Are the heliosphere, very local interstellar medium, and local cavity in pressure balance with Galactic gravity

Abstract

The Voyager spacecraft are providing the first in situ measurements of physical properties in the outer heliosphere beyond the heliopause. These data, together with data from the IBEX and HST spacecraft and physical models consistent with these data, now provide critical measurements of pressures in the heliosphere and surrounding interstellar medium. Using these data, we assemble the first comprehensive survey of total pressures inside and outside of the heliopause, in the interstellar gas surrounding the heliosphere, and in the surrounding Local Cavity to determine whether the total pressures in each region are in balance with each other and with the gravitational pressure exerted by the Galaxy. We inter-compare total pressures in each region that include thermal, non-thermal, plasma, ram, and magnetic pressure components. An important result is the role of dynamic (ram) pressure. Total pressure balance at the heliopause can only be maintained with a substantial contribution of dynamic pressure from inside. Also, total pressure balance between the outer heliosphere and pristine very local ISM (VLISM) and between the pristine VLISM and the Local Cavity requires large dynamic pressure contributions.

15 pages, 1 figure, Astrophysical Journal in press

References in corpus (13)

• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• The Structure of the Local Interstellar Medium V: Electron Densities
• Three-dimensional mapping of the local interstellar medium with composite data
• The search for the origin of the Local Bubble redivivus
• The Boundary Conditions of the Heliosphere: Photoionization Models Constrained by Interstellar and In Situ Data
• The History and Future of the Local and Loop I Bubbles
• Low-frequency Faraday rotation measures towards pulsars using LOFAR: probing the 3-D Galactic halo magnetic field
• The Origin of Radio Scintillation In the Local Interstellar Medium
• Very Local Interstellar Medium Revealed by Complete Solar Cycle of Interstellar Neutral Helium Observations with IBEX
• Mixing Interstellar Clouds Surrounding the Sun
• Slowdown and Heating of Interstellar Neutral Helium by Elastic Collisions Beyond the Heliopause
• Inhomogeneity within Local Interstellar Clouds
• Turbulence and Particle Acceleration in Radiative Shock Waves in the Cygnus Loop II: Development of Postshock Turbulence