TY - JOUR

T1 - Extreme HBL behavior of Markarian 501 during 2012

AU - MAGIC Collaboration

AU - FACT Collaboration

AU - VERITAS Collaboration

AU - Ahnen, M. L.

AU - Ansoldi, S.

AU - Antonelli, L. A.

AU - Arcaro, C.

AU - Babic, A.

AU - Banerjee, B.

AU - Bangale, P.

AU - Barres de Almeida, U.

AU - Barrio, J. A.

AU - Gonzalez, J. Becerra

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 Pierro, F.

AU - Doert, M.

AU - Dominguez, A.

AU - Prester, D. Dominis

AU - Doro, M.

AU - Glawion, D. Eisenacher

AU - Engelkemeier, M.

AU - Ramazani, V. Fallah

AU - Fernandez-Barral, A.

AU - Fidalgo, D.

AU - Fonseca, M. V.

AU - Font, L.

AU - Larionov, V. M.

AU - Blinov, D. A.

AU - Grishina, T. S.

AU - Larionova, E. G.

AU - Nikiforova, A. A.

AU - Morozova, D. A.

AU - Копацкая, Евгения Николаевна

AU - Троицкая, Юлия Вячеславовна

AU - Троицкий, Иван Станиславович

PY - 2018/12/14

Y1 - 2018/12/14

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 similar to 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 similar to 3 CU, and the peak of the high-energy spectral component was found to be at similar to 2 TeV. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indicesConclusions. 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 similar to 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 similar to 3 CU, and the peak of the high-energy spectral component was found to be at similar to 2 TeV. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indicesConclusions. 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.

KW - astroparticle physics

KW - acceleration of particles

KW - radiation mechanisms: non-thermal

KW - BL Lacertae objects: general

KW - BL Lacertae objects: individual: Mrk501

KW - EXTRAGALACTIC BACKGROUND LIGHT

KW - ACTIVE GALACTIC NUCLEI

KW - GAMMA-RAY EMISSION

KW - BL-LAC OBJECTS

KW - X-RAY

KW - MULTIWAVELENGTH OBSERVATIONS

KW - TEV BLAZARS

KW - 3C 454.3

KW - ENERGY

KW - VARIABILITY

U2 - 10.1051/0004-6361/201833704

DO - 10.1051/0004-6361/201833704

M3 - статья

VL - 620

JO - ASTRONOMY & ASTROPHYSICS

JF - ASTRONOMY & ASTROPHYSICS

SN - 0004-6361

M1 - 181

ER -