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Dust model of the ISM PAH bands in starburst nuclei Monte Carlo r adiative transfer

PAH in 3D. Frank Heymann (PhD) Endrik Kr ű gel. Dust model of the ISM PAH bands in starburst nuclei Monte Carlo r adiative transfer PAH destruction in T Tauri disks . dust’1990. PAH in 3D. 1: polarisation. spheroids. Voshchinnikov (2004). 2: ‘’2200” bump +

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Dust model of the ISM PAH bands in starburst nuclei Monte Carlo r adiative transfer

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  1. PAH in 3D Frank Heymann (PhD) EndrikKrűgel • Dust model of the ISM • PAH bands in starburst nuclei • Monte Carlo radiativetransfer • PAH destruction in T Tauridisks

  2. dust’1990 PAH in 3D

  3. 1:polarisation spheroids Voshchinnikov (2004)

  4. 2: ‘’2200” bump + 3: PAH absorption Vertraete et al. 1992 Malloci et al. 2007 Schutte et al. 1993 gr PAH

  5. extinction’2010 Si + aC : 60Å < a < 0.2-0.3µm, ~a-3.5 Graphite : 5Å < a < 80 Å , ~a-3.5 PAH : 30, 200 C ISM [g] : 0.66Si + 0.22aC + 0.07gr + 0.05 PAH [g]

  6. mean I S R F

  7. 4: abundance + 5: PAH bands “Carbon crisis” abundances [ppm]: 31Si + 150aC + 50gr + 30PAH

  8. dust’2010

  9. ISO HD97300 Boulanger et al. (1998) Siebenmorgen et al. (1998)

  10. Radiative transfer in SB NGC1808 Siebenmorgen et al. (2001)

  11. post ISO 17 features

  12. post ISO Siebenmorgen et al. (2001)

  13. post Spitzer • SED model grid: • luminosity • size • mass Siebenmorgen et al. (2007)

  14. high z Efstathiou & Siebenmorgen (2009)

  15. Monte Carlo • Arbitrary dust distribution • Pseudo adaptive mesh geometry Original code by Krűgel (2006)

  16. Monte Carlo • Source emits “photon packages” of equal energy geometry source

  17. Monte Carlo = - ln(ζ) • absorption/ scattering / no interaction geometry source inter-action dust temperature

  18. Monte Carlo • Photons escape model cloud geometry source inter-action temperature detection

  19. Monte Carlo + PAH • store PAH absorption events of each cell • compute PAH emission • neglect PAH self absorption

  20. Multiple photons at a time: MC parallelization • Cell locked when hit byphoton • Parallel random number generator(Mersene Twister) • Computer games Graphical Processing Units (CUDA)

  21. 1D benchmark sphere Iveciz (99)

  22. T* = 2500K ρ(r) = const. 1D benchmark sphere 1 AV=10 100 1000 mag ~5% for 0

  23. MC methods

  24. Monte Carlo + PAH

  25. Disk: T* = 5800K L * = Lsun ρ(r) : hydro static equilibrium (Chiang & Goldreich 1997) 2D benchmark Pascucci et al (2004)

  26. 2D benchmark disk 1 = 10 100 face-on edge-on ~10% for 0

  27. 3D proto-planetary disk + spiral T* = 5800K L * = Lsun Av =10mag 8au MHD (Fargo) density 3au

  28. 3D proto-planetary disk + spiral

  29. ELT 42m PAH imaging

  30. ELT 42m PAH imaging • D = 50pc • 50mas • at 11.3μm • PSF dual band + coronograph

  31. PAH imaging • D = 50pc • 50mas • at 11.3μm (μJy/px) gap /px

  32. T Tauri stars PAH detection rate: HerbigAeBe 60% TTS 10%

  33. T Tauri stars

  34. PAH in a mono-energetic heating bath if | Uf– Ui– hν | < ½ ΔUf : Afi = KνFν/ hν Siebenmorgen & Krűgel (2010)

  35. PAH destruction Eo T [K] tcool time Unimolecular dissociation: Arrhenius form: tdis~ exp(Eo/kT) / ν0«tcool/f ~ 1s Tmin = Eo/k ln(ν0) ~2000K; Eb ~ 5eV; ν0 = 1013Hz ΔE = 3NckTmin ~ 0.1 Nc.Eo=> Nc < 2 ΔE /[eV] (PAH unstable) tabs ~ 1h Omont (1986); Micedlotta et al. (2010); Tielens (2005)

  36. PAH destruction Eo Unimolecular dissociation: tdis ~ exp(Eo/kT) / ν0«tcool/f ~ 1s Tmin = Eo/k ln(ν0) ~2000K;Eo~ 5eV ΔE = 3NckTmin ~ 0.1 Nc.Eo=> Nc < 2 ΔE /[eV] (PAH unstable) single hard photon : independent of distance many soft photons : ~ 1AU

  37. Stationary diskSufficient X-ray photons? z α τ = 1 } ℓ top surface layer Σℓ= α/κ I # C in PAH = hν ∙ 4πr2/Lκ # hard γ absorption/sec << TT phase ‘PAH removal time’

  38. PAH replenishment Vertical mixing in disk? ℓ /v┴ = texp> NC tabs Siebenmorgen & Krűgel (2010)

  39. Future MC model of T Tauridisks • Heating: • photosph.+FEUV + X-rays • Dust + Gas • Density structure • PAH • emission + destruction

  40. Conclusion ?

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