The Role of Binary-Binary Interactions in Inducing Eccentric Black Hole Mergers

The Role of Binary-Binary Interactions in Inducing Eccentric Black Hole Mergers - CIERA / Northwestern University with Johan Samsing (Princeton), Carl Rodriguez (MIT), Carl-Johan Haster (CITA), & Enrico Ramirez-Ruiz (UCSC) Work initiated at the Kavli Summer Program in Astrophysics 2017 Niels Bohr Institute

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form?

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? ~ BBH =[M 1,M 2, ~ S 1, ~ S 2, ~ extrinsic ]

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? ~ BBH =[M 1,M 2, ~ S 1, ~ S 2, ~ extrinsic ] Spin magnitude models Posteriors eff eff + p( eff ) eff

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? ~ BBH =[M 1,M 2, ~ S 1, ~ S 2, ~ extrinsic ] Spin magnitude models Posteriors eff eff + p( eff ) eff = Odds ratio Farr, W. et al. 2017 (Nature 548, 7662)

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? ~ BBH =[M 1,M 2, ~ S 1, ~ S 2, ~ extrinsic ] Spin magnitude models Posteriors eff eff + p( eff ) eff = Data rules out highly spinning, aligned systems Odds ratio Farr, W. et al. 2017 (Nature 548, 7662)

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? + ef f = : Branching Ratio p( NObservations ef f Posteriors ~ ~ ~ ~ BBH = [M1, M2,S1, S2, extrinsic ] ef f ) Spin magnitude models ef f Data rules out highly spinning, aligned systems (Ncluster /Nf ield ) MZ et al. 2017 (ApJ 846, 82) Odds ratio Farr, W. et al. 2017 (Nature 548, 7662)

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? + ef f NObservations = : Branching Ratio p( ef f Posteriors NObservations SN Kick Prescriptions ~ ~ ~ ~ BBH = [M1, M2,S1, S2, extrinsic ] ef f ) Spin magnitude models ef f Data rules out highly spinning, aligned systems (Ncluster /Nf ield ) MZ et al. 2017 (ApJ 846, 82) Odds ratio Farr, W. et al. 2017 (Nature 548, 7662)

DISENTANGLING FORMATION SCENARIOS Where and how did LIGO s black holes form? ef f NObservations : Branching Ratio (Ncluster /Nf ield ) MZ et al. 2017 (ApJ 846, 82) + Masses may help, but can take ~100 detections = Odds ratio p( ef f Posteriors NObservations SN Kick Prescriptions ~ ~ ~ ~ BBH = [M1, M2,S1, S2, extrinsic ] ef f ) Spin magnitude models ef f Data rules out highly spinning, aligned systems Farr, W. et al. 2017 (Nature 548, 7662)

CAN ECCENTRICITY CONTRIBUTE?

CAN ECCENTRICITY CONTRIBUTE? e a 19/12 t GW (1 e 2 0) 7/2

POST-NEWTONIAN DYNAMICS Samsing et al. 2017 (PRD 97, 103014) Resonant encounters can facilitate highly relativistic close encounters

POST-NEWTONIAN DYNAMICS Samsing et al. 2017 (PRD 97, 103014) Resonant encounters can facilitate highly relativistic close encounters where dissipation Samsing & Ramirez-Ruiz 2017 (ApJ 840, L14) of orbital energy from GW emission can result in rapid, highly-eccentric black hole mergers

POST-NEWTONIAN DYNAMICS What role do binary-binary encounters play?

POST-NEWTONIAN DYNAMICS What role do binary-binary encounters play? see e.g. Hut & Bahcall 1983, Fregeau et al. 2004, Antognini & Thompson 2015 for background

POST-NEWTONIAN DYNAMICS periapse precession orbital decay (GWs)

ENDSTATE PROBABILITIES MZ et al. 2018 (in prep)

ENDSTATE PROBABILITIES E ij < 0; a ij < 10(R s,i +R s,j ) MZ et al. 2018 (in prep)

ENDSTATE PROBABILITIES cross sections X = b 2 max N X N tot b max = 4 v crit +3 a max v 1 (c.f. Hut & Bahcall 1983, Samsing et al. 2014, Antognini & Thompson 2015) MZ et al. 2018 (in prep)

BINARY-BINARY CONTRIBUTION Binary-single and binary-binary scatterings from realistic cluster models Perform O(10 5 ) scatterings of binarysingle and binary-binary encounters from various CMC models: Rvirial = [1, 2] kpc Z = [0.25, 0.05, 0.025] Z M = [2e5, 5e5, 1e6, 2e6] M

BINARY-BINARY CONTRIBUTION Binary-single and binary-binary scatterings from realistic cluster models Perform O(10 5 ) scatterings of binarysingle and binary-binary encounters from various CMC models: Rvirial = [1, 2] kpc Z = [0.25, 0.05, 0.025] Z M = [2e5, 5e5, 1e6, 2e6] M Analyze the efficiency of binarybinary BH encounters relative to binary-single BH encounters at inducing inspiral efficiency inspiral during interaction MZ et al. 2018 (in prep)

BINARY-BINARY CONTRIBUTION Binary-single and binary-binary scatterings from realistic cluster models Perform O(10 5 ) scatterings of binarysingle and binary-binary encounters from various CMC models: Rvirial = [1, 2] kpc Z = [0.25, 0.05, 0.025] Z M = [2e5, 5e5, 1e6, 2e6] M Analyze the efficiency of binarybinary BH encounters relative to inspiral efficiency binary-bianry binary-single binary-single BH encounters at inducing inspiral during interaction MZ et al. 2018 (in prep)

BINARY-BINARY CONTRIBUTION Binary-single and binary-binary scatterings from realistic cluster models Perform O(10 5 ) scatterings of binarysingle and binary-binary encounters from various CMC models: Rvirial = [1, 2] kpc Z = [0.25, 0.05, 0.025] Z M = [2e5, 5e5, 1e6, 2e6] M Analyze the efficiency of binarybinary BH encounters relative to inspiral efficiency binary-bianry binary-single binary-single BH encounters at inducing inspiral during interaction MZ et al. 2018 (in prep) Though rarer occurrences, binary-binary interactions contribute ~20-40% of eccentric in-cluster mergers

ECCENTRICITY OF MERGERS Inspirals induced during resonant interaction maintain appreciable eccentricities in the LIGO band Inspiraling binaries can form in band with eccentricities near e=1 10 Hz MZ et al. 2018 (in prep)

ECCENTRICITY OF MERGERS Inspirals induced during resonant interaction maintain appreciable eccentricities in the LIGO band Inspiraling binaries can form in band with eccentricities near e=1 10 Hz Post-encounter binaries that are ejected from cluster or merge before another encounter have eccentricities too low for LIGO to measure MZ et al. 2018 (in prep)

ECCENTRICITY OF MERGERS Inspirals induced during resonant interaction maintain appreciable eccentricities in the LIGO band Inspiraling binaries can form in band with eccentricities near e=1 10 Hz Post-encounter binaries that are ejected from cluster or merge before another encounter have 10-2 Hz eccentricities too low for LIGO to measure but they may be measurable by LISA! see e.g. Breivik et al. 2016 (ApJ 830, L18), Samsing & D Orazio 2018 (arxiv) MZ et al. 2018 (in prep)

CONCLUDING REMARKS Including of post-newtonian dynamics in strong encounters of black hole systems can lead to rapid and highly-eccentric black hole mergers Binary-binary interactions significantly contribute to eccentric GW inspirals, leading to ~20-40% of inspirals induced by resonant interactions binary-bianry Inspirals during binary-binary resonant encounters have eccentricities measurable by LIGO, while tight binaries formed from these encounters have binary-single eccentricities accessible by LISA