LONG-TERM MONITORING OF MRK 501 FOR ITS VERY HIGH ENERGY Γ EMISSION AND a FLARE IN 2011 OCTOBER

Bartoli, B.; Bernardini, P.; Bi, X. J.; Bleve, C.; Bolognino, I.; Branchini, P.; Budano, A.; Melcarne, A. K. Calabrese; Camarri, P.; Cao, Z.; Cardarelli, R.; Catalanotti, S.; Cattaneo, Claudio; Chen, Songzhan; Chen, T. L.; Chen, Y.; Creti, P.; Cui, S. W.; Dai, B. Z.; Staiti, G. DʼAlí; Danzengluobu,; Dattoli, M.; Mitri, I. De; Piazzoli, B. D’Ettorre; Girolamo, T. Di; Ding, X. H.; Sciascio, G. Di; Feng, C.; Feng, Z.; Feng, Z. Y.; Galeazzi, F.; Giroletti, E.; Gou, Q. B.; Guo, Y. Q.; He, H. H.; Hu, Haibing; Hu, Hongbo; Huang, Q.; Iacovacci, M.; Iuppa, R.; James, I.; Jia, H. Y.; Labaciren,; Li, H. J.; Li, J. Y.; Li, X. X.; Liguori, G.; Liu, C.; Liu, C. Q.; Liu, J.; Liu, M. Y.; Lü, H.; L., L.; H., X.; Mancarella, G.; Mari, Stefano Maria; Marsella, G.; Martello, D.; Mastroianni, S.; Montini, P.; Ning, C. C.; Pagliaro, A.; Panareo, M.; Panico, B.; Perrone, L.; Pistilli, P.; Ruggieri, F.; Salvini, P.; Santonico, R.; Shen, P. R.; Sheng, X. D.; Shi, Feng; Stănescu, C.; Surdo, A.; Tan, Y. H.; Vallania, P.; Vernetto, S.; Vigorito, C.; Wang, Bo; Wang, H.; Wu, C. Y.; Wu, H. R.; Xu, Benda; Xue, L.; Yang, Q. Y.; Yang, X. C.; Yao, Z. G.; Yuan, A. F.; Zha, M.; Zhang, H. M.; Zhang, Jilong; Zhang, Jianli; Zhang, L.; Zhang, P.; Zhang, X. Y.; Zhang, Y.; Zhao, J.; Zhaxiciren,; Zhaxisangzhu,; Zhou, X. X.; Zhu, F. R.; Zhu, Q. Q.; Zizzi, and G.

doi:10.1088/0004-637x/758/1/2

Cited by 58 publications

(43 citation statements)

References 38 publications

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“…China. It is mainly devoted to γ-ray astronomy (Bartoli et al 2012a(Bartoli et al , 2012b(Bartoli et al , 2012c(Bartoli et al , 2013b(Bartoli et al , 2014(Bartoli et al , 2015 and cosmic ray physics (Bartoli et al 2012d(Bartoli et al , 2012e, 2013c. The detector consists of a carpet (∼74 × 78 m 2 ) of resistive plate chambers (RPCs) with ∼93% of active area, surrounded by a partially instrumented area (∼20%) up to ∼100×110 m 2 .…”

Section: Argo-ybj Vhe γ-Ray Datamentioning

confidence: 99%

4.5 Years of Multi-Wavelength Observations of MRK 421 During the Argo-Ybj and Fermi Common Operation Time

Bartoli

Bernardini

et al. 2016

ApJS

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We report on the extensive multi-wavelength observations of the blazar Markarian 421 (Mrk 421) covering radio to γ-rays, during the 4.5 year period of ARGO-YBJ and Fermi common operation time, from 2008 August to 2013 February. These long-term observations, extending over an energy range of 18 orders of magnitude, provide a unique chance to study the variable emission of Mrk 421. In particular, due to the ARGO-YBJ and Fermi data, the entireenergy range from 100 MeV to 10 TeV is covered without any gap. In the observation period, Mrk 421 showed both low-and high-activity states at all wavebands. The correlations among flux variations in different wavebands were analyzed. The X-ray flux is clearly correlated with the TeV γ-ray flux, while the GeV γ-rays only show a partial correlation with the TeV γ-rays. Radio and UV fluxes seem to be weakly or not correlated with the X-ray and γ-ray fluxes. Seven large flares, including five X-ray flares and two GeV γ-ray flares with variable durations (3-58 days), and one X-ray outburst phase were identified and used to investigate the variation of the spectral energy distribution with respect to a relative quiescent phase. During the outburst phase and the seven flaring episodes, the peak energy in X-rays is observed to increase from sub-keV to a few keV. The TeV γ-ray flux increases up to 0.9-7.2 times the flux of the Crab Nebula. The behavior of GeV γ-rays is found to vary depending on the flare, a feature that leads us to classify flares into three groups according to the GeV flux variation. Finally, the one-zone synchrotron self-Compton model was adopted to describe the emission spectra. Two out of three groups can be satisfactorily described using injected electrons with a power-law spectral index around 2.2, as expected from relativistic diffuse shock acceleration, whereas the remaining group requires a harder injected spectrum. The underlying physical mechanisms responsible for different groups may be related to the acceleration process or to the environment properties.

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Section: Argo-ybj Vhe γ-Ray Datamentioning

confidence: 99%

4.5 Years of Multi-Wavelength Observations of MRK 421 During the Argo-Ybj and Fermi Common Operation Time

Bartoli

Bernardini

et al. 2016

ApJS

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“…An exception is the large campaign on the low state of 1ES 2344+514 (Aleksić et al 2013). Other campaigns involving a large number of instruments are only available for few bright sources, such as 3C 454.3 Abdo et al 2009;Vercellone et al 2009;Pacciani et al 2010), Mrk 421 (Błażejowski et al 2005;Donnarumma et al 2009;Abdo et al 2011b; Bartoli et al 2016;Baloković et al 2016), Mrk 501 (Bartoli et al 2012;Aleksić et al 2015;Furniss et al 2015), 3C279 (Grandi et al 1996;Wehrle et al 1998;Hayashida et al 2015;Paliya et al 2015), BL Lac (Abdo et al 2011a;Wehrle et al 2016), S5 0716+714 (Rani et al 2013;Liao et al 2014;Chandra et al 2015), and PKS 2155−304 (Aharonian et al 2009;Abdo et al 2010a).…”

Section: Introductionmentioning

confidence: 99%

The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars

Krauß

Wilms

Kadler

et al. 2016

A&A

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Context. Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics. Aims. We study the spectral evolution between quiescent and flaring periods of 22 radio-loud AGN through multiepoch, quasisimultaneous broadband spectra. For many of these sources these are the first broadband studies. Methods. We use a Bayesian block analysis of Fermi/LAT light curves to determine time ranges of constant flux for constructing quasi-simultaneous spectral energy distributions (SEDs). The shapes of the resulting 81 SEDs are described by two logarithmic parabolas and a blackbody spectrum where needed. Results. The peak frequencies and luminosities agree well with the blazar sequence for low states with higher luminosity implying lower peak frequencies. This is not true for sources in high states. The γ-ray photon index in Fermi/LAT correlates with the synchrotron peak frequency in low and intermediate states. No correlation is present in high states. The black hole mass cannot be determined from the SEDs. Surprisingly, the thermal excess often found in FSRQs at optical/UV wavelengths can be described by blackbody emission and not an accretion disk spectrum. Conclusions. The so-called harder-when-brighter trend, typically seen in X-ray spectra of flaring blazars, is visible in the blazar sequence. Our results for low and intermediate states, as well as the Compton dominance, are in agreement with previous results. Black hole mass estimates using recently published parameters are in agreement with some of the more direct measurements. For two sources, estimates disagree by more than four orders of magnitude, possibly owing to boosting effects. The shapes of the thermal excess seen predominantly in flat spectrum radio quasars are inconsistent with a direct accretion disk origin.

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“…The ARGO-YBJ detector is an EAS array with a large field of view (FOV) and can observe gamma rays at an energy threshold of ∼300 GeV. Previously, the ARGO-YBJ collaboration achieved some important results in TeV gamma-ray observations, e. g. flaring activity of AGNs (Bartoli et al 2012(Bartoli et al , 2016, northern sky survey (Bartoli et al 2013), Cygnus Cocoon (Bartoli et al 2014), Galactic plane diffuse gamma-ray emission (Bartoli et al 2015). The ARGO-YBJ sensitivity for a gamma point source is about 24% Crab flux, however the large mismatch between the observed flux at low energies and the theoretical predictions, and the chance to probe new physics, motivate an observational search for sub-TeV/TeV gamma rays from the Sun direction .…”

mentioning

confidence: 99%

Search for Gamma-Ray Emission from the Sun during Solar Minimum with the ARGO-YBJ Experiment

Bartoli¹,

Bernardini²,

Bi³

et al. 2019

ApJ

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The hadronic interaction of cosmic rays with solar atmosphere can produce high energy gamma rays. The gamma-ray luminosity is correlated both with the flux of primary cosmic rays and the intensity of the solar magnetic field. The gamma rays below 200 GeV have been observed by Fermi without any evident energy cutoff. The bright gamma-ray flux above 100 GeV has been detected only during solar minimum. The only available data in TeV range come from the HAWC observations, however outside the solar minimum. The ARGO-YBJ dataset has been used to search for sub-TeV/TeV gamma rays from the Sun during the solar minimum from 2008 to 2010, the same time period covered by the Fermi data. A suitable model containing the Sun shadow, solar disk emission and inverse-Compton emission has been developed, and the chi-square minimization method was used to quantitatively estimate the disk gamma-ray signal. The result shows that no significant gamma-ray signal is detected and upper limits to the gamma-ray flux at 0.3−7 TeV are set at 95% confidence level. In the low energy range these limits are consistent with the extrapolation of the Fermi-LAT measurements taken during solar minimum and are compatible with a softening of the gamma-ray spectrum below 1 TeV. They provide also an experimental upper bound to any solar disk emission at TeV energies. Models of dark matter annihilation via long-lived mediators predicting gamma-ray fluxes > 10 −7 GeV cm −2 s −1 below 1 TeV are ruled out by the ARGO-YBJ limits.

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LONG-TERM MONITORING OF MRK 501 FOR ITS VERY HIGH ENERGY Γ EMISSION AND a FLARE IN 2011 OCTOBER

Cited by 58 publications

References 38 publications

4.5 Years of Multi-Wavelength Observations of MRK 421 During the Argo-Ybj and Fermi Common Operation Time

4.5 Years of Multi-Wavelength Observations of MRK 421 During the Argo-Ybj and Fermi Common Operation Time

The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars

Search for Gamma-Ray Emission from the Sun during Solar Minimum with the ARGO-YBJ Experiment

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