Gamma-ray flaring activity of NGC 1275 in 2016-2017 measured by MAGIC
Abstract
We report on the detection of flaring activity from the Fanaroff-Riley I radio galaxy NGC 1275 in very-high-energy (VHE, E 100 GeV) gamma rays with the MAGIC telescopes. Observations were performed between 2016 September and 2017 February as part of a monitoring program. The brightest outburst with times the Crab Nebula flux above 100 GeV (C.U.) was observed during the night between 2016 December 31 and 2017 January 1 (fifty times higher than the mean previously measured in two observational campaigns between 2009 and 2011). Significant variability of the day-by-day light curve was measured, the shortest flux-doubling time-scales was found to be of min. The combined spectrum of the MAGIC data during the strongest flare state and simultaneous data from the Fermi-LAT around 2017 January 1 follows a power-law with an exponential cutoff at the energy GeV. Simultaneous optical flux density measurements in the R-band obtained with the KVA telescope are also presented and the correlation between the optical and gamma-ray emission is investigated. Due to possible internal pair-production, the fast flux variability constrains the Doppler factor to values which are inconsistent with a large viewing angle as observed in the radio band. We investigate different scenarios for the explanation of fast gamma-ray variability, namely emission from: magnetospheric gaps, relativistic blobs propagating in the jet (mini-jets) or external cloud (or star) entering the jet. We find that the only plausible model to account for the luminosities here observed would be the production of gamma rays in a magnetospheric gap around the central black hole only in the eventuality of an enhancement of the magnetic field threading the hole from its equipartition value with the gas pressure in the accretion flow.
Keywords
Cite
@article{arxiv.1806.01559,
title = {Gamma-ray flaring activity of NGC 1275 in 2016-2017 measured by MAGIC},
author = {MAGIC collaboration and S. Ansoldi and L. A. Antonelli and C. Arcaro and D. Baack and A. Babić and B. Banerjee and P. Bangale and U. Barres de Almeida and J. A. Barrio and J. Becerra González and W. Bednarek and E. Bernardini and R. Ch. Berse and A. Berti and W. Bhattacharyya and C. Bigongiari and A. Biland and O. Blanch and G. Bonnoli and R. Carosi and G. Ceribella and A. Chatterjee and S. M. Colak and P. Colin and E. Colombo and J. L. Contreras and J. Cortina and S. Covino and P. Cumani and V. D'Elia and P. Da Vela and F. Dazzi and A. De Angelis and B. De Lotto and M. Delfino and J. Delgado and F. Di Pierro and A. Domínguez and D. Dominis Prester and D. Dorner and M. Doro and S. Einecke and D. Elsaesser and V. Fallah Ramazani and A. Fattorini and A. Fernández-Barral and G. Ferrara and D. Fidalgo and L. Foffano and M. V. Fonseca and L. Font and C. Fruck and D. Galindo and S. Gallozzi and R. J. García López and M. Garczarczyk and M. Gaug and P. Giammaria and N. Godinović and D. Gora and D. Guberman and D. Hadasch and A. Hahn and T. Hassan and M. Hayashida and J. Herrera and J. Hoang and J. Hose and D. Hrupec and K. Ishio and Y. Konno and H. Kubo and J. Kushida and A. Lamastra and D. Lelas and F. Leone and E. Lindfors and S. Lombardi and F. Longo and M. López and C. Maggio and P. Majumdar and M. Makariev and G. Maneva and M. Manganaro and K. Mannheim and L. Maraschi and M. Mariotti and M. Martínez and S. Masuda and D. Mazin and K. Mielke and M. Minev and J. M. Miranda and R. Mirzoyan and A. Moralejo and V. Moreno and E. Moretti and T. Nagayoshi and V. Neustroev and A. Niedzwiecki and M. Nievas Rosillo and C. Nigro and K. Nilsson and D. Ninci and K. Nishijima and K. Noda and L. Nogués and S. Paiano and J. Palacio and D. Paneque and R. Paoletti and J. M. Paredes and G. Pedaletti and P. Peñil and M. Peresano and M. Persic and K. Pfrang and P. G. Prada Moroni and E. Prandini and I. Puljak and J. R. Garcia and I. Reichardt and W. Rhode and M. Ribó and J. Rico and C. Righi and A. Rugliancich and L. Saha and T. Saito and K. Satalecka and T. Schweizer and J. Sitarek and I. Šnidarić and D. Sobczynska and A. Stamerra and M. Strzys and T. Surić and M. Takahashi and F. Tavecchio and P. Temnikov and T. Terzić and M. Teshima and N. Torres-Albà and S. Tsujimoto and G. Vanzo and M. Vazquez Acosta and I. Vovk and J. E. Ward and M. Will and D. Zarić and D. Glawion and L. O. Takalo and J. Jormanainen},
journal= {arXiv preprint arXiv:1806.01559},
year = {2018}
}
Comments
accepted for publications in Astronomy and Astrophysics