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A Far-Ultraviolet View of Starburst Galaxies Claus Leitherer (STScI)

A Far-Ultraviolet View of Starburst Galaxies Claus Leitherer (STScI). Kinney et al. (1994): 1200 – 10,000 Å. Leitherer et al. (2002): 900 – 1200 Å. Outline. Stellar Populations Dust Obscuration Gas: Hot and Cold Phases Gas: Lyman Continuum. Stellar Populations.

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A Far-Ultraviolet View of Starburst Galaxies Claus Leitherer (STScI)

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  1. A Far-Ultraviolet View of Starburst GalaxiesClaus Leitherer (STScI) Claus Leitherer: A Far-UV View

  2. Kinney et al. (1994): 1200 – 10,000 Å Claus Leitherer: A Far-UV View

  3. Leitherer et al. (2002): 900 – 1200 Å Claus Leitherer: A Far-UV View

  4. Outline • Stellar Populations • Dust Obscuration • Gas: Hot and Cold Phases • Gas: Lyman Continuum Claus Leitherer: A Far-UV View

  5. Stellar Populations • Far-UV lines: Age-IMF degeneracy • Far-UV continuum: Age-Reddening degeneracy Claus Leitherer: A Far-UV View

  6. 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 Teff for Teff > 30,000 K Claus Leitherer: A Far-UV View

  7. 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 Teff • C III, a radiative wind line, scales with L Claus Leitherer: A Far-UV View

  8. 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 Claus Leitherer: A Far-UV View

  9. 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) Claus Leitherer: A Far-UV View

  10. 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 Claus Leitherer: A Far-UV View

  11. Gas: Hot and Cold Phases • The spectral region 912 – 1200 Å includes includes transitions of the hottest (105 K) and coldest (102 K) gas • Coronal gas traced by O VI • Molecular gas traced by rotational/vibrational transitions of H2 Claus Leitherer: A Far-UV View

  12. Heckman et al. (2001): NGC 1705 with FUSE Claus Leitherer: A Far-UV View

  13. 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 Claus Leitherer: A Far-UV View

  14. Hoopes et al. (2004): H2 in starburst galaxies Claus Leitherer: A Far-UV View

  15. Weak H2 absorption detected in two out of five starburst galaxies • Upper limit of total M(H2)  10 M • Therefore, most of the molecular gas is missed by the FUSE sightlines • Diffuse ISM has little H2, probably because of the destructive UV radiation • H2 located in dense clouds with covering factor < 1  clumpy ISM Claus Leitherer: A Far-UV View

  16. 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 Claus Leitherer: A Far-UV View

  17. Deharveng et al. (2001): Mrk 54 withFUSE Claus Leitherer: A Far-UV View

  18. Malkan et al. (2003): 11 blue galaxies withSTIS Claus Leitherer: A Far-UV View

  19. Attempts to detect Lyman continuum radiation Claus Leitherer: A Far-UV View

  20. Steidel et al. (2001) Haehnelt et al. (2001) Claus Leitherer: A Far-UV View

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