Characterization of Markarian 421 during its most violent year: Multiwavelength variability and correlations

Aims. Mrk 421 was in its most active state around early 2010, which led to the highest TeV gamma-ray flux ever recorded from any active galactic nuclei (AGN). We aim to characterize the multiwavelength behavior during this exceptional year for Mrk 421, and evaluate whether it is consistent with the picture derived with data from other less exceptional years. Methods. We investigated the period from November 5, 2009, (MJD 55140) until July 3, 2010, (MJD 55380) with extensive coverage from very-high-energy (VHE; E > 100 GeV) gamma rays to radio with MAGIC, VERITAS, Fermi -LAT, RXTE , Swift , GASP-WEBT, VLBA, and a variety of additional optical and radio telescopes. We characterized the variability by deriving fractional variabilities as well as power spectral densities (PSDs). In addition, we investigated images of the jet taken with VLBA and the correlation behavior among different energy bands. Results. Mrk 421 was in widely different states of activity throughout the campaign, ranging from a low-emission state to its highest VHE flux ever recorded. We find the strongest variability in X-rays and VHE gamma rays, and PSDs compatible with power-law functions with indices around 1.5. We observe strong correlations between X-rays and VHE gamma rays at zero time lag with varying characteristics depending on the exact energy band. We also report a marginally significant (∼3 σ ) positive correlation between high-energy (HE; E > 100 MeV) gamma rays and the ultraviolet band. We detected marginally significant (∼3 σ ) correlations between the HE and VHE gamma rays, and between HE gamma rays and the X-ray, that disappear when the large flare in February 2010 is excluded from the correlation study, hence indicating the exceptionality of this flaring event in comparison with the rest of the campaign. The 2010 violent activity of Mrk 421 also yielded the first ejection of features in the VLBA images of the jet of Mrk 421. Yet the large uncertainties in the ejection times of these unprecedented radio features prevent us from firmly associating them to the specific flares recorded during the 2010 campaign. We also show that the collected multi-instrument data are consistent with a scenario where the emission is dominated by two regions, a compact and extended zone, which could be considered as a simplified implementation of an energy-stratified jet as suggested by recent IXPE observations.

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Journal
Astronomy and Astrophysics
Published
2025-01-09
DOI
https://doi.org/10.1051/0004-6361/202451624
Citations
7
Primary Topic
Astrophysics and Cosmic Phenomena
Type
article
Field-Weighted Citation Impact
13.09
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Characterization of Markarian 421 during its most violent year: Multiwavelength variability and correlations

A. Hahn, R. Grau, Patrick Günther, I. Vovk et al.
7 citations
Astronomy and Astrophysics
Astrophysics and Cosmic Phenomena
13.09
article

Characterization of Markarian 421 during its most violent year: Multiwavelength variability and correlations

A. Hahn, R. Grau, Patrick Günther, I. Vovk, F. Leone, D. Green, K. Nishijima, D. Sobczyńska, O. Blanch, K. Schmidt, Irene Burelli, F. Schmuckermaier, D. Strom, M. Persic, Marine Pihet, Paweł Gliwny, T. Njoh Ekoume, S. Mender, D. Baack, E. Molina, Francesco Gabriele Saturni, Alvaro Mas-Aguilar, Juliane van Scherpenberg, S. Abe, P. Temnikov, H. Tajima, J.L Schubert, M. Mariotti, M. Takahashi, C. Delgado Mendez, Jarred Gershon Green, Daniel Morcuende, M. Delfino, J. Abhir, Laura Eisenberger, F. Di Pierro, F. Dazzi, D. Kerszberg, M. Gaug, U. Barres de Almeida, Sargis Gasparyan, Pouya M. Kouch, E. Bernardini, M. Tornikoski, A. López-Oramas, F. Podobnik, A. Biland, T. Saito, D. Cerasole, J. A. Barrio, R. Walter, Stefan Fröse, A. E. Wehrle, A. Bautista, A. De Angelis, J. Otero-Santos, I. Batković, G. Principe, E. Do Souto Espiñeira, W. Max-Moerbeck, Giacomo D’Amico, M. Perri, M. Carretero-Castrillo, L. Font, M. Ribó, C. Vigorito, F. Tavecchio, H. Kubo, S. Paiano, T. Kayanoki, N. Sahakyan, Y. Fukazawa, E. Prandini, Sofia Ventura, J. M. Paredes, I. Agudo, T. Terzić, Antonio Tutone, V. A. Acciari, C. Righi, G. Verna, Ryuji Takeishi, Davide Miceli, T. Nakamori, K. Noda, V. Neustroev, N. Godinović, C. Nanci, Santiago Ubach, A. Lorini, J. Delgado, M. Garczarczyk, G. Bonnoli, L. Foffano, I. Viale, A. Stamerra, H. A. Mondal, M. Doro, D. Mazin, K. Terauchi, A. Babić, María Martínez-Chicharro, D. Dorner, M. Will, S. Lombardi, Raniere de Menezes, M. Makariev, J. Escudero, Gabriella Silvestri, J. Cortina, J. Jormanainen, T. Hassan, W. Rhode, Tokonatsu Yamamoto, S. Covino, Dario Hrupec, Arnau Aguasca-Cabot, G. Pirola, C. Bigongiari, G. Ceribella, C. Arcaro, Gert Werner Kluge, D. Elsäesser, Ryo Imazawa, S. Loporchio, A. C. S. Readhead, V. Vitale, Mark Gurwell, W. Bednarek, Alan P. Marscher, M. Manganaro, J. G. Giesbrecht Paiva, J. Besenrieder, Magda Gonzalez, A. Sciaccaluga, A. Cifuentes, L. Heckmann, T. Aniello, Yating Chai, Irene Jiménez Martínez, S. Ansoldi, J. M. Miranda, C. Leto, A. Lähteenmäki, F. Verrecchia, Lukas Nickel, A. Okumura, J. Kushida, Stefano Menchiari, M. F. Aller, Alice Donini, M. Peresano, R. Carosi, L. A. Antonelli, Tjark Miener, L. Fari na, K. Mannheim, J. Baxter, K. Asano, F. D'Ammando, J. Bernete, E. Bronzini, A. Campoy-Ordaz, T. Gradetzke, S. Kankkunen, J. Becerra González, Y. Suda, Marcos López, S. Nozaki, Satoshi Fukami, Kazuma Ishio, A.J. Castro-Tirado, N. Giglietto, S. Mangano, P. Majumdar, R. J. Garcı́a López, A. Abhishek, R. Di Tria, J. Sitarek, J. Herrera Llorente, K. Nilsson, P. Da Vela, R. Mirzoyan, G. Maneva, Stefano Truzzi, M. Lainez, J. Strišković, R. López-Coto, J. Rico, T. Schweizer, D. Paneque, A. Moralejo, B. De Lotto, E. Lindfors, S.G. Jorstad, A. Fattorini, V. D’Elia, A. Lamastra, C Nigro, Ž. Bošnjak, L. Di Venere, A. Arbet Engels, M. Teshima, K. Abe, F. Longo, A. Berti, F. Giordano, D. Hadasch, P.G. Prada Moroni, R. Paoletti, E. Colombo, M. Martínez, J.L. Contreras, F. Wersig, L. Nikolić
article en
7 citations

Abstract

Aims. Mrk 421 was in its most active state around early 2010, which led to the highest TeV gamma-ray flux ever recorded from any active galactic nuclei (AGN). We aim to characterize the multiwavelength behavior during this exceptional year for Mrk 421, and evaluate whether it is consistent with the picture derived with data from other less exceptional years. Methods. We investigated the period from November 5, 2009, (MJD 55140) until July 3, 2010, (MJD 55380) with extensive coverage from very-high-energy (VHE; E > 100 GeV) gamma rays to radio with MAGIC, VERITAS, Fermi -LAT, RXTE , Swift , GASP-WEBT, VLBA, and a variety of additional optical and radio telescopes. We characterized the variability by deriving fractional variabilities as well as power spectral densities (PSDs). In addition, we investigated images of the jet taken with VLBA and the correlation behavior among different energy bands. Results. Mrk 421 was in widely different states of activity throughout the campaign, ranging from a low-emission state to its highest VHE flux ever recorded. We find the strongest variability in X-rays and VHE gamma rays, and PSDs compatible with power-law functions with indices around 1.5. We observe strong correlations between X-rays and VHE gamma rays at zero time lag with varying characteristics depending on the exact energy band. We also report a marginally significant (∼3 σ ) positive correlation between high-energy (HE; E > 100 MeV) gamma rays and the ultraviolet band. We detected marginally significant (∼3 σ ) correlations between the HE and VHE gamma rays, and between HE gamma rays and the X-ray, that disappear when the large flare in February 2010 is excluded from the correlation study, hence indicating the exceptionality of this flaring event in comparison with the rest of the campaign. The 2010 violent activity of Mrk 421 also yielded the first ejection of features in the VLBA images of the jet of Mrk 421. Yet the large uncertainties in the ejection times of these unprecedented radio features prevent us from firmly associating them to the specific flares recorded during the 2010 campaign. We also show that the collected multi-instrument data are consistent with a scenario where the emission is dominated by two regions, a compact and extended zone, which could be considered as a simplified implementation of an energy-stratified jet as suggested by recent IXPE observations.

Astronomy and AstrophysicsVol. 694
University of Siena (IT), University of Pisa (IT), Boston University (US), Yamagata University (JP), Hiroshima University (JP), University of Geneva (CH), Obayashi (Japan) (JP), Universidad Complutense de Madrid (ES), California Institute of Technology (US), Universitat Autònoma de Barcelona (ES), University of Udine (IT), Space Science Institute (US), Tokai University (JP), University of Padua (IT), University of Trieste (IT), University of Rijeka (HR), University of Turku (FI), Universidad de La Laguna (ES), Chiba University (JP), Konan University (JP), Saha Institute of Nuclear Physics (IN), University of Zagreb (HR), Turku Centre for Computer Science (FI), OsloMet – Oslo Metropolitan University (NO), University of Oslo (NO), Institute for High Energy Physics (ES), Homi Bhabha National Institute (IN), TU Dortmund University (DE), Kyoto University (JP), Bulgarian Academy of Sciences (BG), University of Würzburg (DE), University of Michigan (US), Astronomical Observatory of Rome (IT), Agenzia Spaziale Italiana (IT), Deutsches Elektronen-Synchrotron DESY (DE), Nicolaus Copernicus University (PL), University of Łódź (PL), ETH Zurich (CH), Max Planck Institute for Physics (DE), Istituto Nazionale di Fisica Nucleare, Sezione di Torino (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Padova (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Bari (IT), Istituto di Radioastronomia di Bologna (IT), Finnish Youth Research Society (FI), International Center for Relativistic Astrophysics (IT), Center for Astrophysics Harvard & Smithsonian (US), Centro Brasileiro de Pesquisas Físicas (BR), Instituto de Astrofísica de Canarias (ES), International Center for Relativistic Astrophysics Network (AM), Port d'Informació Científica (ES), Istituto Nazionale di Fisica Nucleare, Sezione di Roma I (IT), Instituto de Astrofísica de Andalucía (ES), Istituto Nazionale di Fisica Nucleare, Sezione di Pisa (IT), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (ES), University of Bergen (NO), University of Osijek (HR), University of Turin (IT), Nagoya University (JP), Polytechnic University of Bari (IT), University of Chile (CL), Universitat de Barcelona (ES), The University of Tokyo (JP), National Institute for Astrophysics (IT), Foundation for Research and Technology Hellas (GR), University of Split (HR), University of Oulu (FI), Aalto University (FI)
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