$30 off During Our Annual Pro Sale. View Details »

The Guilty Secrets of Dust in Nearby Galaxies

Chris Clark
December 28, 2017

The Guilty Secrets of Dust in Nearby Galaxies

Two-part seminar given to the East Asian Observatory, 2017.

Chris Clark

December 28, 2017


  1. ϰ
    Chris Clark
    Simon Schofield
    Haley Gomez
    Jonathan Davies

    View Slide

  2. The Elusive ϰ
    Chris Clark

    View Slide

  3. M
    = M
    d = Dust mass
    g = Gas mass
    d = ISM dust-to-metals ratio = 0.5 +/- 0.1
    Z = ISM metal mass fraction (ie, ISM metallicty)
    Chris Clark

    View Slide

  4. Improvements Over James et al (2002)
    Using data from the HRS
    • We now have Herschel photometry; James et al only had IRAS &
    SCUBA, and so could not constrain dust temperature.
    • We have integrated (and normalised) ISM metallicites from drift-
    scan spectroscopy
    • We have integrated CO maps; they only had central pointings.
    • James et al did not consider the effect of oxygen depletion on
    their metallicites – we do.
    • James et al did not account for Helium or gas-phase metals in
    their ISM masses – we do.
    Chris Clark

    View Slide

  5. Chris Clark

    View Slide

  6. Chris Clark

    View Slide

  7. An Empirical Value For κ
    • Κ
    = 0.051 m2 kg-1 (+/- ~0.24 dex)
    Chris Clark

    View Slide

  8. Chris Clark

    View Slide

  9. Chris Clark
    DustPedia Overview
    • THEMIS – A physically-motivated dust model based upon
    laboratory observations of astrophysical minerals (see papers by
    A Jones, N Ysard).
    • SKIRT – Radiative transfer modelling suite that can fit a dust
    model to galaxy observations in 3D (see papers by M Baes, P De
    Camps, S Verstoken).
    • A hierarchical Bayesian SED fitting toolkit that can be used to
    model both galaxies both globally and pixel-by-pixel (see papers
    by F Galliano).
    • A database of multiwavelength imagery and photometry database
    for all 876 nearby galaxies observed by Herschel for which
    V<3000 km/s and D25<1’ (see upcoming paper by me).

    View Slide

  10. Chris Clark

    View Slide

  11. View Slide

  12. View Slide

  13. View Slide

  14. View Slide

  15. View Slide

  16. View Slide

  17. View Slide

  18. View Slide

  19. View Slide

  20. View Slide

  21. View Slide

  22. View Slide

  23. View Slide

  24. View Slide

  25. View Slide

  26. View Slide

  27. View Slide

  28. View Slide

  29. View Slide

  30. View Slide

  31. View Slide

  32. View Slide

  33. View Slide

  34. View Slide

  35. View Slide

  36. View Slide

  37. View Slide

  38. View Slide

  39. View Slide