10/14/08 Claus Leitherer: UV Spectra of Galaxies 1 Massive Stars in the UV Spectra of Galaxies Claus...
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10/14/08 10/14/08 Claus Leitherer: UV Spectra o Claus Leitherer: UV Spectra o f Galaxies f Galaxies 1 Massive Stars in the Massive Stars in the UV Spectra of UV Spectra of Galaxies Galaxies Claus Leitherer (STScI) Claus Leitherer (STScI)
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Transcript of 10/14/08 Claus Leitherer: UV Spectra of Galaxies 1 Massive Stars in the UV Spectra of Galaxies Claus...
10/14/0810/14/08 Claus Leitherer: UV Spectra of GalaxiesClaus Leitherer: UV Spectra of Galaxies 11
Massive Stars in the Massive Stars in the UV Spectra of GalaxiesUV Spectra of Galaxies
Claus Leitherer (STScI)Claus Leitherer (STScI)
10/14/0810/14/08 Claus Leitherer: UV Spectra of GalaxiesClaus Leitherer: UV Spectra of Galaxies 22
Morton & Spitzer (1965)Morton & Spitzer (1965)
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o Average spectra Average spectra of 16 local SF of 16 local SF galaxies (galaxies (STISSTIS) ) vs. 811 LBGs vs. 811 LBGs ((LRISLRIS))
o Schwartz et al. Schwartz et al. (2006)(2006)
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OutlineOutline
o Galaxy PropertiesGalaxy Properties
o Stellar PopulationStellar Population
o Neutral and Ionized GasNeutral and Ionized Gas
o Lyman-Lyman-αα
o Lyman continuumLyman continuum
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Galaxy PropertiesGalaxy Properties
o UV-bright local star-forming galaxies are of late UV-bright local star-forming galaxies are of late Hubble type, include Irr, BCDs, SB,…..Hubble type, include Irr, BCDs, SB,…..
o Stellar masses of order Stellar masses of order 101088 – 10 – 1099 M M
o Absolute magnitudes Absolute magnitudes MMBB in the range in the range –16 to –19–16 to –19
o Oxygen abundances from Oxygen abundances from 1/20 Z1/20 Z to Zto Z
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o Gil de Paz et al. (2007): Gil de Paz et al. (2007): GALEXGALEX FUV+NUV composite FUV+NUV composite vs. vs. SDSSSDSS image of NGC 5253 image of NGC 5253
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o Goldader et al. Goldader et al. (2002)(2002)
o VV 114VV 114 ( (dd = 83 = 83 Mpc; log Mpc; log LL = = 11.7)11.7)
o Interacting pairInteracting pairo UV vs. IR viewUV vs. IR view
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Stellar PopulationStellar Population
o Satellite UV is sensitive to stars with masses of Satellite UV is sensitive to stars with masses of ~10 M~10 M and above and above
o Continuum: late-O/early-BContinuum: late-O/early-B
o Spectral lines: O stars of all typesSpectral lines: O stars of all types
o Most prominent lines: O VI 1035, N V 1240, Si IV Most prominent lines: O VI 1035, N V 1240, Si IV 1400, C IV 15501400, C IV 1550
10/14/0810/14/08 Claus Leitherer: UV Spectra of GalaxiesClaus Leitherer: UV Spectra of Galaxies 1010
o Chandar et al. (2004)Chandar et al. (2004)o UV line profiles UV line profiles
suggest universal suggest universal Salpeter IMFSalpeter IMF
o N V: 77 eV; C IV: 49 N V: 77 eV; C IV: 49 eV; Si IV: 33 eVeV; Si IV: 33 eV
o Confirmed Confirmed independently by independently by modeling of optical modeling of optical emission lines emission lines (González Delgado et (González Delgado et al. 2002)al. 2002)
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o Beware of selection effects!Beware of selection effects!
o HST slit sizes are small (0.2ʺ for STIS)HST slit sizes are small (0.2ʺ for STIS)
o Massive stars form in clustersMassive stars form in clusters
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o Chandar et al. Chandar et al. (2005)(2005)
o Compare cluster Compare cluster and inter-cluster and inter-cluster spectraspectra
o Inter-cluster Inter-cluster spectra are softerspectra are softer
o IMF or age?IMF or age?o Field population Field population
due to due to dissolving dissolving clustersclusters
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Direct comparison with high-z Direct comparison with high-z galaxies may be misleading galaxies may be misleading
→→ need large- or multi-aperture spectroscopy
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Neutral and Ionized GasNeutral and Ionized Gas
o UV spectral region displays plethora of UV spectral region displays plethora of interstellar linesinterstellar lines
o Spectral region below 1200 Å in particular is Spectral region below 1200 Å in particular is dominated by IS linesdominated by IS lines
o Well-suited for observations with Well-suited for observations with FUSEFUSE because because of wavelength coverage and spectral resolution of wavelength coverage and spectral resolution ((RR ≈ 20,000) ≈ 20,000)
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o Grimes et al. (2008): FUSE survey of local starburst galaxiesGrimes et al. (2008): FUSE survey of local starburst galaxies
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o Grimes et al. (2008)Grimes et al. (2008)o FUSE UV profiles of FUSE UV profiles of
selected IS linesselected IS lineso All lines are blue-All lines are blue-
shifted and shifted and asymmetricasymmetric
o Outflows with Outflows with velocities of order velocities of order ~10~1022 km s km s–1–1
o Galactic superwindsGalactic superwinds
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o LLIRIR + LUV = + LUV = SFRSFR; ; LLKK = = MassMass o Outflow velocity shows trend with SFR/MassOutflow velocity shows trend with SFR/Masso Outflows expected to be more signifcant at high Outflows expected to be more signifcant at high zzo Pollution of the IGM and leakage of radiationPollution of the IGM and leakage of radiation
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Lyman-Lyman-αα
o Leitherer (2007)Leitherer (2007)o Predicted Ly-Predicted Ly-αα
strength for a strength for a standard populationstandard population
o W(Ly-W(Ly-αα) ≈ 10) ≈ 1022 Å Åo Almost never Almost never
observed in the local observed in the local universeuniverse
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o Spectroscopy can cover only a small Spectroscopy can cover only a small solid angle of the Lyman-solid angle of the Lyman-αα emission emission
o HST/ACS Lyman-HST/ACS Lyman-αα imaging survey of imaging survey of local SF galaxies (PI: D. Kunth)local SF galaxies (PI: D. Kunth)
o Haro 11Haro 11: : MMBB = Q 20.5; log O/H = 7.9 = Q 20.5; log O/H = 7.9
o Local analog of a Lyman-break galaxyLocal analog of a Lyman-break galaxy
10/14/0810/14/08 Claus Leitherer: UV Spectra of GalaxiesClaus Leitherer: UV Spectra of Galaxies 2020
o Östlin et al. (2007)Östlin et al. (2007)o Fields: 20’’ Fields: 20’’ 20’’ 20’’
or 8 kpc or 8 kpc 8 kpc 8 kpco Small W(Ly-Small W(Ly-αα) in ) in
the centerthe centero Large W(Ly-Large W(Ly-αα) )
where flux levels where flux levels are smallare small
o Correlates with Correlates with velocity fieldvelocity field but but not with not with E(B-V)E(B-V)
o 2.7% Ly-2.7% Ly-αα escapesescapes
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o Deharveng et al. Deharveng et al. (2008)(2008)
o GALEX survey of Ly-GALEX survey of Ly-αα emitters at emitters at zz ≈ 0.3 ≈ 0.3
o Equivalent width Equivalent width distribution distribution consistent with consistent with observation at high observation at high zz
o Ly-Ly-αα/UV luminosity /UV luminosity function suggests function suggests increase of Ly-increase of Ly-αα escape with redshiftescape with redshift
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Lyman ContinuumLyman Continuum
o Leitherer et al. Leitherer et al. (1999)(1999)
o ~10%~10% of the total of the total luminosity emitted luminosity emitted as ionizing radiationas ionizing radiation
o Observationally Observationally verified via verified via recombination linesrecombination lines
o Leakage?Leakage?
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o Grimes et al. (2008): FUSE survey; 9 galaxies have Grimes et al. (2008): FUSE survey; 9 galaxies have sufficiently high sufficiently high zz to permit Lyman continuum observations to permit Lyman continuum observations
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o Bergvall et al. (2006): detection of Lyman continuum in Bergvall et al. (2006): detection of Lyman continuum in Haro 11 using the same data; 5 – 10% escape fractionHaro 11 using the same data; 5 – 10% escape fraction
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o Alternatively: use Alternatively: use opacity of opacity of interstellar lines interstellar lines as proxy for H I as proxy for H I opacityopacity
o C II 1036C II 1036o Upper limits of a Upper limits of a
few % for escape few % for escape fraction fraction
o Local galaxies Local galaxies are opaqueare opaque
o Reionization?Reionization?
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Main PointsMain Points
o Restframe UV spectra of local and distant star-Restframe UV spectra of local and distant star-forming galaxies are superficially similar but forming galaxies are superficially similar but suggest rather significant differencessuggest rather significant differences
o Beware of Beware of selection effectsselection effects introduced by introduced by aperture sizesaperture sizes
o Mechanical energy inputMechanical energy input by newly formed by newly formed stars is significant and increases with redshiftstars is significant and increases with redshift
o Growing importance of Growing importance of galactic windsgalactic winds, escape , escape of of Ly-Ly-αα, and , and Lyman continuumLyman continuum leakage leakage
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UV spectroscopy with HST UV spectroscopy with HST during C17 and laterduring C17 and later
![Metallicity and Extinction , Emily M. Levesque , Claus ... · arXiv:1504.00011v1 [astro-ph.GA] 31 Mar 2015 October 15, 2018 Ultraviolet ISM Diagnostics for Star-Forming Galaxies I.](https://static.fdocuments.in/doc/165x107/5f8c665a9963b92fbf4814cd/metallicity-and-extinction-emily-m-levesque-claus-arxiv150400011v1-astro-phga.jpg)
