Ly Scattering in Young Galaxies Under the supervision of.... collaborating with Galaxy Formation and Evolution etc., etc., UCI, Irvine, 2008 DARK Cosmology Centre | Niels Bohr Institutet | Københavns Universitet www.dark-cosmology.dk/~pela

Motivation Fynbo et al. (2003) Surface brightness map Original motivation: Find explanation Surface brightness map Surface brightness profile Fynbo et al. (2003)

Lyman a Cooling radiation (~10%) Stellar sources (~90%) Metagalactic field (~1%) At z = 3 - 4, in the context of galaxy formation, Lyman alpha is produced in a number of ways, the most significant being the ionization and subsequent recombination of hydrogen in the vicinity of young, massive stars. PP67: This should make young galaxies visible. Still, however, for 3 decades none were observed.  Young galaxies should be visible (Partridge & Peebles, 1967)

Analytical models Osterbrock (1962) Harrington (1973) Neufeld (1990) Models were constructed in order to try to explain the null results Osterbrock (1962) Harrington (1973) Neufeld (1990)

Analytical models Dijkstra (2006) Recently extended to more realistic models Dijkstra (2006)

Reality Although the model give us much insight into the physical properties of galaxies and their formation, it is not obvious how consistent their results are with those of more realistic models

Numerical models To solve a problem with such a high number of degrees of freedom, MC is the answer

Cosmological simulations Razoumov & Sommer-Larsen (2006) Sommer-Larsen et al. (2003) Sommer-Larsen (2006)

Monte Carlo L,T,nHI ,vbulk ,Z Interpolate SPH-particle onto grid. The following results are from a uniform grid, 512^3. Code is now able to assume an adaptive grid, giving even higher res. where needed

Monte Carlo Emit photon

Monte Carlo Emit photon  Determine t

Monte Carlo Emit photon  Determine t  Determine uatom

Monte Carlo    Emit photon Determine t Determine uatom ^ Determine n Escape!

Spectra 

Surface brightness maps Photons have a higher probability of escaping in dir. perp. to face of sheet. This may be the only diff between LAEs and LBGs: since continuum photon have appr. the same prob. of esc. in any given dir., they may be detected from any angle while LAEs are more easily detected when viewed face-on.

Surface brightness profiles 

Surface brightness profiles 

Galaxies. Multifarious. Like birds. Damped Ly absorbers, DLAs Distant red galaxies, DRGs Lyman-break galaxies, LBGs Ly emitters, LAEs Sub-mm galaxies, SMGs

Building the bridge Evolutionary sequence? DLA  LAE  LBG  DRG  SMG? Selection effects? LBGs/DLAs probe two diff. ends of hi-z LF Viewing angle?

Dust and IGM absorption AGBs: e.g., Draine (2003) SNe: e.g., Sugerman et al. (2006) QSOs: e.g., Elvis, Marengo, & Karovska (2002) In the present-day Universe, most dust is produced in AGBs. Observations show that dust was also present in the early Universe. Since AGBs take about 1 Gyr to form, something else must have produced the dust at those times. SN? QSO?

Inhomogeneous medium

Adaptive Mesh Refinement Code is now adaptive. Necessary to resolve the clumpy medium, which for certain configurations may enhance the Lya-to-continuum ratio (e.g. Hansen & Oh)

Adaptive Mesh Refinement Code is now adaptive. Necessary to resolve the clumpy medium, which for certain configurations may enhance the Lya-to-continuum ratio (e.g. Hansen & Oh)

Adaptive Mesh Refinement On a (250 kpc)^3 box, smallest cells are ~10 pc.

Properties of dust n: Metals condense to dust , P(,): Three important properties: Amount (n), cross-section(sigma = sigma_abs + sigma_sca), and phase funcion (P) of scattering angle

Properties of dust n: Metals condense to dust , P(,): In principle easy: Three important properties: Amount (n), cross-section(sigma = sigma_abs + sigma_sca), and phase funcion (P) of scattering angle

Properties of dust n: Metals condense to dust , P(,): In principle easy: Three important properties: Amount (n), cross-section(sigma = sigma_abs + sigma_sca), and phase funcion (P) of scattering angle

Properties of dust n: Metals condense to dust , P(,): In principle easy: ...dust grains are not really that simple

Properties of dust Laboratory experiments Lab exp.’s can tell us about the morphologies and compositions of dust. Unfortunately, several different exps can all explain obs.

Properties of dust Laboratory experiments ...however, condensed red wine canNOT explain obs.

Summary Ly scattering responsible for extended halo Ly line profile may reveal gas kinematics Line is broadened ~1000 km s-1 Anisotropic escape of radiation may explain differences in observed properties, and may even link different types of galaxies