The radio-FIR correlation in the Milky way

We investigate the scale on which the correlation arises between the 843MHz radio and the 60 μm far-infrared (FIR) emission from star forming regions in the Milky way. The correlation, which exists on the smallest scales investigated (down to ≈4pc), becomes noticeably tight on fields of size 30′, corresponding to physical scales of ≈20-50pc. The FIR to radio flux ratio on this scale is consistent with the radio emission being dominated by thermal emission. We also investigate the location dependence of q _mean, a parameter measuring the mean FIR to radio flux ratio, of a sample of star forming regions. We show that q_mean displays a modest dependence on galactic latitude. If this is interpreted as a dependence on the intensity of star formation activity, the result is consistent with studies of the Large Magellanic Cloud (LMC) and other nearby galaxies that show elevated values for q in regions of enhanced star formation.