X-rays from the Local Bubble

Abstract

Thermal plasma emission in the soft X-ray band (0.1–2.0 keV)is believed to be responsible for the bulk of the X-ray intensityseen from the Local Bubble, a low-density cavity extending over∼ 70–200 pc around the Sun. The state of the hot plasmais still a matter of discussion as previous instrumentation like aboardROSAT was not able to unambiguously distinguish betweenequilibrium and non-equilibrium emission models and thus topin-point the origin of the Local Bubble. Recent missions like DXS, XQC, and XMM-Newton have shed more lighton this subject and observations indicate that collisional ionizationequilibrium with solar abundances cannot explain the data: lines appear at positions and with intensities in contradictionto standard models. Analysis of EPIC-pn data of X-ray shadowing observations (MBM 12,Ophiuchus molecular cloud) suggest a componentwith higher temperature (kT∼ 0.14 keV) besides thestandard kT∼ 0.09 keV plasma.