Radial Distribution of Stars, Gas, and Dust in Sings Galaxies. II. Derived Dust Properties

The Astrophysical Journal (Impact Factor: 6.73). 08/2009; 701(2):1965. DOI: 10.1088/0004-637X/701/2/1965
Source: arXiv

ABSTRACT We present a detailed analysis of the radial distribution of dust properties in the SINGS sample, performed on a set of ultraviolet (UV), infrared (IR), and H I surface brightness profiles, combined with published molecular gas profiles and metallicity gradients. The internal extinction, derived from the total-IR (TIR)-to-far-UV (FUV) luminosity ratio, decreases with radius, and is larger in Sb-Sbc galaxies. The TIR-to-FUV ratio correlates with the UV spectral slope β, following a sequence shifted to redder UV colors with respect to that of starbursts. The star formation history (SFH) is identified as the main driver of this departure. Both L TIR/L FUV and β correlate well with metallicity, especially in moderately face-on galaxies. The relation shifts to redder colors with increased scatter in more edge-on objects. By applying physical dust models to our radial spectral energy distributions, we have derived radial profiles of the total dust mass surface density, the fraction of the total dust mass contributed by polycyclic aromatic hydrocarbons (PAHs), and the intensity of the radiation field heating the grains. The dust profiles are exponential, their radial scale length being constant from Sb to Sd galaxies (only ~10% larger than the stellar scale length). Many S0/a-Sab galaxies have central depressions in their dust radial distributions. The PAH abundance increases with metallicity for 12 + log(O/H) < 9, and at larger metallicities the trend flattens and even reverses, with the SFH being a plausible underlying driver for this behavior. The dust-to-gas ratio is also well correlated with metallicity and therefore decreases with galactocentric radius. Although most of the total emitted IR power (especially in the outer regions of disks) is contributed by dust grains heated by diffuse starlight with a similar intensity as the local Milky Way radiation field, a small amount of the dust mass (~1%) is required to be exposed to very intense starlight in order to reproduce the observed fluxes at 24 μm, accounting for ~10% of the total integrated IR power.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: By combining Herschel-SPIRE data with archival Spitzer, H i , and CO maps, we investigate the spatial distribution of gas and dust in the two famous grand-design spirals M 99 and M 100 in the Virgo cluster. Thanks to the unique resolution and sensitivity of the Herschel-SPIRE photometer, we are for the first time able to measure the distribution and extent of cool, submillimetre (submm)-emitting dust inside and beyond the optical radius. We compare this with the radial variation in both the gas mass and the metallicity. Although we adopt a model-independent, phenomenological approach, our analysis provides important insights. We find the dust extending to at least the optical radius of the galaxy and showing breaks in its radial profiles at similar positions as the stellar distribution. The colour indices f350/f500 and f250/f350 decrease radially consistent with the temperature decreasing with radius. We also find evidence of an increasing gas to dust ratio with radius in the outer regions of both galaxies.
    åp. 07/2010; 518:L72.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Several recent surveys (HERACLES, NGLS, KINGFISH, VNGS) have provided us with sensitive high-resolution observations of the molecular gas and dust content in spiral galaxies within 25 Mpc. I review recent results on the molecular gas content and its relation to star formation, as well as on the gas to dust ratio and the dust heating in spiral galaxies. I also present new results on the effect of environment on the molecular gas content of spiral galaxies.
    Proceedings of the International Astronomical Union 03/2013; 8(S292):119-126.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Herschel opens a large field of investigations on the hidden star formation in galaxies. Combining UV and far-IR rest-frame data allows us to measure all the star formation in galaxies and to estimate the net dust attenuation. The analysis can be performed from the local universe using far-IR and GALEX surveys to high z (up to z < 2) by combining deep U data with the Herschel observations of the HerMES project. The calibration of dust attenuation, and then star formation rate, is reinvestigated. We present the results of the first analyses performed with Herschel data obtained in the Lockman and COSMOS fields as part of the HerMES project and discuss the reliability of dust attenuation corrections.
    Proceedings of the International Astronomical Union 12/2011; 6(S277):5-8.

Full-text (2 Sources)

Available from
May 28, 2014