  The pulsar profile is characterised by two distinct emission components, the
core and the cone. The standard model of a pulsar radio emission beam
originating from dipolar magnetic fields, places the core at the centre
surrounded by concentric layers of inner and outer conal components. The core
emission is expected to have steeper spectra compared to the cones. We present
a detailed analysis of the relative differences in spectra between the core and
conal emission from a large sample of 53 pulsars over a wide frequency range
between 100 MHz and 10 GHz. The core was seen to be much steeper than the cones
particularly between 100 MHz and 1 GHz with a relative difference between the
spectral index $\Delta\alpha_{core/cone}\sim$ -1.0. In addition we also found
the spectra of the outer conal components to be steeper than the inner cone
with relative difference in the spectral index $\Delta\alpha_{in/out}\sim$
+0.5. The flattening of the spectra from the magnetic axis towards the edge of
the open field line region with increasing curvature of the field lines is a
natural outcome of the coherent curvature radiation from charged soliton
bunches, and explains the difference in spectra between the core and the cones.
In addition due to the relativistic beaming effect, the radiation is only
visible when it is directed towards the observer over a narrow angle
$\theta\leq 1/\gamma$, where $\gamma$ is the Lorentz factor of the outflowing
plasma clouds. This restricts the emission particularly from outer cones, that
are associated with field lines with larger curvature thereby making the
spectra steeper than the inner cones.

High Energy Astrophysical Phenomena