Relativistic loss-cone dynamics: Implications for the Galactic Center

Transcription

1 Relativistic loss-cone dynamics: Implications for the Galactic Center Relativistic loss-cone dynamics: Implications for the Galactic Center Tal Alexander Weizmann Institute of cience 3 RR < NR Plunge log a/mpc 2 RR > NR MBH LO GW timescales GW eparatrix agw RR>NR contour AI contour MW -stars GW -. log j - Bar-Or & TA 2 -.

2 Getting stars to the MBH The stellar dynamical loss-cone problem: How do stars in a galactic nucleus interact strongly with a massive black hole (MBH) and/or fall into it, and at what rates? catterers Test star "Loss cone" BH and "strong interaction zone" Implications Plunge processes: Tidal disruption ares,2, tidal detonation 3, tidal scattering 4, gravitational wave (GW) ares Inspiral processes: GW extreme mass ratio inspirals (EMRIs),2,, tidal squeezars 6, accretion disk capture Exotic stellar populations near MBHs 7,8,9 MBH+stars formation and evolution,,2,3 How do galactic nuclei randomize and relax? :TA & Hopman 23 2:Bar-Or & TA 2 3: TA 2 4:TA & Livio 2 :Hopman & TA 2, 26a, 26b 6:TA & Morris 23 7:TA 999 8:TA & Livio 24 9:Perets, Hopman & TA 27 :TA & Hopman 29 :TA & Kumar 2 2:Bar-Or & TA 24 3:Bregman & TA 22

3 Getting stars to the MBH Randomization by relaxation Relaxation near a MBH Non-coherent relaxation (NR: E, ) Resonant relaxation (RR: ) Pointpoint interactions Orbit-orbit interactions Perturbing stars Effect on perturbed star Rauch & Tremaine 996 catterers Test star tationary ellipses in point mass potential calar resonant relaxation "Loss cone" BH and "strong interaction zone" Planar rosettes in spherical potential Vector resonant relaxation T NR [ P /N ]/ log Q Q = M /M T RR [ P/N ]P/tcoh / log Q: relaxation boost from close encounters P/t coh : relaxation boost from long coherence Near MBH: T RR /T NR log Q(P/t coh ) Fast evolution to : trong interaction with the MBH

4 Getting stars to the MBH Randomization by relaxation The classical (pre-rr) loss-cone: Plunge vs inspiral Loss primarily by by -relaxation: T j 2 T E j = / c (E) log a log a long P Plunge E, scattering log acrit long P scattering Plunge Inspiral scattering Dissipation short P log a isco log lc / c log /c short P Detectable GW log a isco log lc / c log /c (Lightman & hapiro 977; Cohn & Kulsrud 978) (TA & Hopman 23; Hopman & TA 2) Γ plunge N (< r h )/ log(c/ lc )T E Γ inspiral N [< rcrit(t E )] / log(c/ lc )T E Γ inspiral O(.)Γ plunge

5 log (d 2 n/dlgj dlga) -. < -. < < -.. < -.. <. -3. <. -3. < -3.. < -3.. <. -. <. -. < -. <-. LO GW inspiral plunge Relativistic loss-cone dynamics: Implications for the Galactic Center Getting stars to the MBH Randomization by relaxation The danger of unquenched RR: No inner cusp (No GR stars, no GW EMRIs, no... ) (Bar-Or & TA 2) The fortunate coincidence conjecture: (Hopman & TA 26) Unquenched, RR drives all stars to plunge orbits (no EMRIs!). log (a/mpc) R p = 8.e /yr R i =.e+ /yr n snap = n p =469 n i = -. O(β 2 j 2 ) GR in-plane chwarzschild precession becomes signicant before O(β /2 j 7 Q ) GW dissipation log (j) GR precession quenches RR and allows EMRIs to proceed unperturbed, decoupled from the background stars. log (a/mpc) 2 Last table Orbit RR > NR log (/c)

6 Relativistic loss-cone dynamics: Implications for the Galactic Center The relativistic loss-cone The η -formalism tellar dynamics in the presence of correlated noise (Ben Bar-Or's talk) 3 RR < NR Plunge log a/mpc 2 RR > NR MBH LO GW timescales GW eparatrix agw RR>NR contour AI contour MW -stars Adiabatic invariance(?) quenches RR at low-j NR dominates evolution on long time scales Dynamical modeling of the relativistic loss-cone E ective RR di usion that express correlated noise and secular precessions, together with NR di usion and GW dissipation, provide a powerful scalable Monte Carlo tool for modeling long-term dynamics and loss-rates of galactic nuclei in the realistic N? limit( ).? Correct form and interpretation of the chwarzschild Barrier (Merritt, TA, Mikkola & Will 2). GW -. log j (Bar-Or & TA 2) - -. Validated against N -body results in the low-n? regime.

7 GW EMRI and tidal disruption rates in steady state 3 log (d 2 n/dlgj dlga) -. < < < < -.. <. log (a/mpc).. R p = 7.4e /yr -3. <. -3. < -3. <-3. LO GW AI contour DC contour inspiral plunge max a/a -. R i = 2.2e /yr - n snap = n p =962 n i = log (j) R p(nr+rr) / R p(nr) 2 Rate [/yr] Plunges 3 4 Inspirals 6 MC data without RR MC data with RR M /M Galactic nucleus model (MWEG) GR+mass precession GW+NR+RR mooth noise+mass quenching Adiabatic invariance saves EMRIs: Fortunate coincidence validated.

8 Relativistic loss-cone dynamics: Implications for the Galactic Center Puzzles of the Galactic center: Origin of the -stars? Where's the old stellar cusp? Efficient scattering by massive perturbers (Perets, Hopman & TA 27) Incoming scattered binary Ejected Hyper Velocity tar Captured star (Hills 99) 3 RR < NR.8 RR > NR CDF[P(>jobs)] log a/mpc 2 MBH - LO Tidal disruption RR>NR contour AI contour MW -stars (observed) Binary capture model ji Disk origin model ji -3 cluster Warped disk(s) [Dark cluster?] [Binaries?]. -. log j.4 Cusp TBC PK=.4 ±..2 Cusp Disk PK=. ±. Core TBC PK=6e-9 ± e-7 Core Disk PK=e-3 ± e ~. pc ~.4 pc P(>jobs).8 ~. pc absovich, Bar-Or & TA 26, in prep. [Disrupted cluster + IMBH?] Molecular clumps Blue giants B dwarfs Red giants Compact remnants Faint low mass stars GMC r_infl ~2 pc pc Disk formation and migration (Levin 27) Conclusions:. RR is essential for -stars post-capture/migration randomization. 2. Best t model: Tidal capture in dense old cusp of stellar remnants.

9 The hunt for relativistic stars for testing strong gravity,2,3 Option : No old cusp in inner Galactic center (inner RG cusp missing 4,,6 ) All young stars inside. pc observednone strongly relativistic. Low stellar density very slow dynamical evolution. No local stellar targets for tests of strong GR. Option 2: Dark cusp of stellar remnants + old stars further out Rapid e-evolution (RR), but slower a-evolution (NR). tellar destruction (T 7 yr) faster than TE at O( pc). trong depletion of local strongly relativistic stars. Option 3: Dark cusp of stellar remnants + tidally-captured stars Low-mass equivalents of -stars / Hyper-velocity B-stars. Fast, continuous supply rate if scaled by -stars. :Zucker, TA, Gillessen et al 26 2:Will 28 3:Merritt, TA, Mikkola & Will 2 4:Buchholz et al 29 :Do et al 29 6:Bartko et al 2

10 log (P/yr) t = 3.e+2 yr µas/yr e- Q 4e- 2e- 6e µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

11 log (P/yr) t =.e+3 yr µas/yr Q.2 9e- 3e- µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

12 log (P/yr) t = 3.e+3 yr µas/yr Q.8.3. µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

13 log (P/yr) t =.e+4 yr µas/yr Q µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

14 log (P/yr) t = 3.e+4 yr µas/yr Q µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

15 log (P/yr) t =.e+ yr µas/yr Q.3.6. µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

16 log (P/yr) t = 3.e+ yr µas/yr Q.6..2 µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

17 log (P/yr) t =.e+6 yr µas/yr Q..2.3 µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

18 log (P/yr) t = 3.e+6 yr µas/yr Q µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

19 log (P/yr) t =.e+7 yr µas/yr e Q µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

20 log (P/yr) t = 3.e+7 yr µas/yr 2e Q.3.4. µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

21 log (P/yr) t =.e+8 yr µas/yr 4e+ e Q.4.4. µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

22 log (P/yr) t = 3.e+8 yr µas/yr e+ 2e Q.4.4. µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

23 log (P/yr) t =.e+9 yr µas/yr e+ 2e Q.4.4. µas/yr log (-e) - absovich, Bar-Or & TA, 26, in prep.

24 ummary ummary Theoretical results (more in Ben Bar-Or's talk) NR, RR, GW dissipation and secular precession can be treated analytically as eective diusion with correlated noise. The steady state depends mostly on NR, which erases AI. General applications Relativistic loss-cone modeling of galactic nuclei in N limit. Plunge / EMRI rates and branching ratios. Implications for the Galactic Center Origin of -stars: Dark cusp + binary capture favored. O() captured low-mass relativistic stars may exist in GC, but strongly relativistic orbits suppressed by tidal interaction with MBH.