Low-metallicity galaxies exhibit different properties of the interstellar medium ( ISM ) compared to nearby spiral galaxies .
Obtaining a resolved inventory of the various gas and dust components of massive star forming regions and diffuse ISM is necessary to understand how those differences are driven .
We present a study of the infrared/submillimeter ( submm ) emission of the massive star forming complex N158-N159-N160 located in the Large Magellanic Cloud .
Combining observations from the Spitzer  Space Telescope ( 3.6-70 \mu m ) , the Herschel  Space Observatory ( 100-500 \mu m ) and LABOCA ( on APEX , 870 \mu m ) allows us to work at the best angular resolution available now for an extragalactic source ( a few parsecs for the LMC ) .
We observe a remarkably good correlation between the Herschel  SPIRE and LABOCA emission and resolve the low surface brightnesses emission .
We use the Spitzer  and Herschel  data to perform a resolved Spectral Energy Distribution ( SED ) modelling of the complex .
Using modified blackbodies , we derive an average “ effective ” emissivity index of the cold dust component \beta _ { c } of 1.47 across the complex .
If \beta _ { c } is fixed to 1.5 , we find an average temperature of \sim 27K ( maximum of \sim 32K in N160 ) .
We also apply the SED modelling technique ( using amorphous carbon to model carbon dust ) to derive maps of the star formation rate , the grain temperature , the mean starlight intensity , the fraction of Polycyclic Aromatic Hydrocarbons ( PAH ) or the dust mass surface density of the region .
We observe that the PAH fraction strongly decreases in the H ii regions we study .
This decrease coincides with peaks in the mean radiation field intensity map .
The dust surface densities follow the far-infrared distribution , with a total dust mass of 2.1 \times 10 ^ { 4 } M _ { \odot } Â ( 2.8 times less than if carbon dust was modelled by standard graphite grains ) in the resolved elements we model .
We also find a non-negligible amount of dust in the region called “ N159 South ” , a molecular cloud that does not show massive star formation .
We also investigate the drivers of the Herschel /PACS and SPIRE submm colours and find that the submm ratios correlate strongly with the radiation field intensity and with the near and mid-IR surface brightnesses equally well .
Comparing our dust map to H i and CO observations in N159 , we then investigate variations in the gas-to-dust mass ratio ( G/D ) and the CO-to-H _ { 2 } conversion factor X _ { CO } .
A mean value of G/D \sim 356 is derived when using X _ { CO } = 7 \times 10 ^ { 20 } H _ { 2 } cm ^ { -2 } ( K km s ^ { -1 } ) ^ { -1 } ( ) .
If a constant G/D across N159 is assumed , we derive a X _ { CO } conversion factor of 5.4 \times 10 ^ { 20 } H _ { 2 } cm ^ { -2 } ( K km s ^ { -1 } ) ^ { -1 } .
We finally model individual regions to analyse variations in the SED shape across the complex and the 870 \mu m emission in more details .
No measurable submm excess emission at 870 \mu m seems to be detected in these regions .