| Name: | Aminabi Thekkoth |
| Affiliation: | University of Calicut,Kerala |
| Conference ID : | ASI2023_476 |
| Title : | Identifying break/curvature in the GeV spectrum of 3C 454.3. |
| Authors : | Aminabi T
Department of Physics, University of Calicut.
Dr. Sunder Sahayanathan.
Astrophysical Sciences Division, BARC, Mumbai.
Homi Bhabha National Institute, Mumbai.
Dr. C D Ravikumar
Department of Physics, University of Calicut. |
| Mode of Presentation: | Poster |
| Abstract Category : | Extragalactic Astronomy |
| Abstract : | The GeV spectral break found in the gamma ray spectrum of 3C 454.3 is a special observation feature discovered by Fermi-LAT telescope. The Fermi-LAT spectrum of 3C 454.3 does not follow a power-law function and shows a clear break at an energy of few GeVs. The interesting feature is that, the energy of break is almost stationary, ie, even when the flux changes by a factor of 20, this break shows a change by a factor of less than 2 only. While the presence of break is statistically significant, it is difficult to differentiate the spectrum between a broken power-law or a curved function such as power-law with an exponential cutoff or a log parabolic function,over a short period of time. In this context, we have analysed several gamma ray spectral energy distributions of the source corresponding to different epochs using various spectral models. We could find that the Smooth broken power-law and Log parabolic function describes the gamma ray spectrum equally well. Further the lower and higher energy spectral indices of the gamma ray SED s show a significant positive correlation. In addition to this , the difference in low and high energy spectral indices clearly deviate from the value 0.5 of classical radiative cooling. One of the possible implication will be the inherent break in the particle energy distribution together with Klein Nishina energy loss mechanism which has to be srutinized further. |
