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Lyman α — The Great Escape
Dark Cosmology Centre | Niels Bohr Institutet | Københavns Universitet
Peter Laursen – Paris, 2009
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Lyα escape from high-z galaxies
Why?
What?
How?
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Lyα escape from high-z galaxies
Analytical attempt (Neufeld 1990)
Gas density and temperature Dust density and cross-section
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Neufeld (1991);Hansen & Oh (2006)
Multiphase medium?
Lyα escape from high-z galaxies– Why does Lyα escape after all?
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Kunth et al. (1999);Verhamme et al. (2006);Östlin et al. (2008)
Outflow?
Lyα escape from high-z galaxies– Why does Lyα escape after all?
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Lyα escape from high-z galaxies
Ionized holes?
Kunth et al. (2003);Hayes et al. (2007)
– Why does Lyα escape after all?
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Tenori-Tagle et al. (1999);Mas-Hesse et al. (2003)
Lyα escape from high-z galaxies
Ionized cones +viewing angle?
– Why does Lyα escape after all?
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Numerical approachCosmological N-body + hydro simulation+ Lyα RT on AMR grid with dust
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Dust
Pei (1991) + Weingartner & Draine (2001) + Gnedin et al. (2008)
Four important quantities:
• Cross-section: d()
• Density: nd
• Albedo: A• Phase function: P()
AV NHe.g. Bohlin, Savage & Drake (1978)
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DustFour important quantities:
• Cross-section: d()
• Density: nd
• Albedo: A• Phase function: P()
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DustFour important quantities:
• Cross-section: d()
• Density: nd
• Albedo: A• Phase function: P()
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DustFour important quantities:
• Cross-section: d()
• Density: nd
• Albedo: A• Phase function: P()
10-4 ≥ fion ≥ 1
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Dust
Calzetti et al. (1995); Lillie et al. (1976); Li & Draine (2001)
Four important quantities:
• Cross-section: d()
• Density: nd
• Albedo: A• Phase function: P()
ALyα = 0.32
gLyα = 0.73
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In each cell:LLyα, T, vbulk, nHI, nHII, ZC,N,O,Mg,Si,S,Ca,Fe
Escape
MOCALATA
✞New ñ Scatter/absorb
New and ñ
Interact withgas or dust
Propagate thru ISM
Emit photon
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ResultsSurface brightness map: Without scattering
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ResultsSurface brightness map: With scattering and dust; luminous regions affected more
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ResultsSurface brightness profile: Prominent features smoothed out
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ResultsSurface brightness profile: Dust helps to make profile looks more extended
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ResultsSurface brightness profile: Dust helps to make profile looks more extended
Fynbo et al. (2003)
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ResultsSpectrum: Escape fraction smallest in the wings
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Resultsfesc(Mvir): Escape fraction decreases with galactic mass
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IGM transmission
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Songaila (2004)
IGM transmission
z = 6.3
z = 5.7
z = 3.6
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IGM transmission
z = 6.3
z = 5.7
z = 3.6
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Summary• Many factors help facilitating the escape of Lyα• Spectrum affected in a highly non-grey fashion• fesc decreases with increasing Mvir
• Dust makes SB profile even more extended• Problem can be inversed: Predict results of future observations (e.g. Ultra-VISTA)• You cannot escape the raptor
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Summary• Many factors help facilitating the escape of Lyα• Spectrum affected in a highly non-grey fashion• fesc decreases with increasing Mvir
• Dust makes SB profile even more extended• Problem can be inversed: Predict results of future observations (e.g. Ultra-VISTA)• You cannot escape the raptor
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Summary• Many factors help facilitating the escape of Lyα• Spectrum affected in a highly non-grey fashion• fesc decreases with increasing Mvir
• Dust makes SB profile even more extended• Problem can be inversed: Predict results of future observations (e.g. Ultra-VISTA)• You cannot escape the raptor
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Summary• Many factors help facilitating the escape of Lyα• Spectrum affected in a highly non-grey fashion• fesc decreases with increasing Mvir
• Dust makes SB profile even more extended• Problem can be inversed: Predict results of future observations (e.g. Ultra-VISTA)• You cannot escape the raptor
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Summary• Many factors help facilitating the escape of Lyα• Spectrum affected in a highly non- grey fashion• fesc decreases with increasing Mvir
• Dust makes SB profile even more extended• Problem can be inversed: Predict results of future observations (e.g. Ultra-VISTA)• You cannot escape the raptor
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Extra stuffParameter study: Escape fraction quite insensitive to input parameters
(fortunately/unfortunately)
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Extra stuffParameter study: Escape fraction quite insensitive to input parameters
(fortunately/unfortunately)
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Extra stuffParameter study: Escape fraction quite insensitive to input parameters
(fortunately/unfortunately)
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Extra stuffSimulation parameters (in case of obnoxious question):