Speaker
Description
The solar neighbourhood is a volume devoid of neutral material. Instead, it is displaced by a soft X-ray-emitting plasma. This region is known as the local hot bubble (LHB). A holistic view of this emission requires a large covering area, first delivered by the ROSAT All Sky Survey about three decades ago. The properties of the LHB were measured but were unfortunately clouded by the discovery of the solar wind charge exchange (SWCX) emission at similar energies emanating from solar wind ions interacting with Earth's exosphere and neutral matter within the heliosphere.
eROSITA's halo orbit around L2 avoided the contamination from the SWCX from the exosphere, and the favourable timing of eRASS1 at solar minimum provided a valuable data set for studying any diffuse emission outside of the Solar System, particularly emissions spanning large areas in the sky, like the LHB. In this talk, I will describe our half-sky spectral analysis of the diffuse soft X-ray background (SXRB), emphasising the isolation and characterisation of the LHB emission. We found a clear North-South temperature dichotomy in the LHB. Its cause is unclear but could be linked to the most recent off-centre supernova explosions that inflated the LHB. The shape of the LHB is much more extended at high Galactic latitudes, presumably due to the higher mid-plane pressure preventing expansion on the disk. We also observed the presence of interstellar tunnels filled with hot plasma, potentially connecting to the nearest superbubbles.
