www.dark-cosmology.dk/~pela

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):