Call
In astronomy, the spectral index of a source is a measure of the dependence of radiative flux density on frequency. Given frequency ν {\displaystyle \nu } and radiative flux density S ν {\displaystyle S_{\nu }} , the spectral index α {\displaystyle \alpha } is given implicitly by
Note that if flux does not follow a power law in frequency, the spectral index itself is a function of frequency. Rearranging the above, we see that the spectral index is given by
Clearly the power law can only apply over a certain range of frequency because otherwise the integral over all frequencies would be infinite.
Spectral index is also sometimes defined in terms of wavelength λ {\displaystyle \lambda }. In this case, the spectral index α {\displaystyle \alpha } is given implicitly by
Talk Doctor Online in Bissoy App