ISM d ust model Monte Carlo dust radiative transfer

1. PAH in 3D Shadows, gaps and ring-like structures in proto-planetary disks Ralf Siebenmorgen, Frank Heymann, Nikolai Voshchinikov,EndrikKrűgel Peter Scicluna (PhD) • ISM dust model • Monte Carlodust radiative transfer • Proto-planetary disks: ring-like structures • PAH destruction in proto-planetary disks

2. ISM dust solar neighborhood Abundances [X/H in ppm]: 31Si + 150aC + 50gr + 30PAH Si + aC: 60Å < a < 0.2-0.3µm ~ a-3.5 Graphite : 5Å < a < 80 Å~ a-3.5 PAH : 30, 200 C

3. PAH absorption cross section +‘’2200” bump Verstraete et al. 1992 Malloci et al. (2007)

4. PAH emission cross section starbursts Nucleus of NGC1808 Siebenmorgen et al. (2001,2007)

5. Linear polarisation Serkowski ~Voshchinnikov (2012)

6. Extinction: Prolate/ Sphere

7. ISM dust Fitzpatrick (99)

8. NGC2023 HD37903 Dust model : - Extinction - Emission - Polarisation 8μm Peeters et al. 2012

9. Albedo Extinction

10. Emission

11. Polarisation

12. Circular polarisationof dust: oblate versus prolate x ~maximum of linear polarisation ~Voshchinnikov (2002, 2012)

13. Homogenous versus composite grains ISM Krügel&Siebenmorgen (1994)

14. 3D Monte Carlo Radiative Transfer • Arbitrary dust distribution • Pseudo adaptive mesh geometry

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

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

17. Monte Carlo • Photons escape model cloud geometry source inter-action temperature detection Lightechos: time as 4th dimension?

18. Multiple photons at a time: vectorized MC 100 x faster Challenges: • Cell locked when hit by photon • Parallel random number generator(Mersene Twister) • Graphical Processing Units (CUDA) Heymann & Siebenmorgen (2012)

19. Comparison of 2 ray tracing codes Dust sphere: AV = 1000mag, heated by star K06 : Krügel (2006) Dusty : Ivecizet al. (1999)

20. Sphere T* = 2500K ρ(r) = const. MC versus benchmark 1 AV=10 100 1000 mag ~5% for 0 Heymann & Siebenmorgen (2012)

21. MC methods Heymann & Siebenmorgen (2012)

22. 3D proto-planetary disk + spiral T* = 5800K L * = Lsun Av =10mag 8au MHD (Fargo) density 3au

23. ELT 42m PAH imaging

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

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

26. Shadows in planet forming disks • Gaps and ring-like structures: ... are caused by hydrostatic + radiation balance without the need to postulate a companion/planet (Siebenmorgen & Heymann, 2012). • PAH emission from disks: Low / high detection statistics of PAH in T Tauri / HerbigAe stars is consistent with X-ray destruction of PAH (Siebenmorgen & Krűgel 2010).

27. Gaps and ring-like structures in hydro-dynamical simulations Lagrange et al, β Pic planet detection, Science’10: “…validates the use of disk structures as fingerprints of embedded planets.” Armitage’07

28. Radiative transfer 1D slab geometry ?

29. Puffed up inner rim Dullemond et al.2001 Kama et al. 2010 Shadow Tmid - lower

30. Puffed up second rim Tmid - warmer Shadow Tmid - lower

31. Puffed up third rim

32. Hydrostatic and radiation balance 0) I) T(x,y,z) by MC II)

33. Proto-planetary disk models

34. T Tauri disk

35. Gaps and ring-like structures without planet extinction layer (photosphere) τ(zbot) :=1

36. Gaps and ring-like structures in the mid-IR emission

37. Gaps and ring-like structures in scattered light

38. PAH in 3D PAH emission from disks • PAH detection statistics • PAH excitation / • destruction

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

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

41. MC versus benchmark PAH emission from disks

42. Eo T [K] tcool time PAH destruction Unimolecular dissociation Arrhenius form: tdis ~ exp(Eo/kT) / ν0«tcool ~ 1s Tmin = Eo/k ln(ν0) ~2000K; Eo ~ 5eV; ν0 = 1013Hz ΔE = 3NckTmin ~ 0.1 Nc.Eb => Nc < 2 ΔE /[eV] PAH unstable tabs ~ 1h single hard photon : independent of distance many soft photons : ~AU Siebenmorgen & Krűgel (2010)

43. Stationary diskSufficient X-ray photons? z α τ = 1 } ℓ top extinction layer Σℓ= α/κ I # C in PAH = hν ∙ 4πr2/Lκ # hard γ absorption/sec ‘PAH removal time’ << T Tauripahse

44. Disk lifetime => PAH replenishment Vertical mixing ℓ /v┴ = texp> tdis Siebenmorgen & Krűgel (2010)

45. PAH emission from disks PAH in 3D T Tauri PAH emission from disks

46. PAH in 3D Mid-IR emission from Herbig disks Siebenmorgen & Heymann (2012)

47. Shadows in planet forming disks • Dust model for: • extinction, emission, linear and circular polarisation • Gaps and ring-like structures: ... are caused by hydrostatic + radiation balance without the need to postulate a companion/planet (Siebenmorgen&Heymann, 2012). • PAH emission from disks: Low / high detection statistics of PAH in T Tauri / HerbigAe stars is consistent with X-ray destruction of PAH (Siebenmorgen & Krűgel 2010).

48. PAH band ratios: ionisation dehydrogenation Galiano et al.’08 PAH emission from disks