The extreme HBL behaviour of Markarian 501 during 2012
Abstract
A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of 0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was 3 CU, and the peak of the high-energy spectral component was found to be at 2 TeV. This study reports very hard X-ray spectra, and the hardest VHE spectra measured to date for Mrk 501. The fractional variability was found to increase with energy, with the highest variability occurring at VHE, and a significant correlation between the X-ray and VHE bands. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency- peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The one-zone synchrotron self-Compton (SSC) scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behaviour seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays.
Keywords
Cite
@article{arxiv.1808.04300,
title = {The extreme HBL behaviour of Markarian 501 during 2012},
author = {M. L. Ahnen and S. Ansoldi and L. A. Antonelli and C. Arcaro 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 A. Berti and W. Bhattacharyya and O. Blanch and G. Bonnoli and R. Carosi and A. Carosi 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 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 M. Doert and A. Domínguez and D. Dominis Prester and M. Doro and D. Eisenacher Glawion and M. Engelkemeier and V. Fallah Ramazani and A. Fernández-Barral and D. Fidalgo and M. V. Fonseca and L. Font and C. Fruck and D. Galindo 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. Hose and D. Hrupec and K. Ishio and Y. Konno and H. Kubo and J. Kushida and D. Kuveždić and D. Lelas 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 L. Maraschi and M. Mariotti and M. Martínez and D. Mazin and U. Menzel 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 M. Peresano and L. Perri and M. Persic and P. G. Prada Moroni and E. Prandini and I. Puljak and J. R. Garcia and I. Reichardt and M. Ribó and J. Rico and C. Righi and A. Rugliancich and T. Saito and K. Satalecka and S. Schroeder and T. Schweizer and S. N. Shore and J. Sitarek and I. Šnidarić and D. Sobczynska and A. Stamerra and M. Strzys and T. Surić and L. Takalo and F. Tavecchio and P. Temnikov and T. Terzić and M. Teshima and N. Torres-Albà and A. Treves and S. Tsujimoto and G. Vanzo and M. Vazquez Acosta and I. Vovk and J. E. Ward and M. Will and D. Zarić and A. Arbet-Engels and D. Baack and M. Balbo and A. Biland and M. Blank and T. Bretz and K. Bruegge and M. Bulinski and J. Buss and A. Dmytriiev and D. Dorner and S. Einecke and D. Elsaesser and T. Herbst and D. Hildebrand and L. Kortmann and L. Linhoff and M. Mahlke and K. Mannheim and S. A. Mueller and D. Neise and A. Neronov and M. Noethe and J. Oberkirch and A. Paravac and W. Rhode and B. Schleicher and F. Schulz and K. Sedlaczek and A. Shukla and V. Sliusar and R. Walter and A. Archer and W. Benbow and R. Bird and R. Brose and J. H. Buckley and V. Bugaev and J. L. Christiansen and W. Cui and M. K. Daniel and A. Falcone and Q. Feng and J. P. Finley and G. H. Gillanders and O. Gueta and D. Hanna and O. Hervet and J. Holder and G. Hughes and M. Hütten and T. B. Humensky and C. A. Johnson and P. Kaaret and P. Kar and N. Kelley-Hoskins and M. Kertzman and D. Kieda and M. Krause and F. Krennrich and S. Kumar and M. J. Lang and T. T. Y. Lin and G. Maier and S. McArthur and P. Moriarty and R. Mukherjee and S. O'Brien and R. A. Ong and A. N. Otte and N. Park and A. Petrashyk and A. Pichel and M. Pohl and J. Quinn and K. Ragan and P. T. Reynolds and G. T. Richards and E. Roache and A. C. Rovero and C. Rulten and I. Sadeh and M. Santander and G. H. Sembroski and K. Shahinyan and I. Sushch and J. Tyler and S. P. Wakely and A. Weinstein and R. M. Wells and P. Wilcox and A. Wilhel and D. A. Williams and T. J Williamson and B. Zitzer and M. Perri and F. Verrecchia and C. Leto and M. Villata and C. M. Raiteri and S. G. Jorstad and V. M. Larionov and D. A. Blinov and T. S. Grishina and E. N. Kopatskaya and E. G. Larionova and A. A. Nikiforova and D. A. Morozova and Yu. V. Troitskaya and I. S. Troitsky and O. M. Kurtanidze and M. G. Nikolashvili and S. O. Kurtanidze and G. N. Kimeridze and R. A. Chigladze and A. Strigachev and A. C. Sadun and J. W. Moody and W. P. Chen and H. C. Lin and J. A. Acosta-Pulido and M. J. Arévalo and M. I. Carnerero and P. A. González-Morales and A. Manilla-Robles and H. Jermak and I. Steele and C. Mundel and E. Benítez and D. Hiriart and P. S. Smith and W. Max-Moerbeck and A. C. S. Readhead and J. L. Richards and T. Hovatta and A. Lähteenmäki and M. Tornikoski and J. Tammi and M. Georganopoulos and M. G. Baring},
journal= {arXiv preprint arXiv:1808.04300},
year = {2020}
}
Comments
25 pages, 9 figures, accepted for publication in A&A. Corresponding authors: Gareth Hughes ([email protected]), David Paneque ([email protected]), Amit Shukla ([email protected])