Speaker
Description
The discovery of cometary X-ray emission has revealed the efficiency of charge exchange for the generation of soft X-rays. As this process is characterized by very high cross sections, even tenuous traces of gas can become a source of soft diffuse X-ray emission when exposed to highly ionized solar wind. Such gas is not only present in Earth's exosphere but is also found throughout the solar system, in the form of interstellar particles streaming through it.
Thus, the X-ray glow of geocoronal and heliospheric gas may be present in any observation, affecting all studies of the local hot bubble, the interstellar medium, the galactic corona, the circum-galactic medium, and the cosmic X-ray background. After this fundamental problem had been realized, many attempts have been made to identify and isolate the geocoronal and heliospheric components, but they all face severe limitations, leading to uncertainties which propagate into many studies of the diffuse X-ray emission from beyond. Now, however, a major step forward has been achieved with SRG/eROSITA.
Thanks to its privileged location well outside Earth's exosphere, we see with eROSITA for the first time ever a sky that is free of geocoronal X-ray emission. Furthermore, by having mapped the full sky repeatedly and almost continuously with high grasp for more than two years, eROSITA data have opened up a new window for heliospheric studies. We will show how we utilize this unique treasure for reliably isolating the heliospheric X-ray emission and for investigating its temporal, spatial, and spectral properties in unprecedented detail.
