Abstract:
We present a method to map the total intrinsic reddening of a foreground extinguish-
ing medium via the analysis of spectral energy distributions (SEDs) of background
galaxies. In this pilot study, we implement this technique in two distinct regions of the
Small Magellanic Cloud (SMC) – the bar and the southern outskirts – using a com-
bination of optical and near-infrared
ugrizY JK
s
broadband imaging. We adopt the
lephare
χ
2
-minimisation SED-fitting routine and various samples of galaxies and/or
quasi-stellar objects to investigate the intrinsic reddening. We find that only when
we construct reddening maps using objects classified as galaxies with low levels of in-
trinsic reddening (i.e. ellipticals/lenticulars and early-type spirals), the resultant maps
are consistent with previous literature determinations i.e. the intrinsic reddening of
the SMC bar is higher than that in the outer environs. We employ two sets of galaxy
templates – one theoretical and one empirical – to test for template dependencies in
the resulting reddening maps and find that the theoretical templates imply system-
atically higher reddening values by up to 0.20 mag in
E
(
B
−
V
). A comparison with
previous reddening maps, based on the stellar components of the SMC, typically shows
reasonable agreement. There is, however, significant variation amongst the literature
reddening maps as to the level of intrinsic reddening associated with the bar. Thus,
it is difficult to unambiguously state that instances of significant discrepancies are
the result of appreciable levels of dust not accounted for in some literature reddening
maps or whether they reflect issues with our adopted methodology.
