1. 9/7/04Claus Leitherer: A Far-UV View1 Claus Leitherer (STScI) A Far-Ultraviolet View of Starburst Galaxies Claus Leitherer (STScI)

2. 9/7/04Claus Leitherer: A Far-UV View2 Kinney et al. (1994): 1200 – 10,000 Å

3. 9/7/04Claus Leitherer: A Far-UV View3 Leitherer et al. (2002): 900 – 1200 Å

4. 9/7/04Claus Leitherer: A Far-UV View4 Outline  Stellar Populations  Dust Obscuration  Gas: Hot and Cold Phases  Gas: Lyman Continuum

5. 9/7/04Claus Leitherer: A Far-UV View5 Stellar Populations  Far-UV lines: Age-IMF degeneracy  Far-UV continuum: Age-Reddening degeneracy

6. 9/7/04Claus Leitherer: A Far-UV View6 Robert et al. (2003):  Synthetic far-UV spectrum of SSP  Strongest lines: O VI 1035; C III 1175  C III: radiative  O VI: non-radiative  O VI decoupled from stellar parameters  O VI constant with T eff for T eff > 30,000 K

7. 9/7/04Claus Leitherer: A Far-UV View7 Robert et al. (2003):  Trade between age and IMF  IMF slopes with  = 3.3, 2.35, 1.5  C III varies, O VI is constant  Changing M affects L more than T eff  C III, a radiative wind line, scales with L

8. 9/7/04Claus Leitherer: A Far-UV View8 Leitherer et al. (2002):  Trade between age and reddening  HUT spectrum, synth. line spectrum, synth. continuum  Age from Si IV+C IV  Reddening from 1500 Å slope  Use far-UV reddening law  Predict galaxy spectrum down to Lyman limit

9. 9/7/04Claus Leitherer: A Far-UV View9 Dust Obscuration  Reddening shortward of 1200 Å studied by Voyager, HUT, ORFEUS, and FUSE (+ sounding rockets)  Extragalactic studies:  HUT: Leitherer et al. (2002)  FUSE: Buat et al. (2002)

10. 9/7/04Claus Leitherer: A Far-UV View10 Buat et al. (2002):  950 – 1175 Å  reddening law is flatter than Galactic law  Extension of “Calzetti” curve  Agrees with model for clumps + shell geometry  Most stars totally hidden; light comes from few stars with little attenuation

11. 9/7/04Claus Leitherer: A Far-UV View11 Gas: Hot and Cold Phases  The spectral region 912 – 1200 Å includes includes transitions of the hottest (10 5 K) and coldest (10 2 K) gas  Coronal gas traced by O VI  Molecular gas traced by rotational/vibrational transitions of H 2

12. 9/7/04Claus Leitherer: A Far-UV View12 Heckman et al. (2001): NGC 1705 with FUSE

13. 9/7/04Claus Leitherer: A Far-UV View13  Detection of broad (100 km s –1 ), blueshifted (–77 km s –1 ) O VI  Formation in a blow-out from expanding superbubble  N(O VI) consistent with shock-heated gas cooling radiatively  Cooling rate << supernova heating rate  Radiative losses are negligible and wind continues to expand  Implications for IGM enrichment

14. 9/7/04Claus Leitherer: A Far-UV View14 Hoopes et al. (2004): H 2 in starburst galaxies

15. 9/7/04Claus Leitherer: A Far-UV View15  Weak H 2 absorption detected in two out of five starburst galaxies  Upper limit of total M(H 2 )  10 M   Therefore, most of the molecular gas is missed by the FUSE sightlines  Diffuse ISM has little H 2, probably because of the destructive UV radiation  H 2 located in dense clouds with covering factor < 1  clumpy ISM

16. 9/7/04Claus Leitherer: A Far-UV View16 Gas: Lyman Continuum  Star-forming galaxies are the dominant contributor to the non-ionizing radiation field  Are starburst galaxies a significant component of the ionizing background?  Local tests: need far-UV observations  High-z galaxies: IGM radiative transfer

17. 9/7/04Claus Leitherer: A Far-UV View17 Deharveng et al. (2001): Mrk 54 with FUSE

18. 9/7/04Claus Leitherer: A Far-UV View18 Malkan et al. (2003): 11 blue galaxies with STIS

19. 9/7/04Claus Leitherer: A Far-UV View19 Attempts to detect Lyman continuum radiation Leitherer et al. (1995)HUT4 galaxies; z  0< 3 % Hurwitz et al. (1997)HUT4 galaxies; z  0< 19% Deharveng et al. (1997) H  /UV LF in local universe< 1% Deharveng et al. (2001)FUSEMrk 54; z  0< 5% Giallongo et al. (2002)FORS2z = 2.96, 3.32< 16% Fernández-Soto et al. (2003)WFPC2HDF; 1.9 < z < 3.5< 4% Malkan et al. (2003)STIS1.1 < z < 1.4< 1% Steidel et al. (2001)Keck29 galaxies; z = 3.4100%

20. 9/7/04Claus Leitherer: A Far-UV View20 Steidel et al. (2001) Haehnelt et al. (2001)