Jiren Liu (1), Q. Daniel Wang (2) & Shude Mao (1,3) ((1) National Astronomical Observatories, 20A Datun Road, Beijing 100012, China; (2) Department of Astronomy, University of Massachusetts, Amherst, MA 01002, USA; (3) Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester, M13 9PL, UK)
We present a spatial analysis of the soft X-ray and Hα emissions from the outflow of the starburst galaxy M82. We find that the two emissions are tightly correlated on various scales. The O VII triplet of M82, as resolved by X-ray grating observations of XMM-Newton, is dominated by the forbidden line, inconsistent with the thermal prediction. The O VII triplet also shows some spatial variations. We discuss three possible explanations for the observed O VII triplet, including the charge exchange at interfaces between the hot outflow and neutral cool gas, a collisional non-equilibrium-ionization recombining plasma, and resonance scattering.
Complete preprint ==> http://arxiv.org/abs/1204.3357