TeV and Multi-wavelength Observations of Mrk 421 in 2006-2008

Acciari, V. A.; Aliu, E.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Boltuch, D.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cannon, A.; Cesarini, A.; Ciupik, L.; Cui, W.; Dickherber, R.; Duke, C.; Falcone, A.; Finley, J. P.; Finnegan, G.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Gillanders, G. H.; Godambe, S.; Grube, J.; Guenette, R.; Gyuk, G.; Hanna, D.; Holder, J.; Hui, C. M.; Humensky, T. B.; Imran, A.; Kaaret, P.; Karlsson, N.; Kertzman, M.; Kieda, D.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Maier, G.; McArthur, S.; McCutcheon, M.; Moriarty, P.; Ong, R. A.; Otte, A. N.; Ouellette, M.; Pandel, D.; Perkins, J. S.; Pichel, A.; Pohl, M.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Roache, E.; Rose, H. J.; Rovero, A. C.; Schroedter, M.; Sembroski, G. H.; Senturk, G. Demet; Steele, D.; Swordy, S. P.; Theiling, M.; Thibadeau, S.; Varlotta, A.; Vassiliev, V. V.; Vincent, S.; Wagner, R. G.; Wakely, S. P.; Ward, J. E.; Weekes, T. C.; Weinstein, A.; Weisgarber, T.; Williams, D. A.; Wissel, S.; Wood, M.; Zitzer, B.; Garson, A.; Lee, K.; Sadun, A. C.; Carini, M.; Barnaby, D.; Cook, K.; Maune, J.; Pease, A.; Smith, S.; Walters, R.; Berdyugin, A.; Lindfors, E.; Nilsson, K.; Pasanen, M.; Sainio, J.; Sillanpaa, A.; Takalo, L. O.; Villforth, C.; Montaruli, T.; Baker, M.; Lahteenmaki, A.; Tornikoski, M.; Hovatta, T.; Nieppola, E.; Aller, H. D.; Aller, M. F.

doi:10.48550/arxiv.1106.1210

Cited by 4 publications

(4 citation statements)

References 49 publications

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“…Therefore, these sources require long-term observations to be detected in a low-flux state. Although detections in high-flux states (flares) for these sources already exist, it cannot be assumed that IBLs will exhibit the same spectral behavior in a low-flux state; there is already ample evidence of spectral variability for HBLs between high-and low-flux states [7,8]. In particular, it is important to ascertain whether the "quiescent" or low-flux-state SED for IBLs requires an external photon field to appropriately model the IC peak.…”

Section: Introductionmentioning

confidence: 99%

VHE Analyses of Long-Term Low-Flux-State Observations by VERITAS of Intermediate-Frequency-Peaked BL Lacertae Sources: 3C 66A and W Comae

Vievering

2015

Preprint

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Intermediate-frequency-peaked BL Lacertae objects (IBLs) are a class of blazars characterized by a spectral energy distribution (SED) with a lower-energy synchrotron peak than the majority of extragalactic sources detected by ground-based imaging atmospheric Cherenkov telescopes (IACTs). Consequently, the peak gamma-ray flux falls outside the very-high-energy regime (VHE, >100 GeV) covered by IACTs such as VERITAS, making IBLs difficult to detect except during infrequent episodes of elevated flux. However, the study of these sources in a low-flux state is essential for developing a complete understanding of the blazar paradigm. We present the results of VHE analyses of long-term low-flux-state observations completed for two IBL sources: 3C 66A and W Comae. For both sources, data from VERITAS were analyzed for the VHE regime. The study of 3C 66A extends from 2007 to 2015, resulting in a 12 standard deviation (σ ) detection from ∼61 observing hours. Analysis of W Comae from 2010 to 2014, totaling ∼39 hours, resulted in a 6σ low-flux-state detection. We report on the results from these VHE analyses and describe contemporaneous multiwavelength data to be used in further analyses. We comment on how these low-flux-state IBL detections fit within the context of the blazar paradigm.

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Section: Introductionmentioning

confidence: 99%

VHE Analyses of Long-Term Low-Flux-State Observations by VERITAS of Intermediate-Frequency-Peaked BL Lacertae Sources: 3C 66A and W Comae

Vievering

2015

Preprint

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“…However, during the TeV high state in November 2009 [5], VER J0521+211 showed more HBL-like properties, especially given the observed spectral hardening in the X-ray regime with increased flux. The observed variability and its bright TeV flux motivated further multiwavelength observations of VER J0521+211 in order to extend the detailed time-resolved spectral modeling available for nearby HBLs [6,7,8] to a more luminous blazar which are reported here.…”

Section: Introductionmentioning

confidence: 73%

Time-resolved multiwavelength observations of the blazar VER J0521+211 from radio to gamma-ray energies

Prokoph¹,

Vela²,

Schultz³

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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VER J0521+211 (RGB J0521.8+2112) is one of the brightest and most powerful blazars detected in the TeV gamma-ray regime. It is located at a redshift of z = 0.108 and since its discovery in 2009, VER J0521+211 has exhibited an average TeV flux exceeding 0.1 times that of the Crab Nebula, corresponding to an isotropic luminosity of 3 × 10 44 erg s −1 . We present data from a comprehensive multiwavelength campaign on this object extending between November 2012 and February 2014, including single-dish radio observations, optical photometry and polarimetry, UV, X-ray, GeV and TeV gamma-ray data (VERITAS, MAGIC). Significant flux variability was observed at all wavelengths, including a long-lasting high state at gamma-ray energies in Fall 2013. Nightly-resolved spectra at X-ray and TeV energies are be presented, and emission mechanisms explaining the observed flux and spectral variability are discussed.

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“…In section 3.5 we found the intuitive result that the uncertainty in any measured dispersion scales inversely with the hardness of the energy spectrum. This also leads to the slightly counterintuitive consequence that a nearer AGN such as Mrk 421 in a high state (eg [20,21]) could provide as constraining a limit, if not more so, than a more distant object (like PKS 2155-304) if it showed similar variability timescales. This is solely due to the harder observed spectra, meaning an increased number of high energy photons being detectable from the nearer object (due to less absorption by the extragalactic background light).…”

Section: Discussionmentioning

confidence: 99%

A Simple Method to Test for Energy-Dependent Dispersion in High Energy Light-Curves of Astrophysical Sources

de Almeida,

Daniel

2012

Preprint

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In this paper we discuss a simple method of testing for the presence of energy-dependent dispersion in high energy data-sets. It uses the minimisation of the Kolmogorov distance between the cumulative distribution of two probability functions as the statistical metric to estimate the magnitude of any spectral dispersion within transient features in a light-curve and we also show that it performs well in the presence of modest energy resolutions (∼ 20%) typical of gamma-ray observations. After presenting the method in detail we apply it to a parameterised simulated lightcurve based on the extreme VHE gamma-ray flare of PKS 2155-304 observed with H.E.S.S. in 2006, in order to illustrate its potential through the concrete example of setting constraints on quantum-gravity induced Lorentz invariance violation (LIV) effects. We obtain comparable limits to those of the most advanced techniques used in LIV searches applied to similar datasets, but the present method has the advantage of being particularly straightforward to use. Whilst the development of the method was motivated by LIV searches, it is also applicable to other astrophysical situations where energy-dependent dispersion is expected, such as spectral lags from the acceleration and cooling of particles in relativistic outflows.

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TeV and Multi-wavelength Observations of Mrk 421 in 2006-2008

Cited by 4 publications

References 49 publications

VHE Analyses of Long-Term Low-Flux-State Observations by VERITAS of Intermediate-Frequency-Peaked BL Lacertae Sources: 3C 66A and W Comae

VHE Analyses of Long-Term Low-Flux-State Observations by VERITAS of Intermediate-Frequency-Peaked BL Lacertae Sources: 3C 66A and W Comae

Time-resolved multiwavelength observations of the blazar VER J0521+211 from radio to gamma-ray energies

A Simple Method to Test for Energy-Dependent Dispersion in High Energy Light-Curves of Astrophysical Sources

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