita4onal wave detector.

6 Extreme mass- ra4o BBH 1:100 mass ra4o BBH, with 16 levels of refinements in AMR [Lousto & Zlochower, 2011]

7 Spins Dynamics and Gravita4onal Radia4on Recoils The recoil is generated by the asymmetric beaming of gravita4onal radia4on at merger, due to spin- orbit coupling (and/or unequal masses) Recoils up to 4,000 km/s (superkicks) for in- plane BH spins [Campanelli++2007, 2007b, Gonzalez++2007] Recoil depends sinusoidally on the ini4al phase of the binary, and linearly (at leading order) on the spin magnitude: bobbing of the orbit

8 When spins are aligned with L, repulsive spin- orbit coupling delays the merger (orbital- hangup effect), maximizing the amplitude of gravita4onal radia4on (up to 10%) [Campanelli ]. New Calcula4ons of GW Recoils Combined with the superkick effect (which maximizes the asymmetry of momentum radiated), this leads to very large recoils [Lousto & Zlochower, 2011]. peak occurs at 5000 km/s in the case of nearly aligned spins α=0.91 (Nonlinear) α=0.707 (Nonlinear) α=1 (Nonlinear) α=0.707 (Linear) Par4al alignment of the spins by gas accre4on cannot inhibit large recoils as conjectured in [Bogdanovic et al (2007), Doo et al. (2010)] Hangup kick probability distribu4on shijed to higher recoil veloci4es 3000 V New kick formula with higher order spin terms θ/π

9 Consequences the Recoils Probabili4es that remnant BH recoils in any direc4on from host structure (from SPH simula4ons of hot and cold accre4on models) [Lousto++2012]: 0.02% for galaxies with v esc ~ 2500 km/s 5% for galaxies with v esc ~1000 km/s 20% for galaxies with v esc ~500 km/s Consequences for growth of SMBHs in galaxies and IMBH forma4on in globular clusters

10 Hangup Kick Movie Hangup Kick (Lej) and Radiated Power (Right) [Lousto & Zlochower, PRL (2011)], visualiza4on by H.P. Bischof]

11 EM Signals from BBH Inspirals and Mergers? Poten4al for GW- EM astronomy: - Standard Sirens: distance vs redshij measurements[schutz 1986, Holz & Hughes 2005] - Understanding of BH dynamics, merger scenarios, highly rela4vis4c plasma, jet forma4on, etc Need accurate theore4cal calcula4ons to weed through high- cadence all- sky survey astronomy data (e.g. Pan- STARRS, LSST) and differen4ate them from single AGNs Challenges: - Size of the problem (scales ranges from 10 5 pc to 10-5 pc) - Realis4c, accurate GRMHD codes Do systema4c studies of each stage of the coalescence, bridging the gaps among the stages a 1000M a 20M a 10M Shi+12 Noble+12 Giacomazzo+12 In the last stages, the binary BBH gravity is modeled via: - Newtonian theory: t merger >> t inflow (a 1000s M) - Post- Newtonian theory: t inflow t merger (a M) - Full Strong field GR: t merger << t inflow (a < 10M)

12 Newtonian simula4ons: Brief Summary of Results Gap forms at r 2a due to the torque exerted by the binary [MacFadyen & Milosavljevic 2008, Cuadra et al, 2009]. Surface density s4ll builds up at r=2a and gap s4ll exists, though mayer accretes faster through the gap's edge (due to MHD stresses) [Shi ]. GR simula4ons: Large Lorentz factors from collisions of test- par4cles [Van Meter ]. Interes4ng Dynamics of EM fields (double Jets) [Palenzuela ; Palenzuela ]. Streams near BHs in hot gas clouds [Bode ; Farris ], and circumbinary disks [Farris , Giacomazzo++2012] Shi+12 Need longer orbital dynamics because the amount of gas available to be heated in a merger depends on the balance between internal MHD stresses (and MRI), that drive inflow, and BBH torques, that tend to keep gas away from the merging black holes.

13 Circumbinary MHD Accre4on into Inspiraling BBHs Noble, Mundim, Nakano, Krolik, MC, Zlochower, Yunes, arxiv: v1 Radia4vely Efficient Geometrically Thin Accre4on Disk - Cool to constant entropy, H/r=0.1, r=[3,10]a 0 - Poloidal Magne4c Field following density contours - GRMHD code: Harm3D [Noble++,2009] Evolve 3.5 PN equa4on of mo4on evolu4on for 127 orbits - Ini4al Study M1=M2, BHs not in the grid - RunIN: keep binary at fixed separa4on (a 0 = 20M) un4l t = 40,000M, and then inspiral down to 8M. - RunSS: keep binary at fixed separa4on (a 0 = 20M) un4l t = 75,000M

14 Inspiral (RunIN) Quasi Steady- State (RunSS) Surface Brightness (Log 10 ) Surface Density (Linear) Movies by ScoY Noble (adpated by HP. Bischof): hyp://ccrg.rit.edu/~scn/cmhdaiibh/

15 Luminosity Luminosity is characteris4c of AGN with excess at edge of gap due to dissipated binary torque work, though small surface density within the gap leads to luminosity deficit there Excess from dissipa2on of binary Torque work (Thomson op4cal depth) Noble++, arxiv: v1

16 The Lump and its Variability Lump- BH streams Modula4on The luminosity is modulated at a frequency (ω peak ) that is a beat between the orbital frequency of the disk s surface density maximum (the lump) and the binary orbital frequency. If the disk is op4cally thick, the periodic modula4on may be suppressed. Ray- tracing will help to determine the quality of the signal Noble++, arxiv: v1

17 Summary and Conclusions BBH mergers are excellent laboratories for tes4ng strong- field GR. NR calcula4ons have already made some amazing predic4ons: BBH mergers radiate up to 10% of total mass (depending spin) è ideal sources for any GW detector (adligo, pulsar 4ming and future space GW observatories). If spins are aligned with L then there is a delay in the merger (hang- up orbits) BBH merger remnants can recoil at up to km/s ( km/s for hyperbolic encounters) è recoils candidates GR is scale invariant, so these results are independent of the total mass... The power and recoil from a 10 9 M binary is the same as 1M binary. There could be enhanced, dis4nguishable, light signatures due to MHD accre4on in strong dynamical GR (characteris4c variability, jet produc4on, etc). Collaborators: Krolik (JHU), Lousto (RIT), Mundim (RIT), Nakano (RIT), Noble (RIT), Yunes (Montana), Zlochower (RIT), einsteintoolkit.org, Ninja and NRAR collabora4ons. Acknowledgements: NSF (PHY , PHY , PHY , PHY , OCI , PHY , PHY , AST ), NASA ATPF (07- ATFP , 08- ATFP )