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arXiv · 2101.11540

Multiwavelength monitoring of NGC 1275 over a decade: Evidence of a shift in synchrotron peak frequency and long-term multi-band flux increase

Sanna Gulati·Debbijoy Bhattacharya·Subir Bhattacharyya·Nilay Bhatt·C. S. Stalin·V. K. Agrawal
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Abstract

We carried out a detailed study of the temporal and broadband spectral behaviour of one of the brightest misaligned active galaxies in gamma-rays, NGC 1275 utilising 11 years of Fermi, and available Swift and AstroSat observations. Based on the cumulative flux distribution of the gamma-ray lightcurve, we identified four distinct activity states and noticed an increase in the baseline flux during the first three states. Similar nature of the increase in the average flux was also noticed in X-ray and UV bands. A large flaring activity in gamma-rays was noticed in the fourth state. The source was observed twice by AstroSat for shorter intervals (~days) during the longer observing periods (~years) state 3 and 4. During AstroSat observing periods, the source gamma-ray flux was higher than the average flux observed during longer duration states. The increase in the average baseline flux from state 1 to state 3 can be explained considering a corresponding increase of jet particle normalisation. The inverse Comptonisation of synchrotron photons explained the average X-ray and gamma-ray emission by jet electrons during the first three longer duration states. However, during the shorter duration AstroSat observing periods, a shift of the synchrotron peak frequency was noticed, and the synchrotron emission of jet electrons well explained the observed X-ray flux.

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Sanna Gulati, Debbijoy Bhattacharya, Subir Bhattacharyya, Nilay Bhatt, C. S. Stalin, V. K. Agrawal. 2021-07-10. Multiwavelength monitoring of NGC 1275 over a decade: Evidence of a shift in synchrotron peak frequency and long-term multi-band flux increase. https://doi.org/10.1093/mnras%2Fstab244

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