Extreme HBL behavior of Markarian 501 during 2012

M. L. Ahnen, S. Ansoldi, L. A. Antonelli, C. Arcaro, A. Babić, B. Banerjee, P. Bangale, U. Barresde Almeida, J. A. Barrio, J. Becerragonzález, W. Bednarek, E. Bernardini, A. Berti, W. Bhattacharyya, O. Blanch, G. Bonnoli, R. Carosi, A. Carosi, A. Chatterjee, S. M. ColakP. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, P. Cumani, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, F. Di Ierro, M. Doert, A. Domínguez, D. Dominis Prester, M. Doro, D. Eisenacher Lawion, M. Engelkemeier, V. Fallah Ramazani, A. Fernández-Barral, D. Fidalgo, M. V. Fonseca, L. Font, C. Fruck, D. Galindo, R. J. García López, M. Garczarczyk, M. Gaug, P. Giammaria, N. Godinović, D. Gora, D. Guberman, D. Hadasch, A. Hahn, T. Hassan, M. Hayashida, J. Herrera, J. Hose, D. Hrupec, K. Ishio, Y. Konno, H. Kubo, J. Kushida, D. Kuve Dić, D. Lelas, E. Lindfors, S. Lombardi, F. Longo, M. López, C. Maggio, P. Majumdar, M. Makariev, G. Maneva, M. Manganaro, L. Maraschi, M. Mariotti, M. Martínez, D. Mazin, U. Menzel, M. Minev, J. M. Miranda, R. Mirzoyan, A. Moralejo, V. Moreno, E. Moretti, T. Nagayoshi, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, C. Nigro, K. Nilsson, D. Ninci, K. Nishijima, K. Noda, L. Nogués, S. Paiano, J. Palacio, D. Paneque, R. Paoletti, J. M. Paredes, G. Pedaletti, M. Peresano, L. Perri, M. Persic, P. G. Prada Moroni, E. Prandini, I. Puljak, J. R. Garcia, I. Reichardt, M. Ribó, J. Rico, C. Righi, A. Rugliancich, T. Saito, K. Satalecka, S. Schroeder, T. Schweizer, S. N. Shore, J. Sitarek, I. Šnidarić, D. Sobczynska, A. Stamerra, M. Strzys, T. Surić, L. Takalo, F. Tavecchio, P. Temnikov, T. Terzić, M. Teshima, N. Torres-Albà, A. Treves, S. Tsujimoto, G. Vanzo, M. Vazquez Acosta, I. Vovk, J. E. Ward, M. Will, D. Zarić, A. Arbet-Engels, D. Baack, M. Balbo, A. Biland, M. Blank, T. Bretz, K. Bruegge, M. Bulinski, J. Buss, A. Dmytriiev, D. Dorner, S. Einecke, D. Elsaesser, T. Herbst, D. Hildebrand, L. Kortmann, L. Linhoff, M. Mahlke, K. Mannheim, S. A. Mueller, D. Neise, A. Neronov, M. Noethe, J. Oberkirch, A. Paravac, W. Rhode, B. Schleicher, F. Schulz, K. Sedlaczek, A. Shukla, V. Sliusar, R. Walter, A. Archer, W. Benbow, R. Bird, R. Brose, J. H. Buckley, V. Bugaev, J. L. Christiansen, W. Cui, M. K. Daniel, A. Falcone, Q. Feng, J. P. Finley, G. H. Gillanders, O. Gueta, D. Hanna, O. Hervet, J. Holder, G. Hughes, M. Hütten, T. B. Humensky, C. A. Johnson, P. Kaaret, P. Kar, N. Kelley-Hoskins, M. Kertzman, D. Kieda, M. Krause, F. Krennrich, S. Kumar, M. J. Lang, T. T.Y. Lin, G. Maier, S. McArthur, P. Moriarty, R. Mukherjee, S. O'Brien, R. A. Ong, A. N. Otte, N. Park, A. Petrashyk, A. Pichel, M. Pohl, J. Quinn, K. Ragan, P. T. Reynolds, G. T. Richards, E. Roache, A. C. Rovero, C. Rulten, I. Sadeh, M. Santander, G. H. Sembroski, K. Shahinyan, I. Sushch, J. Tyler, S. P. Wakely, A. Weinstein, R. M. Wells, P. Wilcox, A. Wilhel, D. A. Williams, T. J Williamson, B. Zitzer, M. Perri, F. Verrecchia, C. Leto, M. Villata, C. M. Raiteri, S. G. Jorstad, V. M. Larionov, D. A. Blinov, T. S. Grishina, E. N. Kopatskaya, E. G. Larionova, A. A. Nikiforova, D. A. Morozova, Yu V. Troitskaya, I. S. Troitsky, O. M. Kurtanidze, M. G. Nikolashvili, S. O. Kurtanidze, G. N. Kimeridze, R. A. Chigladze, A. Strigachev, A. C. Sadun, J. W. Moody, W. P. Chen, H. C. Lin, J. A. Acosta-Pulido, M. J. Arévalo, M. I. Carnerero, P. A. González-Morales, A. Manilla-Robles, H. Jermak, I. Steele, C. Mundell, E. Benítez, D. Hiriart, P. S. Smith, W. Max-Moerbeck, A. C.S. Readhead, J. L. Richards, T. Hovatta, A. Lähteenmäki, M. Tornikoski, J. Tammi, M. Georganopoulos, M. G. Baring

Research output: Contribution to journalArticle

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Abstract

Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign 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. Results. 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. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices < 2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance < 3σ) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. 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 data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone 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 behavior 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.

Original languageEnglish (US)
Article numberA181
JournalAstronomy and Astrophysics
Volume620
DOIs
StatePublished - Dec 1 2018

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energy
gamma rays
x rays
synchrotrons
spectral energy distribution
energy bands
energy spectra
Global Air Sampling Program
telescopes
energy flux
broadband
Crab nebula
high energy electrons
flares
electron
spacecraft
flux density
temporal evolution
electron energy
injection

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Arcaro, C., Babić, A., Banerjee, B., ... Baring, M. G. (2018). Extreme HBL behavior of Markarian 501 during 2012. Astronomy and Astrophysics, 620, [A181]. https://doi.org/10.1051/0004-6361/201833704
Ahnen, M. L. ; Ansoldi, S. ; Antonelli, L. A. ; Arcaro, C. ; Babić, A. ; Banerjee, B. ; Bangale, P. ; Barresde Almeida, U. ; Barrio, J. A. ; Becerragonzález, J. ; Bednarek, W. ; Bernardini, E. ; Berti, A. ; Bhattacharyya, W. ; Blanch, O. ; Bonnoli, G. ; Carosi, R. ; Carosi, A. ; Chatterjee, A. ; Colak, S. M. ; Colin, P. ; Colombo, E. ; Contreras, J. L. ; Cortina, J. ; Covino, S. ; Cumani, P. ; Da Vela, P. ; Dazzi, F. ; De Angelis, A. ; De Lotto, B. ; Delfino, M. ; Delgado, J. ; Di Ierro, F. ; Doert, M. ; Domínguez, A. ; Dominis Prester, D. ; Doro, M. ; Eisenacher Lawion, D. ; Engelkemeier, M. ; Fallah Ramazani, V. ; Fernández-Barral, A. ; Fidalgo, D. ; Fonseca, M. V. ; Font, L. ; Fruck, C. ; Galindo, D. ; García López, R. J. ; Garczarczyk, M. ; Gaug, M. ; Giammaria, P. ; Godinović, N. ; Gora, D. ; Guberman, D. ; Hadasch, D. ; Hahn, A. ; Hassan, T. ; Hayashida, M. ; Herrera, J. ; Hose, J. ; Hrupec, D. ; Ishio, K. ; Konno, Y. ; Kubo, H. ; Kushida, J. ; Kuve Dić, D. ; Lelas, D. ; Lindfors, E. ; Lombardi, S. ; Longo, F. ; López, M. ; Maggio, C. ; Majumdar, P. ; Makariev, M. ; Maneva, G. ; Manganaro, M. ; Maraschi, L. ; Mariotti, M. ; Martínez, M. ; Mazin, D. ; Menzel, U. ; Minev, M. ; Miranda, J. M. ; Mirzoyan, R. ; Moralejo, A. ; Moreno, V. ; Moretti, E. ; Nagayoshi, T. ; Neustroev, V. ; Niedzwiecki, A. ; Nievas Rosillo, M. ; Nigro, C. ; Nilsson, K. ; Ninci, D. ; Nishijima, K. ; Noda, K. ; Nogués, L. ; Paiano, S. ; Palacio, J. ; Paneque, D. ; Paoletti, R. ; Paredes, J. M. ; Pedaletti, G. ; Peresano, M. ; Perri, L. ; Persic, M. ; Prada Moroni, P. G. ; Prandini, E. ; Puljak, I. ; Garcia, J. R. ; Reichardt, I. ; Ribó, M. ; Rico, J. ; Righi, C. ; Rugliancich, A. ; Saito, T. ; Satalecka, K. ; Schroeder, S. ; Schweizer, T. ; Shore, S. N. ; Sitarek, J. ; Šnidarić, I. ; Sobczynska, D. ; Stamerra, A. ; Strzys, M. ; Surić, T. ; Takalo, L. ; Tavecchio, F. ; Temnikov, P. ; Terzić, T. ; Teshima, M. ; Torres-Albà, N. ; Treves, A. ; Tsujimoto, S. ; Vanzo, G. ; Vazquez Acosta, M. ; Vovk, I. ; Ward, J. E. ; Will, M. ; Zarić, D. ; Arbet-Engels, A. ; Baack, D. ; Balbo, M. ; Biland, A. ; Blank, M. ; Bretz, T. ; Bruegge, K. ; Bulinski, M. ; Buss, J. ; Dmytriiev, A. ; Dorner, D. ; Einecke, S. ; Elsaesser, D. ; Herbst, T. ; Hildebrand, D. ; Kortmann, L. ; Linhoff, L. ; Mahlke, M. ; Mannheim, K. ; Mueller, S. A. ; Neise, D. ; Neronov, A. ; Noethe, M. ; Oberkirch, J. ; Paravac, A. ; Rhode, W. ; Schleicher, B. ; Schulz, F. ; Sedlaczek, K. ; Shukla, A. ; Sliusar, V. ; Walter, R. ; Archer, A. ; Benbow, W. ; Bird, R. ; Brose, R. ; Buckley, J. H. ; Bugaev, V. ; Christiansen, J. L. ; Cui, W. ; Daniel, M. K. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Gillanders, G. H. ; Gueta, O. ; Hanna, D. ; Hervet, O. ; Holder, J. ; Hughes, G. ; Hütten, M. ; Humensky, T. B. ; Johnson, C. A. ; Kaaret, P. ; Kar, P. ; Kelley-Hoskins, N. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Krennrich, F. ; Kumar, S. ; Lang, M. J. ; Lin, T. T.Y. ; Maier, G. ; McArthur, S. ; Moriarty, P. ; Mukherjee, R. ; O'Brien, S. ; Ong, R. A. ; Otte, A. N. ; Park, N. ; Petrashyk, A. ; Pichel, A. ; Pohl, M. ; Quinn, J. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Rovero, A. C. ; Rulten, C. ; Sadeh, I. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Sushch, I. ; Tyler, J. ; Wakely, S. P. ; Weinstein, A. ; Wells, R. M. ; Wilcox, P. ; Wilhel, A. ; Williams, D. A. ; J Williamson, T. ; Zitzer, B. ; Perri, M. ; Verrecchia, F. ; Leto, C. ; Villata, M. ; Raiteri, C. M. ; Jorstad, S. G. ; Larionov, V. M. ; Blinov, D. A. ; Grishina, T. S. ; Kopatskaya, E. N. ; Larionova, E. G. ; Nikiforova, A. A. ; Morozova, D. A. ; Troitskaya, Yu V. ; Troitsky, I. S. ; Kurtanidze, O. M. ; Nikolashvili, M. G. ; Kurtanidze, S. O. ; Kimeridze, G. N. ; Chigladze, R. A. ; Strigachev, A. ; Sadun, A. C. ; Moody, J. W. ; Chen, W. P. ; Lin, H. C. ; Acosta-Pulido, J. A. ; Arévalo, M. J. ; Carnerero, M. I. ; González-Morales, P. A. ; Manilla-Robles, A. ; Jermak, H. ; Steele, I. ; Mundell, C. ; Benítez, E. ; Hiriart, D. ; Smith, P. S. ; Max-Moerbeck, W. ; Readhead, A. C.S. ; Richards, J. L. ; Hovatta, T. ; Lähteenmäki, A. ; Tornikoski, M. ; Tammi, J. ; Georganopoulos, M. ; Baring, M. G. / Extreme HBL behavior of Markarian 501 during 2012. In: Astronomy and Astrophysics. 2018 ; Vol. 620.
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title = "Extreme HBL behavior of Markarian 501 during 2012",
abstract = "Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign 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. Results. 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. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices < 2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance < 3σ) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. 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 data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone 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 behavior 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.",
author = "Ahnen, {M. L.} and S. Ansoldi and Antonelli, {L. A.} and C. Arcaro and A. Babić and B. Banerjee and P. Bangale and {Barresde Almeida}, U. and Barrio, {J. A.} and J. Becerragonz{\'a}lez 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 Colak, {S. M.} and P. Colin and E. Colombo and Contreras, {J. L.} and J. Cortina and S. Covino and P. Cumani and {Da Vela}, P. and F. Dazzi and {De Angelis}, A. and {De Lotto}, B. and M. Delfino and J. Delgado and {Di Ierro}, F. and M. Doert and A. Dom{\'i}nguez and {Dominis Prester}, D. and M. Doro and {Eisenacher Lawion}, D. and M. Engelkemeier and {Fallah Ramazani}, V. and A. Fern{\'a}ndez-Barral and D. Fidalgo and Fonseca, {M. V.} and L. Font and C. Fruck and D. Galindo and {Garc{\'i}a L{\'o}pez}, {R. J.} 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 {Kuve Dić}, D. and D. Lelas and E. Lindfors and S. Lombardi and F. Longo and M. L{\'o}pez and C. Maggio and P. Majumdar and M. Makariev and G. Maneva and M. Manganaro and L. Maraschi and M. Mariotti and M. Mart{\'i}nez and D. Mazin and U. Menzel and M. Minev and Miranda, {J. M.} and R. Mirzoyan and A. Moralejo and V. Moreno and E. Moretti and T. Nagayoshi and V. Neustroev and A. Niedzwiecki and {Nievas Rosillo}, M. and C. Nigro and K. Nilsson and D. Ninci and K. Nishijima and K. Noda and L. Nogu{\'e}s and S. Paiano and J. Palacio and D. Paneque and R. Paoletti and Paredes, {J. M.} and G. Pedaletti and M. Peresano and L. Perri and M. Persic and {Prada Moroni}, {P. G.} and E. Prandini and I. Puljak and Garcia, {J. R.} and I. Reichardt and M. Rib{\'o} and J. Rico and C. Righi and A. Rugliancich and T. Saito and K. Satalecka and S. Schroeder and T. Schweizer and Shore, {S. N.} 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-Alb{\`a} and A. Treves and S. Tsujimoto and G. Vanzo and {Vazquez Acosta}, M. and I. Vovk and Ward, {J. E.} 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 Mueller, {S. A.} 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 Buckley, {J. H.} and V. Bugaev and Christiansen, {J. L.} and W. Cui and Daniel, {M. K.} and A. Falcone and Q. Feng and Finley, {J. P.} and Gillanders, {G. H.} and O. Gueta and D. Hanna and O. Hervet and J. Holder and G. Hughes and M. H{\"u}tten and Humensky, {T. B.} and Johnson, {C. A.} 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 Lang, {M. J.} and Lin, {T. T.Y.} and G. Maier and S. McArthur and P. Moriarty and R. Mukherjee and S. O'Brien and Ong, {R. A.} and Otte, {A. N.} and N. Park and A. Petrashyk and A. Pichel and M. Pohl and J. Quinn and K. Ragan and Reynolds, {P. T.} and Richards, {G. T.} and E. Roache and Rovero, {A. C.} and C. Rulten and I. Sadeh and M. Santander and Sembroski, {G. H.} and K. Shahinyan and I. Sushch and J. Tyler and Wakely, {S. P.} and A. Weinstein and Wells, {R. M.} and P. Wilcox and A. Wilhel and Williams, {D. A.} and {J Williamson}, T. and B. Zitzer and M. Perri and F. Verrecchia and C. Leto and M. Villata and Raiteri, {C. M.} and Jorstad, {S. G.} and Larionov, {V. M.} and Blinov, {D. A.} and Grishina, {T. S.} and Kopatskaya, {E. N.} and Larionova, {E. G.} and Nikiforova, {A. A.} and Morozova, {D. A.} and Troitskaya, {Yu V.} and Troitsky, {I. S.} and Kurtanidze, {O. M.} and Nikolashvili, {M. G.} and Kurtanidze, {S. O.} and Kimeridze, {G. N.} and Chigladze, {R. A.} and A. Strigachev and Sadun, {A. C.} and Moody, {J. W.} and Chen, {W. P.} and Lin, {H. C.} and Acosta-Pulido, {J. A.} and Ar{\'e}valo, {M. J.} and Carnerero, {M. I.} and Gonz{\'a}lez-Morales, {P. A.} and A. Manilla-Robles and H. Jermak and I. Steele and C. Mundell and E. Ben{\'i}tez and D. Hiriart and Smith, {P. S.} and W. Max-Moerbeck and Readhead, {A. C.S.} and Richards, {J. L.} and T. Hovatta and A. L{\"a}hteenm{\"a}ki and M. Tornikoski and J. Tammi and M. Georganopoulos and Baring, {M. G.}",
year = "2018",
month = "12",
day = "1",
doi = "10.1051/0004-6361/201833704",
language = "English (US)",
volume = "620",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",

}

Ahnen, ML, Ansoldi, S, Antonelli, LA, Arcaro, C, Babić, A, Banerjee, B, Bangale, P, Barresde Almeida, U, Barrio, JA, Becerragonzález, J, Bednarek, W, Bernardini, E, Berti, A, Bhattacharyya, W, Blanch, O, Bonnoli, G, Carosi, R, Carosi, A, Chatterjee, A, Colak, SM, Colin, P, Colombo, E, Contreras, JL, Cortina, J, Covino, S, Cumani, P, Da Vela, P, Dazzi, F, De Angelis, A, De Lotto, B, Delfino, M, Delgado, J, Di Ierro, F, Doert, M, Domínguez, A, Dominis Prester, D, Doro, M, Eisenacher Lawion, D, Engelkemeier, M, Fallah Ramazani, V, Fernández-Barral, A, Fidalgo, D, Fonseca, MV, Font, L, Fruck, C, Galindo, D, García López, RJ, Garczarczyk, M, Gaug, M, Giammaria, P, Godinović, N, Gora, D, Guberman, D, Hadasch, D, Hahn, A, Hassan, T, Hayashida, M, Herrera, J, Hose, J, Hrupec, D, Ishio, K, Konno, Y, Kubo, H, Kushida, J, Kuve Dić, D, Lelas, D, Lindfors, E, Lombardi, S, Longo, F, López, M, Maggio, C, Majumdar, P, Makariev, M, Maneva, G, Manganaro, M, Maraschi, L, Mariotti, M, Martínez, M, Mazin, D, Menzel, U, Minev, M, Miranda, JM, Mirzoyan, R, Moralejo, A, Moreno, V, Moretti, E, Nagayoshi, T, Neustroev, V, Niedzwiecki, A, Nievas Rosillo, M, Nigro, C, Nilsson, K, Ninci, D, Nishijima, K, Noda, K, Nogués, L, Paiano, S, Palacio, J, Paneque, D, Paoletti, R, Paredes, JM, Pedaletti, G, Peresano, M, Perri, L, Persic, M, Prada Moroni, PG, Prandini, E, Puljak, I, Garcia, JR, Reichardt, I, Ribó, M, Rico, J, Righi, C, Rugliancich, A, Saito, T, Satalecka, K, Schroeder, S, Schweizer, T, Shore, SN, Sitarek, J, Šnidarić, I, Sobczynska, D, Stamerra, A, Strzys, M, Surić, T, Takalo, L, Tavecchio, F, Temnikov, P, Terzić, T, Teshima, M, Torres-Albà, N, Treves, A, Tsujimoto, S, Vanzo, G, Vazquez Acosta, M, Vovk, I, Ward, JE, Will, M, Zarić, D, Arbet-Engels, A, Baack, D, Balbo, M, Biland, A, Blank, M, Bretz, T, Bruegge, K, Bulinski, M, Buss, J, Dmytriiev, A, Dorner, D, Einecke, S, Elsaesser, D, Herbst, T, Hildebrand, D, Kortmann, L, Linhoff, L, Mahlke, M, Mannheim, K, Mueller, SA, Neise, D, Neronov, A, Noethe, M, Oberkirch, J, Paravac, A, Rhode, W, Schleicher, B, Schulz, F, Sedlaczek, K, Shukla, A, Sliusar, V, Walter, R, Archer, A, Benbow, W, Bird, R, Brose, R, Buckley, JH, Bugaev, V, Christiansen, JL, Cui, W, Daniel, MK, Falcone, A, Feng, Q, Finley, JP, Gillanders, GH, Gueta, O, Hanna, D, Hervet, O, Holder, J, Hughes, G, Hütten, M, Humensky, TB, Johnson, CA, Kaaret, P, Kar, P, Kelley-Hoskins, N, Kertzman, M, Kieda, D, Krause, M, Krennrich, F, Kumar, S, Lang, MJ, Lin, TTY, Maier, G, McArthur, S, Moriarty, P, Mukherjee, R, O'Brien, S, Ong, RA, Otte, AN, Park, N, Petrashyk, A, Pichel, A, Pohl, M, Quinn, J, Ragan, K, Reynolds, PT, Richards, GT, Roache, E, Rovero, AC, Rulten, C, Sadeh, I, Santander, M, Sembroski, GH, Shahinyan, K, Sushch, I, Tyler, J, Wakely, SP, Weinstein, A, Wells, RM, Wilcox, P, Wilhel, A, Williams, DA, J Williamson, T, Zitzer, B, Perri, M, Verrecchia, F, Leto, C, Villata, M, Raiteri, CM, Jorstad, SG, Larionov, VM, Blinov, DA, Grishina, TS, Kopatskaya, EN, Larionova, EG, Nikiforova, AA, Morozova, DA, Troitskaya, YV, Troitsky, IS, Kurtanidze, OM, Nikolashvili, MG, Kurtanidze, SO, Kimeridze, GN, Chigladze, RA, Strigachev, A, Sadun, AC, Moody, JW, Chen, WP, Lin, HC, Acosta-Pulido, JA, Arévalo, MJ, Carnerero, MI, González-Morales, PA, Manilla-Robles, A, Jermak, H, Steele, I, Mundell, C, Benítez, E, Hiriart, D, Smith, PS, Max-Moerbeck, W, Readhead, ACS, Richards, JL, Hovatta, T, Lähteenmäki, A, Tornikoski, M, Tammi, J, Georganopoulos, M & Baring, MG 2018, 'Extreme HBL behavior of Markarian 501 during 2012', Astronomy and Astrophysics, vol. 620, A181. https://doi.org/10.1051/0004-6361/201833704

Extreme HBL behavior of Markarian 501 during 2012. / Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Arcaro, C.; Babić, A.; Banerjee, B.; Bangale, P.; Barresde Almeida, U.; Barrio, J. A.; Becerragonzález, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Bhattacharyya, W.; Blanch, O.; Bonnoli, G.; Carosi, R.; Carosi, A.; Chatterjee, A.; Colak, S. M.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; Delfino, M.; Delgado, J.; Di Ierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Doro, M.; Eisenacher Lawion, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Ishio, K.; Konno, Y.; Kubo, H.; Kushida, J.; Kuve Dić, D.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Maggio, C.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moreno, V.; Moretti, E.; Nagayoshi, T.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nigro, C.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nogués, L.; Paiano, S.; Palacio, J.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Torres-Albà, N.; Treves, A.; Tsujimoto, S.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Ward, J. E.; Will, M.; Zarić, D.; Arbet-Engels, A.; Baack, D.; Balbo, M.; Biland, A.; Blank, M.; Bretz, T.; Bruegge, K.; Bulinski, M.; Buss, J.; Dmytriiev, A.; Dorner, D.; Einecke, S.; Elsaesser, D.; Herbst, T.; Hildebrand, D.; Kortmann, L.; Linhoff, L.; Mahlke, M.; Mannheim, K.; Mueller, S. A.; Neise, D.; Neronov, A.; Noethe, M.; Oberkirch, J.; Paravac, A.; Rhode, W.; Schleicher, B.; Schulz, F.; Sedlaczek, K.; Shukla, A.; Sliusar, V.; Walter, R.; Archer, A.; Benbow, W.; Bird, R.; Brose, R.; Buckley, J. H.; Bugaev, V.; Christiansen, J. L.; Cui, W.; Daniel, M. K.; Falcone, A.; Feng, Q.; Finley, J. P.; Gillanders, G. H.; Gueta, O.; Hanna, D.; Hervet, O.; Holder, J.; Hughes, G.; Hütten, M.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Kumar, S.; Lang, M. J.; Lin, T. T.Y.; Maier, G.; McArthur, S.; Moriarty, P.; Mukherjee, R.; O'Brien, S.; Ong, R. A.; Otte, A. N.; Park, N.; Petrashyk, A.; Pichel, A.; Pohl, M.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rovero, A. C.; Rulten, C.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Sushch, I.; Tyler, J.; Wakely, S. P.; Weinstein, A.; Wells, R. M.; Wilcox, P.; Wilhel, A.; Williams, D. A.; J Williamson, T.; Zitzer, B.; Perri, M.; Verrecchia, F.; Leto, C.; Villata, M.; Raiteri, C. M.; Jorstad, S. G.; Larionov, V. M.; Blinov, D. A.; Grishina, T. S.; Kopatskaya, E. N.; Larionova, E. G.; Nikiforova, A. A.; Morozova, D. A.; Troitskaya, Yu V.; Troitsky, I. S.; Kurtanidze, O. M.; Nikolashvili, M. G.; Kurtanidze, S. O.; Kimeridze, G. N.; Chigladze, R. A.; Strigachev, A.; Sadun, A. C.; Moody, J. W.; Chen, W. P.; Lin, H. C.; Acosta-Pulido, J. A.; Arévalo, M. J.; Carnerero, M. I.; González-Morales, P. A.; Manilla-Robles, A.; Jermak, H.; Steele, I.; Mundell, C.; Benítez, E.; Hiriart, D.; Smith, P. S.; Max-Moerbeck, W.; Readhead, A. C.S.; Richards, J. L.; Hovatta, T.; Lähteenmäki, A.; Tornikoski, M.; Tammi, J.; Georganopoulos, M.; Baring, M. G.

In: Astronomy and Astrophysics, Vol. 620, A181, 01.12.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Extreme HBL behavior of Markarian 501 during 2012

AU - Ahnen, M. L.

AU - Ansoldi, S.

AU - Antonelli, L. A.

AU - Arcaro, C.

AU - Babić, A.

AU - Banerjee, B.

AU - Bangale, P.

AU - Barresde Almeida, U.

AU - Barrio, J. A.

AU - Becerragonzález, J.

AU - Bednarek, W.

AU - Bernardini, E.

AU - Berti, A.

AU - Bhattacharyya, W.

AU - Blanch, O.

AU - Bonnoli, G.

AU - Carosi, R.

AU - Carosi, A.

AU - Chatterjee, A.

AU - Colak, S. M.

AU - Colin, P.

AU - Colombo, E.

AU - Contreras, J. L.

AU - Cortina, J.

AU - Covino, S.

AU - Cumani, P.

AU - Da Vela, P.

AU - Dazzi, F.

AU - De Angelis, A.

AU - De Lotto, B.

AU - Delfino, M.

AU - Delgado, J.

AU - Di Ierro, F.

AU - Doert, M.

AU - Domínguez, A.

AU - Dominis Prester, D.

AU - Doro, M.

AU - Eisenacher Lawion, D.

AU - Engelkemeier, M.

AU - Fallah Ramazani, V.

AU - Fernández-Barral, A.

AU - Fidalgo, D.

AU - Fonseca, M. V.

AU - Font, L.

AU - Fruck, C.

AU - Galindo, D.

AU - García López, R. J.

AU - Garczarczyk, M.

AU - Gaug, M.

AU - Giammaria, P.

AU - Godinović, N.

AU - Gora, D.

AU - Guberman, D.

AU - Hadasch, D.

AU - Hahn, A.

AU - Hassan, T.

AU - Hayashida, M.

AU - Herrera, J.

AU - Hose, J.

AU - Hrupec, D.

AU - Ishio, K.

AU - Konno, Y.

AU - Kubo, H.

AU - Kushida, J.

AU - Kuve Dić, D.

AU - Lelas, D.

AU - Lindfors, E.

AU - Lombardi, S.

AU - Longo, F.

AU - López, M.

AU - Maggio, C.

AU - Majumdar, P.

AU - Makariev, M.

AU - Maneva, G.

AU - Manganaro, M.

AU - Maraschi, L.

AU - Mariotti, M.

AU - Martínez, M.

AU - Mazin, D.

AU - Menzel, U.

AU - Minev, M.

AU - Miranda, J. M.

AU - Mirzoyan, R.

AU - Moralejo, A.

AU - Moreno, V.

AU - Moretti, E.

AU - Nagayoshi, T.

AU - Neustroev, V.

AU - Niedzwiecki, A.

AU - Nievas Rosillo, M.

AU - Nigro, C.

AU - Nilsson, K.

AU - Ninci, D.

AU - Nishijima, K.

AU - Noda, K.

AU - Nogués, L.

AU - Paiano, S.

AU - Palacio, J.

AU - Paneque, D.

AU - Paoletti, R.

AU - Paredes, J. M.

AU - Pedaletti, G.

AU - Peresano, M.

AU - Perri, L.

AU - Persic, M.

AU - Prada Moroni, P. G.

AU - Prandini, E.

AU - Puljak, I.

AU - Garcia, J. R.

AU - Reichardt, I.

AU - Ribó, M.

AU - Rico, J.

AU - Righi, C.

AU - Rugliancich, A.

AU - Saito, T.

AU - Satalecka, K.

AU - Schroeder, S.

AU - Schweizer, T.

AU - Shore, S. N.

AU - Sitarek, J.

AU - Šnidarić, I.

AU - Sobczynska, D.

AU - Stamerra, A.

AU - Strzys, M.

AU - Surić, T.

AU - Takalo, L.

AU - Tavecchio, F.

AU - Temnikov, P.

AU - Terzić, T.

AU - Teshima, M.

AU - Torres-Albà, N.

AU - Treves, A.

AU - Tsujimoto, S.

AU - Vanzo, G.

AU - Vazquez Acosta, M.

AU - Vovk, I.

AU - Ward, J. E.

AU - Will, M.

AU - Zarić, D.

AU - Arbet-Engels, A.

AU - Baack, D.

AU - Balbo, M.

AU - Biland, A.

AU - Blank, M.

AU - Bretz, T.

AU - Bruegge, K.

AU - Bulinski, M.

AU - Buss, J.

AU - Dmytriiev, A.

AU - Dorner, D.

AU - Einecke, S.

AU - Elsaesser, D.

AU - Herbst, T.

AU - Hildebrand, D.

AU - Kortmann, L.

AU - Linhoff, L.

AU - Mahlke, M.

AU - Mannheim, K.

AU - Mueller, S. A.

AU - Neise, D.

AU - Neronov, A.

AU - Noethe, M.

AU - Oberkirch, J.

AU - Paravac, A.

AU - Rhode, W.

AU - Schleicher, B.

AU - Schulz, F.

AU - Sedlaczek, K.

AU - Shukla, A.

AU - Sliusar, V.

AU - Walter, R.

AU - Archer, A.

AU - Benbow, W.

AU - Bird, R.

AU - Brose, R.

AU - Buckley, J. H.

AU - Bugaev, V.

AU - Christiansen, J. L.

AU - Cui, W.

AU - Daniel, M. K.

AU - Falcone, A.

AU - Feng, Q.

AU - Finley, J. P.

AU - Gillanders, G. H.

AU - Gueta, O.

AU - Hanna, D.

AU - Hervet, O.

AU - Holder, J.

AU - Hughes, G.

AU - Hütten, M.

AU - Humensky, T. B.

AU - Johnson, C. A.

AU - Kaaret, P.

AU - Kar, P.

AU - Kelley-Hoskins, N.

AU - Kertzman, M.

AU - Kieda, D.

AU - Krause, M.

AU - Krennrich, F.

AU - Kumar, S.

AU - Lang, M. J.

AU - Lin, T. T.Y.

AU - Maier, G.

AU - McArthur, S.

AU - Moriarty, P.

AU - Mukherjee, R.

AU - O'Brien, S.

AU - Ong, R. A.

AU - Otte, A. N.

AU - Park, N.

AU - Petrashyk, A.

AU - Pichel, A.

AU - Pohl, M.

AU - Quinn, J.

AU - Ragan, K.

AU - Reynolds, P. T.

AU - Richards, G. T.

AU - Roache, E.

AU - Rovero, A. C.

AU - Rulten, C.

AU - Sadeh, I.

AU - Santander, M.

AU - Sembroski, G. H.

AU - Shahinyan, K.

AU - Sushch, I.

AU - Tyler, J.

AU - Wakely, S. P.

AU - Weinstein, A.

AU - Wells, R. M.

AU - Wilcox, P.

AU - Wilhel, A.

AU - Williams, D. A.

AU - J Williamson, T.

AU - Zitzer, B.

AU - Perri, M.

AU - Verrecchia, F.

AU - Leto, C.

AU - Villata, M.

AU - Raiteri, C. M.

AU - Jorstad, S. G.

AU - Larionov, V. M.

AU - Blinov, D. A.

AU - Grishina, T. S.

AU - Kopatskaya, E. N.

AU - Larionova, E. G.

AU - Nikiforova, A. A.

AU - Morozova, D. A.

AU - Troitskaya, Yu V.

AU - Troitsky, I. S.

AU - Kurtanidze, O. M.

AU - Nikolashvili, M. G.

AU - Kurtanidze, S. O.

AU - Kimeridze, G. N.

AU - Chigladze, R. A.

AU - Strigachev, A.

AU - Sadun, A. C.

AU - Moody, J. W.

AU - Chen, W. P.

AU - Lin, H. C.

AU - Acosta-Pulido, J. A.

AU - Arévalo, M. J.

AU - Carnerero, M. I.

AU - González-Morales, P. A.

AU - Manilla-Robles, A.

AU - Jermak, H.

AU - Steele, I.

AU - Mundell, C.

AU - Benítez, E.

AU - Hiriart, D.

AU - Smith, P. S.

AU - Max-Moerbeck, W.

AU - Readhead, A. C.S.

AU - Richards, J. L.

AU - Hovatta, T.

AU - Lähteenmäki, A.

AU - Tornikoski, M.

AU - Tammi, J.

AU - Georganopoulos, M.

AU - Baring, M. G.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign 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. Results. 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. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices < 2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance < 3σ) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. 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 data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone 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 behavior 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.

AB - Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign 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. Results. 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. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices < 2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance < 3σ) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. 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 data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone 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 behavior 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.

UR - http://www.scopus.com/inward/record.url?scp=85058842268&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85058842268&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201833704

DO - 10.1051/0004-6361/201833704

M3 - Article

AN - SCOPUS:85058842268

VL - 620

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A181

ER -

Ahnen ML, Ansoldi S, Antonelli LA, Arcaro C, Babić A, Banerjee B et al. Extreme HBL behavior of Markarian 501 during 2012. Astronomy and Astrophysics. 2018 Dec 1;620. A181. https://doi.org/10.1051/0004-6361/201833704