Very high-energy gamma-ray detection and long-term multiwavelength view of the flaring blazar B2 1811+31
Articolo
Data di Pubblicazione:
2025
Abstract:
Context. Among the blazars whose emission has been detected up to very high-energy (VHE; 100 GeV < E < 100 TeV) γ rays, intermediate
synchrotron-peaked BL Lacs (IBLs) are quite rare. The IBL B2 1811+31 (z = 0.117) exhibited intense flaring activity in 2020. Detailed characterization of the source emission from radio to γ-ray energies was achieved with quasi-simultaneous observations, which led to the first-time
detection of VHE γ-ray emission from the source with the MAGIC telescopes.
Aims. In this work, we present a comprehensive multiwavelength (MWL) view of B2 1811+31, with a specific focus on the 2020 VHE flare,
employing data from MAGIC, Fermi-LAT, Swift-XRT, Swift-UVOT, and several optical and radio ground-based telescopes.
Methods. Long-term MWL data were employed to contextualize the high-state episode within the source emissions over 18 years. We investigated
the variability, cross-correlations, and classification of the source emissions during low and high states. We propose an interpretative leptonic model
for the observed radiative high state.
Results. During the 2020 flaring state, the synchrotron peak frequency shifted to higher values and reached the limit of the IBL classification.
Variability in timescales of a few hours in the high-energy (HE; 100 MeV < E < 100 GeV) γ-ray band poses an upper limit of 6×1014 δD cm on the
size of the emission region responsible for the γ-ray flare, with δD being the relativistic Doppler factor of the region. During the 2020 high state,
the average spectrum became harder in the HE γ-ray band compared to the low states. A similar behavior has been observed in X-rays. Conversely,
during different activity periods, we find harder-when-brighter trends in X-rays and a hint of softer-when-brighter trends at HE γ rays. A long-term
HE γ-ray and optical correlation indicates that the same emission regions dominate the radiative output in both ranges, whereas the evolution at 15
GHz shows no correlation with the fluxes at higher frequencies. We test one-zone and two-zone synchrotron-self-Compton models for describing
the broadband spectral energy distribution during the 2020 flaring state and investigate the self-consistency of the proposed scenario.
synchrotron-peaked BL Lacs (IBLs) are quite rare. The IBL B2 1811+31 (z = 0.117) exhibited intense flaring activity in 2020. Detailed characterization of the source emission from radio to γ-ray energies was achieved with quasi-simultaneous observations, which led to the first-time
detection of VHE γ-ray emission from the source with the MAGIC telescopes.
Aims. In this work, we present a comprehensive multiwavelength (MWL) view of B2 1811+31, with a specific focus on the 2020 VHE flare,
employing data from MAGIC, Fermi-LAT, Swift-XRT, Swift-UVOT, and several optical and radio ground-based telescopes.
Methods. Long-term MWL data were employed to contextualize the high-state episode within the source emissions over 18 years. We investigated
the variability, cross-correlations, and classification of the source emissions during low and high states. We propose an interpretative leptonic model
for the observed radiative high state.
Results. During the 2020 flaring state, the synchrotron peak frequency shifted to higher values and reached the limit of the IBL classification.
Variability in timescales of a few hours in the high-energy (HE; 100 MeV < E < 100 GeV) γ-ray band poses an upper limit of 6×1014 δD cm on the
size of the emission region responsible for the γ-ray flare, with δD being the relativistic Doppler factor of the region. During the 2020 high state,
the average spectrum became harder in the HE γ-ray band compared to the low states. A similar behavior has been observed in X-rays. Conversely,
during different activity periods, we find harder-when-brighter trends in X-rays and a hint of softer-when-brighter trends at HE γ rays. A long-term
HE γ-ray and optical correlation indicates that the same emission regions dominate the radiative output in both ranges, whereas the evolution at 15
GHz shows no correlation with the fluxes at higher frequencies. We test one-zone and two-zone synchrotron-self-Compton models for describing
the broadband spectral energy distribution during the 2020 flaring state and investigate the self-consistency of the proposed scenario.
Tipologia CRIS:
01.01 - Articolo in rivista
Elenco autori:
Abe, K.; Abe, S.; Abhir, J.; Abhishek, A.; Acciari, V. A.; Aguasca-Cabot, A.; Agudo, I.; Aniello, T.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Arcaro, C.; Asano, K.; Babić, A.; Barres De Almeida, U.; Barrio, J. A.; Barrios-Jiménez, L.; Batković, I.; Baxter, J.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Bernete, J.; Berti, A.; Besenrieder, J.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G.; Bošnjak, Ž.; Bronzini, E.; Burelli, I.; Campoy-Ordaz, A.; Carosi, A.; Carosi, R.; Carretero-Castrillo, M.; Castro-Tirado, A. J.; Cerasole, D.; Ceribella, G.; Chilingarian, A.; Cifuentes, A.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Ammando, F.; D'Amico, G.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; De Menezes, R.; Delfino, M.; Delgado, J.; Delgado Mendez, C.; Di Pierro, F.; Di Tria, R.; Di Venere, L.; Dinesh, A.; Dominis Prester, D.; Donini, A.; Dorner, D.; Doro, M.; Eisenberger, L.; Elsaesser, D.; Escudero, J.; Fariña, L.; Foffano, L.; Font, L.; Fröse, S.; Fukazawa, Y.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giesbrecht Paiva, J. G.; Giglietto, N.; Giordano, F.; Gliwny, P.; Gradetzke, T.; Grau, R.; Green, D.; Green, J. G.; Günther, P.; Hadasch, D.; Hahn, A.; Hassan, T.; Heckmann, L.; Herrera Llorente, J.; Hrupec, D.; Imazawa, R.; Israyelyan, D.; Itokawa, T.; Jiménez Martínez, I.; Jiménez Quiles, J.; Jormanainen, J.; Kankkunen, S.; Kayanoki, T.; Kerszberg, D.; Khachatryan, M.; Kluge, G. W.; Kobayashi, Y.; Konrad, J.; Kouch, P. M.; Kubo, H.; Kushida, J.; Láinez, M.; Lamastra, A.; Lindfors, E.; Lombardi, S.; Longo, F.; López-Coto, R.; López-Moya, M.; López-Oramas, A.; Loporchio, S.; Lorini, A.; Lulić, L.; Lyard, E.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Mangano, S.; Mannheim, K.; Mariotti, M.; Martínez, M.; Maruševec, P.; Mas-Aguilar, A.; Mazin, D.; Menchiari, S.; Mender, S.; Miceli, D.; Miranda, J. M.; Mirzoyan, R.; Molero González, M.; Molina, E.; Mondal, H. A.; Moralejo, A.; Nakamori, T.; Nanci, C.; Neustroev, V.; Nickel, L.; Nievas Rosillo, M.; Nigro, C.; Nikolić, L.; Nilsson, K.; Nishijima, K.; Njoh Ekoume, T.; Noda, K.; Nozaki, S.; Okumura, A.; Paiano, S.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pavletić, L.; Peresano, M.; Persic, M.; Pihet, M.; Pirola, G.; Podobnik, F.; Prada Moroni, P. G.; Prandini, E.; Principe, G.; Rhode, W.; Ribó, M.; Rico, J.; Righi, C.; Sahakyan, N.; Saito, T.; Saturni, F. G.; Schmitz, K.; Schmuckermaier, F.; Schubert, J. L.; Sciaccaluga, A.; Silvestri, G.; Sitarek, J.; Sliusar, V.; Sobczynska, D.; Stamerra, A.; Strišković, J.; Strom, D.; Strzys, M.; Suda, Y.; Tajima, H.; Takahashi, M.; Takeishi, R.; Temnikov, P.; Terauchi, K.; Terzić, T.; Teshima, M.; Tutone, A.; Ubach, S.; Van Scherpenberg, J.; Vazquez Acosta, M.; Ventura, S.; Verna, G.; Viale, I.; Vigliano, A.; Vigorito, C. F.; Vitale, V.; Vovk, I.; Walter, R.; Wersig, F.; Will, M.; Yamamoto, T.; Bartolini, C.; Bissaldi, E.; Garrappa, S.; Ankara, E.; Bader, N.; Feige, M.; Hümmer, F.; Kaplan, F.; Lorey, C.; Reinhart, D.; Schoch, K.; Steineke, R.; Marchini, A.; Fallah Ramazani, V.; Graham, M. J.; Hovatta, T.; Kiehlmann, S.; Readhead, A. C. S.; Benke, P.; Eppel, F.; Hämmerich, S.; Heßdörfer, J.; Kadler, M.; Kirchner, D.; Gokus, A.; Paraschos, G. F.; Rösch, F.; Sinapius, J.
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