Effects of Solar Activity on the Local Interstellar Magnetic Field Observed by Voyager 1 and IBEX

Abstract

Interstellar Boundary Explorer ( IBEX ) observations have shown enhanced energetic neutral atom emission from a narrow, circular ribbon likely centered on the direction of the magnetic field in the local interstellar medium (LISM). IBEX observations are compared to Voyager   1 's direct observations of the magnetic field in the LISM, which reveals structured changes that are shown here to be driven by pressure fluctuations transmitted across the heliopause boundary separating the LISM from the shocked solar wind beyond the termination shock. The changes in the local interstellar magnetic field observed by Voyager   1 occurred in 2015 and 2016, when the most powerful coronal mass ejections released from the Sun over the last 11-year solar cycle arrived in the outer heliosphere. These events propagated over more than two years through the solar system, ultimately pounding the heliopause and causing transient deviations of the magnetic fields detected by Voyager   1 in the LISM. Thus, we identify the response in pressure variations at Voyager   1 in the LISM with the activity of major solar events several years earlier, during the most active period of the last solar maximum.