Correlations between the radio continuum , infrared and CO emission are known to exist for several types of galaxies and across several orders of magnitude .
However , the low-mass , low-luminosity and low-metallicity regime of these correlations is not well known .
A sample of metal-rich and metal-poor dwarf galaxies from the literature has been assembled to explore this extreme regime .
The results demonstrate that the properties of dwarf galaxies are not simple extensions of those of more massive galaxies ; the different correlations reflect different star-forming conditions and different coupling between the star formation and the various quantities .
It is found that dwarfs show increasingly weaker CO and infrared emission for their luminosity , as expected for galaxies with a low dust content , slower reaction rates , and a hard ionizing radiation field .
In the higher-luminosity dwarf regime ( L _ { 1.4 GHz } \gtrsim 10 ^ { 27 } W , where L _ { 1.4 GHz } \simeq 10 ^ { 29 } W for a Milky Way star formation rate of \simeq 1 M _ { \odot } yr ^ { -1 } ) , the total and non-thermal radio continuum emission appear to adequately trace the star formation rate .
A breakdown of the dependence of the ( H \alpha -based ) thermal , non-thermal , and , hence , total radio continuum emission on star formation rate occurs below L _ { 1.4 GHz } \simeq 10 ^ { 27 } W , resulting in a steepening or downturn of the relations at extreme low luminosity .
Below L _ { FIR } \simeq 10 ^ { 36 } W \simeq 3 \times 10 ^ { 9 } L _ { \odot } , the infrared emission ceases to adequately trace the star formation rate .
A lack of a correlation between the magnetic field strength and the star formation rate in low star formation rate dwarfs suggests a breakdown of the equipartition assumption .
As extremely metal-poor dwarfs mostly populate the low star formation rate and low luminosity regime , they stand out in their infrared , radio continuum and CO properties .