Alexander V. Semyannikov

Global Acoustic Geometry of Michel Flow in Painlevé-Gullstrand Coordinates

The acoustic metric of spherical accretion onto a Schwarzschild black hole (the Michel flow) in standard coordinates is singular at the gravitational horizon, and inside the acoustic horizon, the coordinate time loses its evolutionary meaning, which hinders the analysis of the su...

Perturbation Spectrum of Michel Flow: Acoustic, Vortical, and Entropy Modes

The spectrum of linear perturbations of relativistic spherical accretion onto a Schwarzschild black hole (Michel flow) is studied, carrying the Newtonian analysis of the spatial stability of Bondi accretion over to full general relativity. Small perturbations of a perfect fluid s...

Acoustic Geometry and Sound-Ray Dynamics in Relativistic Spherical Accretion

In analogue gravity, sound waves in a moving fluid travel along the null geodesics of an effective curved spacetime, giving a controlled setting for studying horizon physics in astrophysical accretion. The relativistic acoustic metric for spherical accretion is well known and has...

Global Acoustic Geometry of Michel Flow in Painlevé-Gullstrand Coordinates

The acoustic metric of spherical accretion onto a Schwarzschild black hole (the Michel flow) in standard coordinates is singular at the gravitational horizon, and inside the acoustic horizon, the coordinate time loses its evolutionary meaning, which hinders the analysis of the su...