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==> In this proposal, more time is being requested for TTHUAN.SBS_0335
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Following our observation of SBS 0335-052 in the mid-infrared range we
propose here to extend the infrared coverage of this exceptional
object. This is motivated by the fact that SBS 0335-052, one of the
most metal-deficient galaxy known, is much brighter in the infrared
than expected from its star-forming properties (a factor of 6 in the
LW10 band and we extrapolate at least a factor of 3 for the full
infrared range). Furthermore, the spectrum appears to require
contribution from PAH emission, i.e. Carbon dust, a very unexpected
dust component in a low metallicity object. The observations we
propose to perform here are twofold:
A CVF scan on the 9-16 microns that will:
- assess the contribution of Carbon based dust
- reveal the shape of the continuum and allow comparison to that
observed in more metal-rich objects
- reveal the presence of a deep silicate absorption, an expected
feature if the excess infrared is due to embedded HII regions.
PHT measurements at 25, 50, 60, 100, 120, 160 and 200 mic. The aim is
to characterize with high details the infrared output of SBS in order
to determine the origin of the excess emission, the amount of dust
that is already present in the galaxy and the exact amount of
star-formation generated energy that is released in the infrared.
These observations would make of SBS 0335-052 one of the best studied
analog to primordial galaxies that are now being detected at high
redshift. The possibility that even very young galaxies might
efficiently hide a substantial fraction of their star formation, as
SBS 0335-052 appears to do, would have profound impacts on how we
derive the star formation rate at high redshift.