The contribution of the Unresolved Extragalactic Radio Sources to the Brightness Temperature of the sky

Understand

The contribution of the Unresolved Extragalactic Radio Sources to the diffuse brightness of the sky was evaluated using the source number - flux measurements available in literature.

• We first optimized the fitting function of the data based on number counts distribution.
• We then computed the brightness temperature at various frequencies from 151 MHz to 8440 MHz and derived its spectral dependence.
• As expected the frequency dependence can be described by a power law with a spectral index $\gamma \simeq -2.7$, in agreement with the flux emitted by the {\it steep spectrum} sources.