ULTRAVIOLET SPECTROSCOPIC ULTRAVIOLET SPECTROSCOPIC STUDIES OF DIFFUSE GAS IN STUDIES OF DIFFUSE GAS IN AND NEAR THE MILKY WAYAND NEAR THE MILKY WAY

BLAIR D. SAVAGEBLAIR D. SAVAGEUNIVERSITY OF WISCONSIN-MADISONUNIVERSITY OF WISCONSIN-MADISON

BACKGROUNDBACKGROUND

DIAGNOSTIC POWER OF THE UVDIAGNOSTIC POWER OF THE UV

SAMPLING OF HST ISM RESULTSSAMPLING OF HST ISM RESULTS

HIGH PRIORITY PROJECTS HIGH PRIORITY PROJECTS

SPIRAL GALAXIES HAVE A COMPLEX SPIRAL GALAXIES HAVE A COMPLEX MULTI-PHASE GASEOUS MEDIUMMULTI-PHASE GASEOUS MEDIUM

(Howk & Savage 1999)(Howk & Savage 1999)

NGC 891 WIYN V BAND IMAGE & UNSHARP MASK IMAGENGC 891 WIYN V BAND IMAGE & UNSHARP MASK IMAGE

0.7 “ seeing ( Howk & Savage 1999)0.7 “ seeing ( Howk & Savage 1999)

FUNDAMENTAL QUESTIONS FUNDAMENTAL QUESTIONS

WHAT IS THE COMPOSITION OF THE GAS?WHAT IS THE COMPOSITION OF THE GAS?

WHAT IS THE DISTRIBUTION OF THE GAS?WHAT IS THE DISTRIBUTION OF THE GAS?

WHAT ARE THE PHYSICAL CONDITIONS OF THE GAS?WHAT ARE THE PHYSICAL CONDITIONS OF THE GAS?

WHAT PHYSICAL PROCESSES CONTROL THESE WHAT PHYSICAL PROCESSES CONTROL THESE CONDITIONSCONDITIONS??

HOW DOES THE INTERSTELLAR GAS PARTICIPATE IN HOW DOES THE INTERSTELLAR GAS PARTICIPATE IN

GALACTIC PROCESSESGALACTIC PROCESSES??

THE DIAGNOSTIC POWER OF UV THE DIAGNOSTIC POWER OF UV SPECTROSCOPY SPECTROSCOPY

ISM ATOMIC SPECIES DETECTED BY HSTISM ATOMIC SPECIES DETECTED BY HSTH I, D IH I, D IB IIB IIC I, CI*, CI**, C II, CII*, C IV C I, CI*, CI**, C II, CII*, C IV N I, N VN I, N VO I, O I* O I, O I* Mg I, Mg IIMg I, Mg IIAl II, Al IIIAl II, Al IIISi I, Si II, Si II*, Si III, Si IVSi I, Si II, Si II*, Si III, Si IVP I, P II, PIIIP I, P II, PIIIS I, S II, S IIIS I, S II, S IIICl ICl ICr II, Mn II, Fe II, Co II, Ni II, Cu II, Zn Cr II, Mn II, Fe II, Co II, Ni II, Cu II, Zn

II,Ga II,II,Ga II,Ge II, As II, Se II, Kr I, Sn II, Tl II, Pb II Ge II, As II, Se II, Kr I, Sn II, Tl II, Pb II

ABUNDANCESABUNDANCESDENSITY DIAGNOSTICSDENSITY DIAGNOSTICSTEMPERATURE DIAGNOSTICSTEMPERATURE DIAGNOSTICSTRACES THE CNM, WNM, WIM, & HIMTRACES THE CNM, WNM, WIM, & HIM

ISM GAS PHASE ABUNDANCESISM GAS PHASE ABUNDANCES

OPH (Savage & Sembach OPH (Savage & Sembach 1996)1996)

GAS PHASE ABUNDANCES GAS PHASE ABUNDANCES IN DIFFERENT ISM REGIONSIN DIFFERENT ISM REGIONS

Spitzer & Fitzpatrick (1993) Savage & Spitzer & Fitzpatrick (1993) Savage & Sembach (1996)Sembach (1996)

COOLING BY C II IN THE MILKY WAY COOLING BY C II IN THE MILKY WAY vsvs

DAMPED LYMAN ALPHA SYSTEMS DAMPED LYMAN ALPHA SYSTEMS

Lehner et al. (2004) Lehner et al. (2004)

ASTROPHYSICAL JOURNAL ASTROPHYSICAL JOURNAL (1956, VOLUME 124, 20)(1956, VOLUME 124, 20)

ON A POSSIBLE INTERSTELLAR ON A POSSIBLE INTERSTELLAR GALACTIC CORONAGALACTIC CORONA

LYMAN SPITZER, JR. LYMAN SPITZER, JR. Princeton University Observatory Princeton University Observatory

Received March 24, 1956Received March 24, 1956

““The ion The ion O VIO VI which is isoelectronic to Mg X, has a which is isoelectronic to Mg X, has a corresponding doublet at 1038 and 1032 Å and might be corresponding doublet at 1038 and 1032 Å and might be sufficiently abundant to produce measurable absorption, sufficiently abundant to produce measurable absorption, especially since the ionization potential of O VII has the especially since the ionization potential of O VII has the relatively high value of 739 volts. Similarly the ultimate lines relatively high value of 739 volts. Similarly the ultimate lines of of N VN V and C IV, at about 1240 and 1550A, respectively, might and C IV, at about 1240 and 1550A, respectively, might be observable.”be observable.”

High Ionization ISM / IGM Species

CIE: Sutherland & Dopita (1993)Abundances: Anders & Grevesse (1989)

EXTENSION OF THE HIGHLY IONIZED IONS INTO THE HALOEXTENSION OF THE HIGHLY IONIZED IONS INTO THE HALO

LYMAN SPITZER’S CORONALYMAN SPITZER’S CORONA

EXPONENTIAL SCALE HEIGHTS (HST +FUSE) EXPONENTIAL SCALE HEIGHTS (HST +FUSE) Si IV 5.1±0.7 kpcSi IV 5.1±0.7 kpcC IV 4.4±0.6 kpcC IV 4.4±0.6 kpcN V 3.3±0.5 kpcN V 3.3±0.5 kpc

O VI 2 to 4 kpc O VI 2 to 4 kpc

HIGHLY IONIZED GAS (O VI) IN AND NEAR THE MILKY WAY

Sembach et al. (2000, ApJ, 538, L31)

H2 model

The High Velocity H I + O VI Sky

H I 21cm EmissionO VI AbsorptionSembach, Wakker, Savage, et al. (2003)

Metallicity: Z ~ 0.1 – 0.2 (Wakker et al. 1999; Gibson et al. 2002)

Distance: d > 5 kpc from the Galactic plane

Mass: MHI > 1.2 x 106 Mo

Complex C has little dust or H2 and its low N abundance implies that it is chemically young (Richter et al. 2001).

Complex C is moving at high negative velocities (–170 to –100 km s-1). O VI absorption is detected at essentially the same velocities as the H I.

High Velocity Cloud Complex C

Nine Complex C sight lines observed

All show O VI absorption at Complex C velocities

N(O VI) 4.7x1013 to 1.7x1014 cm-2 (hot H+ ~ 20% HTOTAL)

v(H I) - v(O VI) = 0± 13 km s-1

Conductive interface model favored (Fox et al. 2003)

Highly Ionized Gas in Complex C

COMPLEX C WARM - HOT GAS INTERFACESCOMPLEX C WARM - HOT GAS INTERFACESFox et al. (2004) Fox et al. (2004)

3C273

ROSAT All-Sky Survey(Snowden et al. 1997, ApJ, 485, 125)

Chandra X-ray O VII absorption(Fang et al. 2003, ApJ, 586, L49)

PKS 2155-304

Mrk 421NGC 4593

A SAMPLING OF HIGH PRIORITY ISM A SAMPLING OF HIGH PRIORITY ISM PROJECTSPROJECTS

1.1. WHAT ARE THE PROPERTIES OF CONDUCTIVE INTERFACES?WHAT ARE THE PROPERTIES OF CONDUCTIVE INTERFACES?

Best explored along simple LISM lines of sight toward bright Best explored along simple LISM lines of sight toward bright white dwarfs.white dwarfs.~60 orbits of STIS E140M observations~60 orbits of STIS E140M observations

2.2. WHAT ARE THE PROPERTIES OF THE VERY HIGHLY WHAT ARE THE PROPERTIES OF THE VERY HIGHLY EXTENDED GASEOUS ENVIRONMENT OF THE MILKY WAY?EXTENDED GASEOUS ENVIRONMENT OF THE MILKY WAY?

~250 orbits of STIS E140M observations of 10 AGNs ~250 orbits of STIS E140M observations of 10 AGNs sampling HVCs interacting with gas in the outer sampling HVCs interacting with gas in the outer environment of the Milky Way.environment of the Milky Way.

3.3. WHAT ARE THE FUNDAMENTAL PROPERTIES OF THE ISM IN WHAT ARE THE FUNDAMENTAL PROPERTIES OF THE ISM IN

AN IRREGULAR GALAXY?AN IRREGULAR GALAXY? ~300 orbits of STIS E140M, E230M, E140H, & E230H ~300 orbits of STIS E140M, E230M, E140H, & E230H

observations of LMC stars. observations of LMC stars.

WHAT ARE THE FUNDAMENTAL PROPERTIES OF THE WHAT ARE THE FUNDAMENTAL PROPERTIES OF THE ISM IN AN IRREGULAR GALAXY?ISM IN AN IRREGULAR GALAXY?

HHImagery (Danforth et al. 2002) O VI (Howk et al. 2002) Imagery (Danforth et al. 2002) O VI (Howk et al. 2002)