1 / 20

LISA double BHs

LISA double BHs. Dynamics in gaseous nuclear disk. Outlines. Dynamical evolution of MBHBs Code introduction Initial conditions of the simulations Results Future work. MBHs coalescence (1). Collisionless background (Begelman, Blanford & Rees 1980). ● Dynamical friction

borka
Download Presentation

LISA double BHs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LISA double BHs Dynamics in gaseous nuclear disk

  2. Outlines • Dynamical evolution of MBHBs • Code introduction • Initial conditions of the simulations • Results • Future work

  3. MBHs coalescence (1) Collisionless background (Begelman, Blanford & Rees 1980) ● Dynamical friction (tidal stripping, efficient only for “major mergers”) ● Three body interactions (loss cone depletion… ask to Sesana) ● Gravitational wave emission

  4. MBHs coalescence (2) Gaseous background ● Dynamical friction (1) (Kazantzidis et al. 2005) ● Dynamical friction (2) (Escala, Larson, Coppi & Maradones 2004) ● Gravitational torque by ellipsoidal deformation (Escala, Larson, Coppi & Maradones 2004) ● Gravitational torque in circumnuclear gap (Armitage & Natarajan 2005) ● Gravitational wave emission

  5. Initial condition Stellar bulge (Plummer): Gaseous disk (Mestel): Equation of state γ = 5/3 (pure adiabatic evolution) P=Kργ

  6. Code: Gadget Springel, Yoshida & White 2001 SPH: Smoothed Particle Hydrodynamics Stellar and gaseous environment are sampled statistically (Monte Carlo) Any “particle” has a spherical distribution of mass:

  7. Code: Gadget Springel, Yoshida & White 2001 Gravitational potential is computed with a tree algorithm Computational cost ~ N log N Cell opening criterion: Ml2/r4 < α2 M/r2 α > r / l (geometrical criterium) Euler equation (for gas particles)

  8. Dotti et al. in preparation MDISK = 10 8 M RDISK = 109 pc MBULGE = 6.98  MDISK a = 55 pc 2.6 × 10 5 K < T < 4.2 × 10 5 K i = 0 º i = 22.5 º i = 45 º i = 67.5 º Parameters varying: BH1 to BH2 mass ratio Eccentricity 0.010.03 0.05 0.1 0.3 0.5 Dotti et al. in preparation Escala et al. 2005 MDISK = 5  10 9 M RDISK = 400 pc MBULGE = 6.98  MDISK a = 200 pc MDISK = 10 8 M RDISK = 109 pc MBULGE = 6.98  MDISK a = 55 pc T ~ 10 4 K Parameters varying: Clumpiness Orbital inclination angle BH to gas mass ratio Parameters varying: BH1 to BH2 mass ratio Eccentricity

  9. Run A: (equal mass / circular)

  10. Run A: (equal mass / circular)

  11. Run B: (equal mass / elliptical)

  12. Predicted by: Colpi et al. 1999 van den Bosch et al. 1999 Run E: (equal mass / elliptical / no gas)

  13. Escala et al. 2004 Run A / B: (equal mass)

  14. Run C: (unequal mass / circular)

  15. Run D: (unequal mass / elliptical)

  16. Run F (unequal mass / elliptical /retrograde )

  17. Sesana et al. in preparation Accretion implications Variation of the mass of one of BHs in binary has some dynamical effects… If angular momentum is conserved:

  18. Scale considerations (1) In my simulation we have a spatial resolution of ~ 1 pc For this separation, the two MBHs can not coalesce in an Hubble time for GW emission. We are preparing higher resolution simulations, but ... “using finer and finer resolution may be a waste of time unless the physics is consistent with the scale” Take home message I, Joe Monaghan.

  19. Scale considerations (2) High resolution simulations (HRSs) could investigate long-scales of the order of accretion radius of ours MBHs, of the local instability of a realistic self gravitating disk, etc. So, HRSs allow (and force) us to implement new features of the code, corresponding to different physical phenomena: • Star formation • Black holes treated as sink particles • Realistic cooling-heating

  20. Scale considerations (3) HRSs imply an increase of computational time With the collaboration of Simone Callegari, a student of Milano Bicocca, we are modifying the code to include an arbitrary static component of the gravitational potential in order to reduce the number of “live” particles without losing resolution As a test, we run a simulation of a Hernquist stellar Bulge in a NFW halo of DM, with an “live” halo and a “dead” halo

More Related