2026-04-16 マックス・プランク研究所
Reconstruction of how the diffuse X-ray sky should have appeared to eROSITA from May to October 2021. At any given moment, eROSITA has observed only a 1° wide field along its scanning direction, which is indicated by a cyan curve. Each 360° scan took 4 hours and was done approximately perpendicularly to the direction of the Sun, which is located in the overexposed moving region.© K. Dennerl, J. Sanders, H. Brunner & the eSASS team (MPE); E. Churazov, M. Gilfanov (IKI)
＜関連情報＞
- https://www.mpg.de/26381382/space-telescope-studies-solar-system-x-ray-glow
- https://www.science.org/doi/10.1126/science.adt9147
太陽系による軟X線天体への寄与の決定 Determination of the Solar System contribution to the soft X–ray sky
K. Dennerl, G. Ponti, X. Zheng, M. J. Freyberg, […] , and M. C. H. Yeung
Science Published:16 Apr 2026
DOI:https://doi.org/10.1126/science.adt9147
Editor’s summary
Astronomical surveys in soft x-rays detect emission from objects outside the Solar System but also foreground emission from within the heliosphere caused by the solar wind and Earth’s upper atmosphere. Disentangling these sources is challenging because the foreground varies with time, direction, and solar activity. Dennerl et al. used x-ray survey observations taken during a minimum of the Sun’s activity cycle from a location far away from Earth. The researchers separated the heliospheric foreground from the background, allowing each to be studied separately. They also used triangulation to determine where in the heliosphere the x-rays are emitted. —Keith T. Smith
Abstract
Solar wind charged particles interact with diffuse gas within the heliosphere, producing soft x-rays. This solar wind charge exchange (SWCX) process produces foreground emission that complicates interpretation of x-ray observations. In this work, we analyze x-ray observations of the western Galactic hemisphere by the Extended Roentgen Survey with an Imaging Telescope Array (eROSITA) instrument on the Spectrum-Roentgen-Gamma (SRG) spacecraft. These data avoid contamination by Earth’s geocorona and are derived from four surveys of the full sky, including during the minimum of the Sun’s activity cycle. We determine the SWCX contribution and subtract it from the survey, providing a less contaminated view of the diffuse soft x-ray sky. We also demonstrate that x-rays can be used to map the flow of interstellar matter through the Solar System.
