Orbital Evolution of Gas-driven Inspirals with Extreme Mass Ratios: Retrograde Eccentric Orbits
Abstract
Using two-dimensional simulations, we compute the torque and rate of work (power) on a low-mass gravitational body, with softening length Rsoft, embedded in a gaseous disk when its orbit is eccentric and retrograde with respect to the disk. We explore orbital eccentricities e between 0 and 0.6. We find that the power has its maximum at e ≃ 0.25(h/0.05)2/3, where h is the aspect ratio of the disk. We show that the power and the torque converge to the values predicted in the local (nonresonant) approximation of the dynamical friction (DF) when Rsoft tends to zero. For retrograde inspirals with mass ratios ≲5 × 10-4 embedded in disks with h ≥ 0.025, our simulations suggest that (I) the rate of inspiral barely depends on the orbital eccentricity and (II) the local approximation provides the value of this inspiral rate within a factor of 1.5. The implications of the results for the orbital evolution of extreme mass ratio inspirals are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2020
- DOI:
- 10.3847/1538-4357/ab9b2d
- arXiv:
- arXiv:2006.10206
- Bibcode:
- 2020ApJ...897..142S
- Keywords:
-
- Active galactic nuclei;
- Supermassive black holes;
- Gravitational interaction;
- Dynamical friction;
- Tidal interaction;
- Hydrodynamical simulations;
- Galaxy accretion disks;
- Compact objects;
- 669;
- 16;
- 288;
- 562;
- 1699;
- 422;
- 1663;
- 767;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 17 pages, 24 figures, accepted for publication in ApJ