Fraction of bolometric luminosity absorbed by dust in DustPedia galaxies

Abstract

Aims. We study the fraction of stellar radiation absorbed by dust, f abs , in 814 galaxies of different morphological types. The targets constitute the vast majority (93%) of the DustPedia sample, including almost all large (optical diameter larger than 1 ′ ), nearby (v ≤ 3000 km s −1 ) galaxies observed with the Herschel Space Observatory. Methods. For each object, we model the spectral energy distribution from the ultraviolet to the sub-millimetre using the dedicated, aperture-matched DustPedia photometry and the fitting code CIGALE. The value of f abs is obtained from the total luminosity emitted by dust and from the bolometric luminosity, which are estimated by the fit. Results. On average, 19% of the stellar radiation is absorbed by dust in DustPedia galaxies. The fraction rises to 25% if only late-type galaxies are considered. The dependence of f abs on morphology, showing a peak for Sb-Sc galaxies, is weak; it reflects a stronger, yet broad, positive correlation with the bolometric luminosity, which is identified for late-type, disk-dominated, high-specific-starformation rate, gas-rich objects. We find no variation of f abs with inclination, at odds with radiative transfer models of edge-on galaxies. These results call for a self-consistent modelling of the evolution of the dust mass and geometry along the build-up of the stellar content. We also provide template spectral energy distributions in bins of morphology and luminosity and study the variation of f abs with stellar mass and specific star formation rate. We confirm that the local Universe is missing the high f abs , luminous and actively star-forming objects necessary to explain the energy budget in observations of the extragalactic background light.

Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample

“…In comparison, a slight offset is seen for the Ref-100 sample, which is expected considering the Recal-25 run has a higher resolution and better sampled disks (Trayford et al 2017). For a galaxy property that depends on the geometry of a galaxy, such as f abs (Viaene et al 2016;Bianchi et al 2018), a sample with more realistic spiral galaxies will reach a better agreement with observations. Based on Fig.…”

“…This ratio contains information on how optically thick a galaxy is, which further depends on the amount, composition, and geometry of dust in a galaxy. Previously, studies reported the average value of f abs to be 0.25 ± 0.05 with the highest value for late-type galaxies (Davies et al 2012;Viaene et al 2016;Bianchi et al 2018, and references therein).…”

“…We discuss in later sections how these differences affect our comparison. We chose not to change the IMF, the dust model or any other parameter in the SED modelling, for the consistency, and easier comparison with the previous studies of the DustPedia galaxies (Bianchi et al 2018;Clark et al 2018;De Vis et al 2019;Nersesian et al 2019;Dobbels et al 2020;Casasola et al 2020, etc.). Additionally, the same cigale fitting procedure for the EAGLE galaxies is already published in Baes et al (2019).…”

“…The most extensive study of f abs is by Bianchi et al (2018), where they used cigale to investigate the extent to which dust affect the stellar light in the DustPedia sample, and its correlation with different galaxy properties. They find weak trends with morphological type and some physical properties (e.g.…”

A radiative transfer model for the spiral galaxy M33★

“…7 also shows the intrinsic stellar SED of M33 (as it would be observed in the absence of dust), with the difference between the apparent (black) and intrinsic (purple) model SED representing the absorption by dust. We have calculated that 35±3% of the stellar light is absorbed by dust and re-emitted in the far-infrared, which is a typical value for late-type spiral galaxies Viaene et al 2016;Bianchi et al 2018). Another aspect of interest shown by Fig.…”