Pulsar Scintillation Arcs reveal filaments in the Interstellar Plasma

Both forward and reverse Scintillation Arcs are seen in observations of several pulsars. We study the arcs, which are seen in the 2‐D Fourier transform of the dynamic spectrum, from PSRs $\mathrm{B}\text{0834+06}$ and $\mathrm{B}\text{1737+13.}$ In both cases we conclude that the underlying scattered image is highly extended along an axis and also highly modulated along that axis. The corresponding spatial structure in the ionized interstellar medium must be bundles of spaghetti‐like filaments—highly anisotropic turbulence (on scales of 1000–10000 km) which is also very intermittent on scales of an AU. We speculate on their possible origin as remnant turbulence from long past supernovae.