Observations of the flux of very-high-energy gamma rays from the blazar 3C 66A

Stepanyan, A. A.; Neshpor, Yu. I.; Andreeva, N. A.; Kalekin, O.; Zhogolev, N. A.; Fomin, V. P.; Shitov, V. G.

doi:10.1134/1.1502223

Cited by 20 publications

(18 citation statements)

References 6 publications

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“…This distortion adds to that caused by the absorption of the gamma-ray photons with UV and IR photons of the Extragalactic Background Light (see Fig.2.1). The photon flux recently measured by some experiments, in particular at TeV energies, already exceeds that predicted by conventional models which attempt to explain spectra in terms of observed source spectra and/ or EBL density [144,145,146,147,148], one should not expect a photon flux as high as recently measured by some experiments, in particular at TeV energies. The hard spectrum deduced for some AGN is difficult to explain with conventional physics as well.…”

Section: Axion-like Particle Searchesmentioning

confidence: 62%

Dark matter and fundamental physics with the Cherenkov Telescope Array

Doro

Conrad

Emmanoulopoulos

et al. 2013

Astroparticle Physics

143

198

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The Cherenkov Telescope Array (CTA) is a project for a next-generation observatory for very high energy (GeV–TeV) ground-based gamma-ray astronomy, currently in its design phase, and foreseen to be operative a few years from now. Several tens of telescopes of 2–3 different sizes, distributed over a large area, will allow for a sensitivity about a factor 10 better than current instruments such as H.E.S.S, MAGIC and VERITAS, an energy coverage from a few tens of GeV to several tens of TeV, and a field of view of up to 10°. In the following study, we investigate the prospects for CTA to study several science questions that can profoundly influence our current knowledge of fundamental physics. Based on conservative assumptions for the performance of the different CTA telescope configurations currently under discussion, we employ a Monte Carlo based approach to evaluate the prospects for detection and characterisation of new physics with the array. First, we discuss CTA prospects for cold dark matter searches, following different observational strategies: in dwarf satellite galaxies of the Milky Way, which are virtually void of astrophysical background and have a relatively well known dark matter density; in the region close to the Galactic Centre, where the dark matter density is expected to be large while the astrophysical background due to the Galactic Centre can be excluded; and in clusters of galaxies, where the intrinsic flux may be boosted significantly by the large number of halo substructures. The possible search for spatial signatures, facilitated by the larger field of view of CTA, is also discussed. Next we consider searches for axion-like particles which, besides being possible candidates for dark matter may also explain the unexpectedly low absorption by extragalactic background light of gamma-rays from very distant blazars. We establish the axion mass range CTA could probe through observation of long-lasting flares in distant sources. Simulated light-curves of flaring sources are also used to determine the sensitivity to violations of Lorentz invariance by detection of the possible delay between the arrival times of photons at different energies. Finally, we mention searches for other exotic physics with CTA

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Section: Axion-like Particle Searchesmentioning

confidence: 62%

Dark matter and fundamental physics with the Cherenkov Telescope Array

Doro

Conrad

Emmanoulopoulos

et al. 2013

Astroparticle Physics

143

198

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“…Recently, the MAGIC collaboration (Aliu et al 2009) reported the detection, during observations taking place between 2007 August and December, of a new source, MAGIC J0223+430, located close to the position of the BL Lac object 3C 66A. This blazar (with probable redshift z = 0.444, Miller, French & Hawley 1978, but see Finke et al 2008) has been considered as a TeV candidate since a long time (Neshpor et al 1998; Stepanyan et al 2002) and it has been recently detected by the Very Energetic Radiation Imaging Telescope Array System (VERITAS; with a soft spectrum, Swordy 2008). However, a careful analysis of the MAGIC data shows that the events with energies above ∼150 GeV are rather centred on the position of the near (6 arcmin) FR I radio galaxy 3C 66B (located at 85.5 Mpc), with a probability of 95.4 per cent (decreasing to 85.4 per cent if systematic uncertainties on the positioning are taken into account) that MAGIC J0223+430 is not related to 3C 66A.…”

Section: Introductionmentioning

confidence: 99%

3C 66B as a TeV radio galaxy

Tavecchio¹,

Ghisellini²

2009

Monthly Notices of the Royal Astronomical Society: Letters

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The Major Atmospheric Gamma‐ray Imaging Cherenkov (MAGIC) Telescope collaboration reported the detection of a new very high energy source, MAGIC J0223+430, located close to the position of the blazar 3C 66A, considered a candidate TeV blazar since a long time. A careful analysis showed that the events with energies above 150 GeV are centred on the position of the Fanaro–Riley type I radio galaxy 3C 66B (at 6 arcmin from 3C 66A), with a probability of 95.4 per cent (85.4 per cent including systematic uncertainties) that the source is not related to 3C 66A. We present a model for the possible emission of 3C 66B based on the structured jet model already used to interpret the TeV emission of the radio galaxy M87. The model requires parameters similar to those used for M87 but a larger luminosity for the layer, to account for the more luminous TeV emission. We also show that the spectrum obtained by MAGIC can be interpreted as the combined emission of 3C 66B, dominating above ∼200 GeV, and 3C 66A. The high‐energy emission from the latter source, being strongly attenuated by the interaction with the extragalactic background light, can only contribute at low energies. If we were to see the jet emission of 3C 66B at small viewing angles, we would see a spectral energy distribution closely resembling the one of S5 0716+714, a typical blazar.

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“…Repeated detections above 900 GeV by the Crimean Astrophysical Observatory's GT-48 imaging atmospheric Cerenkov telescope (Neshpor et al 1998;Stepanyan et al 2002) at an average integral flux level of 2:4 ; 10 À11 cm À2 s…”

Section: Introductionmentioning

confidence: 99%

Observations of the BL Lacertae Object 3C 66A with STACEE

Bramel

Carson

Covault

et al. 2005

ApJ

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We present the analysis and results of recent high-energy gamma-ray observations of the BL Lac object 3C 66A conducted with the Solar Tower Atmospheric Cerenkov Effect Experiment (STACEE). During the 2003-2004 observing season, STACEE extensively observed 3C 66A as part of a multiwavelength campaign on the source. A total of 33.7 hr of data was taken on the source, plus an equivalent-duration background observation. After cleaning the data set a total of 16.3 hr of live time remained, and a net on-source excess of 1134 events was seen against a background of 231,742 events. At a significance of 2.2 this excess is insufficient to claim a detection of 3C 66A but is used to establish flux upper limits for the source.

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Observations of the flux of very-high-energy gamma rays from the blazar 3C 66A

Cited by 20 publications

References 6 publications

Dark matter and fundamental physics with the Cherenkov Telescope Array

Dark matter and fundamental physics with the Cherenkov Telescope Array

3C 66B as a TeV radio galaxy

Observations of the BL Lacertae Object 3C 66A with STACEE

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