Orbital Dynamics of Eccentric Compact Binaries

Transcription

1 Orbital Dynamics of Eccentric Compact Binaries Laboratoire Univers et Théories Observatoire de Paris / CNRS Collaborators: S. Akcay, L. Barack, N. Sago, N. Warburton Phys. Rev. D (2015), arxiv: [gr-qc] Phys. Rev. D submitted (2015), arxiv: [gr-qc]

2 Outline ➀ Gravitational wave source modelling ➁ Averaged redshift for eccentric orbits ➂ First law of mechanics and applications

3 Outline ➀ Gravitational wave source modelling ➁ Averaged redshift for eccentric orbits ➂ First law of mechanics and applications

4 Source modelling for compact binaries log 10 (r /m) 4 1 (compactness) post Newtonian theory numerical relativity perturbation theory & self force mass ratio 4 log 10 (m 2 /m 1 )

5 Source modelling for compact binaries log 10 (r /m) q m 1 m m 2 1 (compactness) post Newtonian theory numerical relativity perturbation theory & self force m mass ratio 4 log 10 (m 2 /m 1 )

6 Source modelling for compact binaries m 2 log 10 (r /m) r m 1 v 2 c 2 Gm c 2 r (compactness) post Newtonian theory numerical relativity perturbation theory & self force mass ratio 4 log 10 (m 2 /m 1 )

7 Source modelling for compact binaries log 10 (r /m) 4 m 2 1 (compactness) post Newtonian theory numerical relativity perturbation theory & self force m mass ratio 4 log 10 (m 2 /m 1 )

8 Source modelling for compact binaries log 10 (r /m) m 2 EOB 4 m 1 m = m 1 + m 2 1 (compactness) post Newtonian theory numerical relativity perturbation theory & self force mass ratio 4 log 10 (m 2 /m 1 )

9 Comparing the predictions from these methods Why? ˆ Independent checks of long and complicated calculations ˆ Identify domains of validity of approximation schemes ˆ Extract information inaccessible to other methods ˆ Develop a universal model for compact binaries

10 Comparing the predictions from these methods Why? ˆ Independent checks of long and complicated calculations ˆ Identify domains of validity of approximation schemes ˆ Extract information inaccessible to other methods ˆ Develop a universal model for compact binaries How? Use the same coordinate system in all calculations Using coordinate-invariant relationships

11 Comparing the predictions from these methods Why? ˆ Independent checks of long and complicated calculations ˆ Identify domains of validity of approximation schemes ˆ Extract information inaccessible to other methods ˆ Develop a universal model for compact binaries How? Use the same coordinate system in all calculations Using coordinate-invariant relationships What? ˆ Gravitational waveforms at future null infinity ˆ Conservative effects on the orbital dynamics

12 Comparing the predictions from these methods Paper Year Methods Observable Orbit Spin Detweiler 2008 SF/PN redshift observable Blanchet et al SF/PN redshift observable Damour 2010 SF/EOB ISCO frequency Mroué et al NR/PN periastron advance Barack et al SF/EOB periastron advance Favata 2011 SF/PN/EOB ISCO frequency Le Tiec et al NR/SF/PN/EOB periastron advance Damour et al NR/EOB binding energy Le Tiec et al NR/SF/PN/EOB binding energy Akcay et al SF/EOB redshift observable Hinderer et al NR/EOB periastron advance Le Tiec et al NR/SF/PN periastron advance Damour et al NR/PN/EOB scattering angle hyperbolic } Bini, Damour Shah et al SF/PN redshift observable Blanchet et al } Dolan et al SF/PN precession angle Bini, Damour Isoyama et al SF/PN/EOB ISCO frequency Akcay et al SF/PN averaged redshift eccentric

13 Comparing the predictions from these methods Paper Year Methods Observable Orbit Spin Detweiler 2008 SF/PN redshift observable Blanchet et al SF/PN redshift observable Damour 2010 SF/EOB ISCO frequency Mroué et al NR/PN periastron advance Barack et al SF/EOB periastron advance Favata 2011 SF/PN/EOB ISCO frequency Le Tiec et al NR/SF/PN/EOB periastron advance Damour et al NR/EOB binding energy Le Tiec et al NR/SF/PN/EOB binding energy Akcay et al SF/EOB redshift observable Hinderer et al NR/EOB periastron advance Le Tiec et al NR/SF/PN periastron advance Damour et al NR/PN/EOB scattering angle hyperbolic } Bini, Damour Shah et al SF/PN redshift observable Blanchet et al } Dolan et al SF/PN precession angle Bini, Damour Isoyama et al SF/PN/EOB ISCO frequency Akcay et al SF/PN averaged redshift eccentric

14 Outline ➀ Gravitational wave source modelling ➁ Averaged redshift for eccentric orbits ➂ First law of mechanics and applications

15 Post-Newtonian expansions and black hole perturbations m 2 log 10 (r /m) r 4 m 1 1 (compactness) post Newtonian theory numerical relativity post Newtonian theory & self force perturbation theory & self force mass ratio 4 log 10 (m 2 /m 1 )

16 Averaged redshift for eccentric orbits ˆ Generic eccentric orbit parameterized by the two invariant frequencies t = 0 = 0 t = P = T n = 2π P, ω = Φ P m 1 ˆ Time average of z = dτ/dt over one radial period [Barack & Sago 2010] m 2 P z 1 P 0 z(t) dt = T P ˆ Coordinate-invariant relation z (n, ω) is well defined in GSF and PN frameworks

17 Averaged redshift vs semi-latus rectum e = 0.1 1/z GSF p [Akcay et al. 2015]

18 Averaged redshift vs semi-latus rectum e = 0.2 1/z GSF p [Akcay et al. 2015]

19 Averaged redshift vs semi-latus rectum e = 0.3 1/z GSF p [Akcay et al. 2015]

20 Averaged redshift vs semi-latus rectum e = 0.4 1/z GSF p [Akcay et al. 2015]

21 1PN Extracting post-newtonian coefficients Coeff. Exact value Fitted value Fitted value [Akcay et al. 2015] [Akcay et al. 2015] [Meent, Shah 2015] e (8) 4 ± e (1) 2 ± e ±

22 1PN 2PN Extracting post-newtonian coefficients Coeff. Exact value Fitted value Fitted value [Akcay et al. 2015] [Akcay et al. 2015] [Meent, Shah 2015] e (8) 4 ± e (1) 2 ± e ± e (2) 7 ± e 4 1/4 1/4 ± e 6 5/2 5/2 ±

23 1PN 2PN 3PN Extracting post-newtonian coefficients Coeff. Exact value Fitted value Fitted value [Akcay et al. 2015] [Akcay et al. 2015] [Meent, Shah 2015] e (8) 4 ± e (1) 2 ± e ± e (2) 7 ± e 4 1/4 1/4 ± e 6 5/2 5/2 ± e (4) (5) e (7) e (3)

24 1PN 2PN 3PN Extracting post-newtonian coefficients Coeff. Exact value Fitted value Fitted value [Akcay et al. 2015] [Akcay et al. 2015] [Meent, Shah 2015] e (8) 4 ± e (1) 2 ± e ± e (2) 7 ± e 4 1/4 1/4 ± e 6 5/2 5/2 ± e (4) (5) e (7) e (3) New coefficients at 4PN and 5PN orders [van de Meent, Shah 2015]

25 Outline ➀ Gravitational wave source modelling ➁ Averaged redshift for eccentric orbits ➂ First law of mechanics and applications

26 First law of binary mechanics ˆ Canonical ADM Hamiltonian H of two point masses m a ˆ Variation δh + Hamilton s equation + orbital averaging: δm = ω δl + n δr + a z a δm a ˆ First integral associated with the variational first law: M = 2 (ωl + nr) + a z a m a ˆ These relations are satisfied up to at least 3PN order

27 Applications of the first law ˆ Conservative dynamics beyond the geodesic approximation ˆ Shift of the Schwarzschild separatrix and singular curve ˆ Calibration of EOB potentials for generic bound orbits M = z ω z m 1 ω n z n L = z m 1 ω R = z m 1 n

28 Applications of the first law ˆ Conservative dynamics beyond the geodesic approximation ˆ Shift of the Schwarzschild separatrix and singular curve ˆ Calibration of EOB potentials for generic bound orbits M = z ω z m 1 ω n z n L = z m 1 ω R = z m 1 n

29 Schwarzschild singular curve separatrix n const. sing. curve m 2 ω [Warburton et al. 2013]

30 Schwarzschild singular curve n separatrix n const. sing. curve m 2 ω [Warburton et al. 2013]

31 Shift of the Schwarzschild singular curve ˆ Singular curve ω = ω sing (n) characterized by condition (n, ω) (M, L) = 0 ˆ In the test-particle limit q 0 this is equivalent to [ ( 2 nω z ) ] n z ω z 2 = 0 ˆ O(q) shift in ω = ω sing (n) controlled by z GSF (n, ω)

32 EOB dynamics beyond circular motion H real m 2 m 1 EOB m 1 + m 2 H (A,D,Q) eff ˆ Conservative EOB dynamics determined by potentials A = 1 2u + ν a(u) + O(ν 2 ) D = 1 + ν d(u) + O(ν 2 ) Q = ν q(u) p 4 r + O(ν 2 ) ˆ Functions a(u), d(u) and q(u) controlled by z GSF (n, ω)

33 Summary ˆ GSF/PN comparison for eccentric orbits relying on z (n, ω) ˆ First law of mechanics for eccentric-orbit compact binaries ˆ Numerous applications of the first law: Conservative dynamics beyond the geodesic approximation Shift of the Schwarzschild separatrix and singular curve Calibration of EOB potentials for generic bound orbits... Prospects ˆ GSF/PN comparison for eccentric orbits relying on ψ (n, ω) ˆ Extension of the first law to precessing spinning binaries

34 Additional Material

35 Redshift invariant for circular orbits ˆ It measures the redshift of light emitted from the point particle [Detweiler 2008] x E obs E em = (pa u a ) obs (p a u a ) em = z m 2 m 1 ˆ It is a constant of the motion associated with the helical Killing field k a : t particle observer z = k a u a u a obs dt p a E obs ˆ In coordinates adapted to the symmetry: z = dτ dt = 1 u t u a em dτ p a E em x

36 Schwarzschild separatrix IBSO [Barack & Sago 2010]

37 Schwarzschild separatrix IBSO n = 0 ω [Barack & Sago 2010]

38 Shift of the Schwarzschild separatrix ˆ Separatrix ω = ω sep (e) characterized by the condition n = 0 ˆ GSF-induced shift of Schwarzschild ISCO frequency [Barack & Sago 2009; Le Tiec et al. 2012; Akcay et al. 2012] ω isco ω isco = (4) q ˆ GSF-induced shift of Schwarzschild IBSO frequency? ˆ O(q) shift in ω = ω sep (e) controlled by z GSF (n, ω)