The origin of hot gas in the halos of Milky Way-like spiral galaxies

We propose to observe 3 edgeon MilkyWaylike normal spiral galaxies in orderto constrain the presence, properties and physical origin of hot gas in theirhalos, a topic about which relatively little is currently known. Theseobservations will complete our sample of 8 edgeon normal spirals for which wehave a wide range of existing observational data, so that all galaxies will havedeep XMMNewton and/or Chandra observations. With this sample we can assess therelative contribution to the halo Xray emission of normal spirals fromSNIIdriven galactic fountains, accretion of primordial gas, and SNIadrivenoutflows. The observations will robustly detect NGC 891like hot halos, broadlyquantify their properties, and can be used to constrain the efficiency of mechanical energy feedback. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]