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The Guilty Secrets of Dust in Nearby Galaxies

Chris Clark
December 28, 2017
48

The Guilty Secrets of Dust in Nearby Galaxies

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

Chris Clark

December 28, 2017
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Transcript

  1. ϰ
    d
    Chris Clark
    Simon Schofield
    Haley Gomez
    Jonathan Davies

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  2. The Elusive ϰ
    d
    Chris Clark

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

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  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

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  5. Chris Clark

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  7. An Empirical Value For κ
    d
    • Κ
    500
    = 0.051 m2 kg-1 (+/- ~0.24 dex)
    Chris Clark

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  8. Chris Clark

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  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).

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  10. Chris Clark

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