1 / 45

Lyman-alpha Resonant Scattering in Young Galaxies: Insights from Cosmological Simulations

This presentation by Peter Laursen, under the guidance of supervisors Jesper Sommer-Larsen and Johan Fynbo, explores Lyman-alpha (Lyα) resonant scattering phenomena in young galaxies, focusing on their formation and evolution. The talk delves into the physical background, motivation for the study, and the numerical models developed to simulate and analyze these processes. Results indicate that resonant scattering plays a significant role in the visibility of young galaxies, providing insights into their structure and behavior in the cosmological context.

essien
Télécharger la présentation

Lyman-alpha Resonant Scattering in Young Galaxies: Insights from Cosmological Simulations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lyman a Resonant Scattering in Young Galaxies Master Colloquium --- Peter Laursen Supervisors: Jesper Sommer-Larsen & Johan Fynbo www.dark-cosmology.dk DARK Cosmology Centre| Niels Bohr Institutet | Københavns Universitet

  2. Overview • The title • Motivation • Physical background • Constructing the code • Results • Outlook

  3. Galaxies Lya Resonant Scattering in YoungGalaxies

  4. The cosmological redshift Lya Resonant Scattering inYoungGalaxies

  5. 400 kyr 1100 13.5 Gpc CMB • ~½-1 Gyr ~5-10 8-10 Gpc Galaxy formation • ~2 Gyr ~3-4 6-7 Gpc “Young galaxies” • 13.7 Gyr 0 0 Now The cosmological redshift • tzd Event • 0 14 Gpc Big Bang lobs = (1 + z) lem Lya Resonant Scattering inYoungGalaxies

  6. Lyman a ELya = 10.2 eV l0 = 1216 Å n0 = 2.466 X1015 s-1 LyaResonant Scattering inYoungGalaxies

  7. Lyman a ELya = 0.0000000000000000000004 kcal l0 = 0.00001216 cm n0 = 2.466 million GHz LyaResonant Scattering inYoungGalaxies

  8. Creation of Lya • Cooling radiation (~10%) • Stellar sources (~90%) • Metagalactic field (~1%) •  • Young galaxies should be • visible (Partridge & Peebles, 1967) LyaResonant Scattering inYoungGalaxies

  9. Lyman-break galaxies LyaResonant Scattering inYoungGalaxies

  10. Scattering LyaResonantScatteringinYoungGalaxies

  11. Resonant scattering LyaResonantScatteringinYoungGalaxies

  12. Resonant scattering LyaResonantScatteringinYoungGalaxies

  13. Analytical models • Osterbrock (1962) • Harrington (1973) • Neufeld (1990)

  14. Analytical models • Dijkstra (2006)

  15. Emergent spectrum • Neufeld (1990)

  16. Emergent spectrum • Venemans et al. (2005)

  17. Diffusion in frequency

  18. Gaussian • Voigt Diffusion in frequency • Lorentzian

  19. Diffusion in space • Optical depth: t= r nHIsn • Optical depth: t = r nHIsn • Optical depth: t = r nHIsn • Optical depth: t = r nHIsn

  20. Motivation • Surface brightness map • Surface brightness profile • Fynbo et al. (2003)

  21. Numerical models

  22. Determinen • ^ • Escape! Numerical models • Emit photon •  • Determine t •  • Determine uatom • 

  23. Numerical models • “It would seem that large digital • computers could be applied very • profitably to this problem” • Osterbrock (1962)

  24. Numerical models

  25. Cosmological simulation • - The Movie • Sommer-Larsen et al. (2003); Sommer-Larsen (2006)

  26. Monte Carlo code • L, T, nHI,vbulk

  27. Testing

  28. Testing

  29. Testing

  30. Radiative transfer

  31. Radiative transfer

  32. Observations

  33. Surface brightness maps

  34. Surface brightness profiles

  35. Spectra

  36. Significance of the velocity field

  37. Fitting a Neufeld profile

  38. Uniform cube

  39. Directionality

  40. Surface brightness

  41. Emergent spectrum

  42. Average number of scatterings

  43. Average distance traveled

  44. Summary • Yes – resonant scattering can explain the • appearance of young galaxies • The code as a theoretical probe • Temperature • Velocity field • Column density • Clumpiness of the gas

  45. Outlook • Numerical improvements • Dust • RT of ionizing UV radiation • Lya galaxies at z = 8.8

More Related