We use the Expanded Very Large Array to image radio continuum emission from local luminous and ultraluminous infrared galaxies ( LIRGs and ULIRGs ) in 1 GHz windows centered at 4.7 , 7.2 , 29 , and 36 GHz .
This allows us to probe the integrated radio spectral energy distribution ( SED ) of the most energetic galaxies in the local universe .
The 4–8 GHz flux densities agree well with previous measurements .
They yield spectral indices \alpha \approx - 0.67 ( where F _ { \nu } \propto \nu ^ { \alpha } ) with \pm 0.15 ( 1 \sigma ) scatter , typical of nonthermal ( synchrotron ) emission from star-forming galaxies .
The contrast of our 4–8 GHz data with literature 1.5 and 8.4 GHz flux densities gives further evidence for curvature of the radio SED of U/LIRGs .
The SED appears flatter near \sim 1 GHz than near \sim 6 GHz , suggesting significant optical depth effects at the lower frequencies .
The high frequency ( 28–37 GHz ) flux densities are low compared to extrapolations from the 4–8 GHz data .
We confirm and extend to higher frequency a previously observed deficit of high frequency radio emission for luminous starburst galaxies .