Spatially resolved dust emission of extremely metal poor galaxies
  We present infrared (IR) spectral energy distributions (SEDs) of individual
star-forming regions in four extremely metal poor (EMP) galaxies with
metallicity Z around Zsun/10 as observed by the Herschel Space Observatory.
With the good wavelength coverage of the SED, it is found that these EMP
star-forming regions show distinct SED shapes as compared to those of grand
design Spirals and higher metallicity dwarfs: they have on average much higher
f70um/f160um ratios at a given f160um/f250um ratio; single modified black-body
(MBB) fittings to the SED at \lambda >= 100 um still reveal higher dust
temperatures and lower emissivity indices compared to that of Spirals, while
two MBB fittings to the full SED with a fixed emissivity index (beta = 2) show
that even at 100 um about half of the emission comes from warm (50 K) dust, in
contrast to the cold (~20 K) dust component. Our spatially resolved images
further reveal that the far-IR colors including f70um/f160um, f160um/f250um and
f250um/f350um are all related to the surface densities of young stars as traced
by far-UV, 24 um and SFRs, but not to the stellar mass surface densities. This
suggests that the dust emitting at wavelengths from 70 um to 350 um is
primarily heated by radiation from young stars.
