List of Figures

View Image Figure 1:
Artistic impression of cascading sound cones (in the geometrical acoustics limit) forming an acoustic black hole when supersonic flow tips the sound cones past the vertical.
View Image Figure 2:
Artistic impression of trapped waves (in the physical acoustics limit) forming an acoustic black hole when supersonic flow forces the waves to move downstream.
View Image Figure 3:
A moving fluid will drag sound pulses along with it.
View Image Figure 4:
A moving fluid will tip the “sound cones” as it moves. Supersonic flow will tip the sound cones past the vertical.
View Image Figure 5:
A moving fluid can form “trapped surfaces” when supersonic flow tips the sound cones past the vertical.
View Image Figure 6:
A moving fluid can form an “acoustic horizon” when supersonic flow prevents upstream motion of sound waves.
View Image Figure 7:
A collapsing vortex geometry (draining bathtub): The green spirals denote streamlines of the fluid flow. The outer circle represents the ergo-surface (ergo-circle) while the inner circle represents the [outer] event horizon.
View Image Figure 8:
Conformal diagram of an acoustic black hole.
View Image Figure 9:
Conformal diagram of an acoustic black-hole–white-hole pair. Note the complete absence of singularities.
View Image Figure 10:
Gravity waves in a shallow fluid basin with a background horizontal flow.
View Image Figure 11:
Domain wall configuration in 3He.
View Image Figure 12:
Ripplons in the interface between two sliding superfluids.
View Image Figure 13:
The graphene hexagonal lattice is made of two inter-penetrating triangular lattices. Each is associated with one Fermi point.
View Image Figure 14:
Velocity profile for a left going flow; the profile is dynamically modified with time so that it reaches the profile with a sonic point at the asymptotic future.
View Image Figure 15:
The picture shows a subsonic dispersion relation as a relation ω − vk = ±c |k|Γ k. In particular we plot a dispersion of the type ∘ -------2---2- Γ k = K tanh (k ∕K ) originally employed by Unruh. For supersonic velocities the dispersion relation has two real roots. For subsonic velocities and ω greater than a critical frequency ωc, the dispersion relation has four real roots.
View Image Figure 16:
The picture shows a supersonic dispersion relation as a relation ω − vk = ±c |k|Γ k. In particular, we plot a dispersion of the type ∘ ----------- Γ k = 1 + k2 ∕K2. For supersonic velocities the dispersion relation has two real roots. For supersonic velocities and ω less than a critical frequency ωc, the dispersion relation has four real roots.
View Image Figure 17:
One-dimensional velocity profile with a black-hole horizon.
View Image Figure 18:
One-dimensional velocity profile with a white-hole horizon.
View Image Figure 19:
One-dimensional velocity profile with a black-hole horizon and a white-hole horizon.
View Image Figure 20:
One-dimensional velocity profile in a ring; the fluid flow exhibits two sonic horizons, one of black hole type and the other of white-hole type.