ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: by a characteristic timescale, t esc . The evolution of the particle number density, , in the CR can then be conveniently described by the kinetic equation (Kardashev 1962 )where is the energy loss rate due to synchrotron and SSC processes. Assuming a power law dependence of escape timescale with energy , a semianalytical solution of Equation ( 8 ) can be attained when the loss processes are confined within the Thomson regime (Atoyan Aharonian 1999 ). However, detection of the source at VHE energies suggests that the Thomson scattering approximation of SSC process may not be valid and one needs to incorporate Klein–Nishina correction in the cross-section (Tavecchio et al. 1998 ). Hence, we numerically solve Equation ( 8 ) using a fully implicit finite difference scheme (Chang Cooper 1970 ; Chiaberge Ghisellini 1999 ), while incorporating the exact Klein–Nishina cross-section for IC scattering (Blumenthal Gould 1970 ). The case (no escape) gives rise to a BPL with the break occurring at the energy where the observation time is equal to the cooling timescale of the particle, while for the case (constant t esc ), a steady state BPL particle distribution is eventually attained where the break corresponds to the particle energy at which the escape timescale equates to its cooling timescale. However, in these cases, the spectral transition at the break energy is too sharp to reproduce the observed SED, and a gradual transition can be achieved by considering . We found that the smooth spectral curvature demanded by the observation can be attained by fixing . In Figure 7 , we show the resultant model SED corresponding to (blue line) and , along with the observed fluxes for the state s3. The underlying particle distribution corresponding to these values of ξ is shown in Figure 8 . Figure 7. Model curves obtained by changing the energy dependence of the escape timescale for the state s3. The blue line is obtained for a energy independent escape (), and fails to reproduce the observed spectrum. The best match between the data and the model is obtained for and is represented by the solid green line. The magnetic field B is assumed to be 0.4 G and the Doppler factor . The injected particle spectrum is a power of index 2.1. Figure 8. Underlying particle spectra for the model curves shown in Figure 7 . The dashed blue line is obtained for an energy independent escape ( which fails to reproduce the observed SED), and the solid black line corresponds to the particle spectrum that best models the observed SED (). Alternate to this interpretation, a smooth curvature in the particle distribution can also be a result of time averaging of an evolving particle distribution. For instance, an episodic injection of a power-law particle distribution into CR can cause the high energy cutoff to shift toward lower energy with time, which will be reflected as a smooth curvature at high energy in the time averaged spectrum. Also, an episodic injection with an