Magnetic Turbulence Intermittency and Compressibility in the Inner Heliosheath and Very Local Interstellar Medium

Abstract We analyze Voyager 1 magnetic field data through 2024 to study fluctuations from the inner heliosheath into the very local interstellar medium (VLISM). We focus on inertial-range intermittency and magnetic compressibility and examine the effects of interstellar shocks and pressure fronts. The heliosheath shows consistently high fluctuation amplitude ( δB / B 0 ∼ 1) and compressibility, indicating the presence of compressive wave modes. The elevated sound speed from pickup ion pressure inhibits wave steepening within the heliosheath, but steepening may occur near or just beyond the heliopause, enabling partial transmission into the VLISM. Beyond the heliopause, magnetic compressibility decreases following the second pressure front at ∼149 au. Intermittency, measured via scale-dependent flatness, also decreases with distance but shows localized enhancements near pressure fronts and shocks in the VLISM. A pronounced peak in flatness at time lags around 10 5 s is observed downstream of the second pressure front, primarily in the parallel magnetic field component, indicating large-scale compressive structures. In contrast, the peak flatness downstream of the first pressure front (at ∼137 au) occurs at shorter time lags, likely due to differences in plasma conditions, structure scales, or elevated noise in the deeper VLISM. An overall decrease in intermittency, approaching near-Gaussian levels, is observed after the second pressure front. However, weak intermittency still persists at small time lags over the past 2 yr, indicating that intermittency does not fully vanish after the magnetic hump.