Bibcode
Boquien, M.; Kennicutt, R.; Calzetti, D.; Dale, D.; Galametz, M.; Sauvage, M.; Croxall, K.; Draine, B.; Kirkpatrick, A.; Kumari, N.; Hunt, L.; De Looze, I.; Pellegrini, E.; Relaño, M.; Smith, J.-D.; Tabatabaei, F.
Bibliographical reference
Astronomy and Astrophysics, Volume 591, id.A6, 24 pp.
Advertised on:
6
2016
Journal
Citations
83
Refereed citations
80
Description
Context. To compute the star formation rate (SFR) of galaxies from the
rest-frame ultraviolet (UV), it is essential to take the obscuration by
dust into account. To do so, one of the most popular methods consists in
combining the UV with the emission from the dust itself in the infrared
(IR). Yet, different studies have derived different estimators, showing
that no such hybrid estimator is truly universal. Aims: In this
paper we aim at understanding and quantifying what physical processes
fundamentally drive the variations between different hybrid estimators.
In so doing, we aim at deriving new universal UV+IR hybrid estimators to
correct the UV for dust attenuation at local and global scales, taking
the intrinsic physical properties of galaxies into account.
Methods: We use the CIGALE code to model the spatially resolved far-UV
to far-IR spectral energy distributions of eight nearby star-forming
galaxies drawn from the KINGFISH sample. This allows us to determine
their local physical properties, and in particular their UV attenuation,
average SFR, average specific SFR (sSFR), and their stellar mass. We
then examine how hybrid estimators depend on said properties.
Results: We find that hybrid UV+IR estimators strongly depend on the
stellar mass surface density (in particular at 70 μm and 100 μm)
and on the sSFR (in particular at 24 μm and the total infrared).
Consequently, the IR scaling coefficients for UV obscuration can vary by
almost an order of magnitude: from 1.55 to 13.45 at 24 μm for
instance. This result contrasts with other groups who found relatively
constant coefficients with small deviations. We exploit these variations
to construct a new class of adaptative hybrid estimators based on
observed UV to near-IR colours and near-IR luminosity densities per unit
area. We find that they can reliably be extended to entire galaxies. Conclusions: The new estimators provide better estimates of
attenuation-corrected UV emission than classical hybrid estimators
published in the literature. Taking naturally variable impact of dust
heated by old stellar populations into account, they constitute an
important step towards universal estimators.