The bolometric and UV attenuation in normal spiral galaxies of the Herschel Reference Survey⋆
Abstract
The dust in nearby galaxies absorbs a fraction of the UV-optical-near-infrared radiation
produced by stars. This energy is consequently re-emitted in the infrared. We investigate
the portion of the stellar radiation absorbed by spiral galaxies from the Herschel
Reference Survey (HRS) by modelling their UV-to-submillimetre spectral energy
distributions. Our models provide an attenuated and intrinsic spectral energy distribution
(SED), from which we find that on average 32% of all starlight is absorbed by dust. We define the UV heating
fraction as the percentage of dust luminosity that comes from absorbed UV photons and find
this to be 56%, on average.
This percentage varies with morphological type, with later types having significantly
higher UV heating fractions. We find a strong correlation between the UV heating fraction
and specific star formation rate and provide a power-law fit. Our models allow us to
revisit the IRX – AFUV relations, and
derive these quantities directly within a self-consistent framework. We calibrate this
relation for different bins of NUV − r colour and provide simple
relations to relate these parameters. We investigated the robustness of our method and
conclude that the derived parameters are reliable within the uncertainties that are
inherent to the adopted SED model. This calls for a deeper investigation of how well
extinction and attenuation can be determined through panchromatic SED modelling.
Origin : Publication funded by an institution
Loading...