THE WARM AND HOT ISM IN AND NEAR THE MILKY WAY Blair Savage, Mike Shull, Ken Sembach, BarryWelsh, Charles Danforth, and the COS Science team ___________________________________ COS G130M and 160M observations of 10 AGNs situated beyond Milky Way high velocity clouds containing O VI S/N =30 to 40 observations of ISM C IV, Si IV and NV. 28 Orbits

The High Velocity H I + O VI Sky (Sembach et al. 2003, ApJ, ) H I 21cm Emission O VI Absorption 60% OF THE 100 EXTRAGALACTIC LINES OF SIGHT HAVE HIGH VELOCITY O VI WHICH OFTEN IS ASSOCIATED WITH H I HVCs THE H I HVCs ARE INTERACTING WITH THE GAS IN THE GALACTIC THICK DISK AND WITH AN EXTENDED (R >50 kpc) HOT GALACTIC CORONA

High Ionization ISM / IGM Species CIE: Sutherland & Dopita (1993, ApJS, 88, 253) Abundances: Anders & Grevesse (1989,Geochim. Cosmochim Acta, 53, 197) XMM/Chandra O VII,O VIII FUSE O VI, S VI HST N V, C IV, Si IV ISM COOLNG CURVE PEAKS NEAR T ~10 5 to 3x10 5 K A MAJOR COOLANT IS EMISSION FROM O VI

1.PRIMARY FOCUS: THE ORIGINS OF THE HIGHLY IONIZED GAS. 2. DIFFERENT IONIZATION ORIGIN MODELS MAKE DIFFERENT PREDICITONS FOR IONIC RATIOS AND RELATIONSHIPS BETWEEN LOW AND HIGH IONS. 3. THE HIGH ION PROFILES OF O VI, N V, C IV AND Si IV WILL BE INTERCOMPARED AND RELATED TO LOW ION PROFILES (O I, S II, Si II, Fe II, etc.) IN ORDER TO EVALUATE THE PHYSICAL CONDITIONS IN AND ORIGINS OF THE HIGHLY IONIZED GAS IN AND NEAR THE MILKY WAY AT LOW AND AT HIGH VELOCITY. 4. OTHER STUDIES WILL BE POSSIBLE WITH THIS DATA SET INCLUDING: STUDIES OF THE ABUNDANCES IN HVCS AND STUDIES OF THE PHYSICAL CONDITIONS AND ABUNDANCES IN LOW REDSHIFT IGM SYSTEMS

ION TO ION RATIOS CAN BE USED TO DISCRIMINATE AMONG DIFFERENT IONIZATION MECHANISMS _______________________ IONIC RATIOS over 20 Km s -1 VELOCITY INTERVALS for 8 EXTRAGALACTIC LINES OF SIGHT FOR THICK DISK GAS _______________________ CONDUCTIVE HEATING & TURBULENT MIXING ARE CONSISTENT WITH MANY DATA POINTS

COS TARGET LIST AGN zORBITSHVC MRK km/s MRK km/s MRK , -133 km/s PG km/s MRK km/s PG km/s ESO 256-G km/s MRK v HVC MRC v HVC MRK v HVC Total = 28

RELATED PROGRAMS WELSH et al. AN ABSORPTION STUDY OF IVCs USING HOT STARS IN GLOBULAR CLUSTERS 15 ORBITS 10 STARS S/N =30 G130M & G160M WELSH et al. SAMPLING THE LISM WITH HOT WHITE DWARFS 5 ORBITS 5 WHITE DWARFS S/N = 30 G130M& G160M WELSH et al. HIGH RESOLUTION OBSERVATIONS OF THE LISM WITH STIS 4 ORBITS 4 HOT STARS S/N = 50 NOTE THAT ALL EXTRAGALACTIC IGM PROGRAMS WITH S/N > 20 WITH THE G130M &G160M MODES WILL PROVIDE IMPORTANT INFORMATION ABOUT THE HIGH IONS IN AND NEAR THE MILKY WAY