Interstellar Neutral Atom Measurements with IBEX and IMAP

Neutral atoms from the interstellar medium around the Sun enter the heliosphere unimpeded by the electromagnetic fields. They bring information about the properties of our interstellar neighborhood, processes at the boundary between the solar and interstellar media, and the direction of the Sun’s motion in the Galaxy. The interstellar neutral atoms of hydrogen, deuterium, helium, neon, and oxygen reach close distances to the Sun where they are probed either by direct detection or remote sensing methods. Here we focus on a direct measurement technique for interstellar neutral atoms of energies from 10 eV to 1 keV on an example of the instruments onboard the Interstellar Boundary Explorer (IBEX) and the follow-up mission the Interstellar Mapping and Acceleration Probe (IMAP, to be launched in 2025). IBEX continuously collects interstellar neutral atom data from the beginning of its operation in 2008 providing a survey over the Solar Cycle 24 despite its observation season being limited during the year. IMAP tracks the beam of interstellar neutrals in the sky throughout the year, which significantly expands scientific opportunities for probing interstellar neutrals from close distances to the Sun. We present the greatest accomplishments of interstellar neutral atom research enabled by IBEX and discuss the science goals in this area for IMAP.

The results are presented in collaboration with scientists and researchers at Southwest Research Institute, the University of Bern, the University of New Hampshire, and Princeton University.