Teraelectronvolt Astronomy

Hinton, J. A.; Hofmann, W.

doi:10.1146/annurev-astro-082708-101816

Cited by 318 publications

(300 citation statements)

References 145 publications

(128 reference statements)

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“…De Angelis et al 2008;Hinton & Hofmann 2009). The majority of them are BL Lac objects, in particular those with the synchrotron bump peaking in the UV/X-ray band (highly peaked BL Lac, HBLs, Padovani & Giommi 1995).…”

Section: Introductionmentioning

confidence: 99%

On the origin of theγ-ray emission from the flaring blazar PKS 1222+216

Tavecchio

González

Ghisellini

et al. 2011

A&A

164

196

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The flat spectrum radio quasar PKS 1222+216 (4C+21.35, z = 0.432) was detected in the very high energy γ-ray band by MAGIC during a highly active γ-ray phase following an alert by the Large Area Telescope (LAT) onboard Fermi. Its relatively hard spectrum (70-400 GeV photon index Γ = 2.7 ± 0.3) without a cut off, together with the observed variability on timescale of ∼ 10 min challenges standard emission models. In particular, if the emission originates in a portion of the relativistic jet located inside the broad line region (BLR), severe absorption of γ rays above few tens of GeV is expected due to the γγ → e ± process. These observations therefore imply the existence of a very compact (R b ∼ 5 × 10 14 cm) and very fast blob located far beyond the BLR radius (to avoid absorption), responsible for the rapidly varying high energy flux. However the long term (days-weeks) coherent evolution of the GeV flux recorded by LAT indicates that there could be also the substantial contribution from another, larger, emission region. We model the spectral energy distribution of PKS 1222+216 during the epoch of the MAGIC detection assuming three different scenarios, namely: (1) a one-zone model considering only the emission from a compact blob outside the BLR; (2) a two-zone model considering the compact blob plus an emitting region encompassing the whole jet cross-section located outside the BLR and ( 3) a two zone model with the jet emitting region inside the BLR. We find that in all cases the high-energy emission from the compact blob is dominated by the inverse Compton scattering of the IR thermal radiation of the dusty torus. Furthermore, both regions are matter dominated, with the Poynting flux providing a negligible contribution to the total jet power. These results disfavor models in which the compact blob is the result of reconnection events inside the jet or "needles" of high-energy electrons accelerated close to the BH. Instead, the observational framework and our radiative models could be compatible with scenarios in which the jet is re-collimated and focussed at large distances from the central BH.

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Section: Introductionmentioning

confidence: 99%

On the origin of theγ-ray emission from the flaring blazar PKS 1222+216

Tavecchio

González

Ghisellini

et al. 2011

A&A

164

196

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“…Since the discovery of the blazar Mrk 421 in the VHE regime (Punch et al 1992), many new detections of AGNs by different experiments have been reported (see, e.g. Horns 2008;Hinton & Hofmann 2009, for reviews). Strong flux variations on different timescales were observed from many AGNs.…”

Section: Introductionmentioning

confidence: 99%

Long-term lightcurves from combined unified very high energyγ-ray data

Tluczykont

Bernardini²,

Satalecka³

et al. 2010

A&A

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Context. Very high-energy (VHE, E > 100 GeV) γ-ray data are a valuable input for multi-wavelength and multi-messenger (e.g. combination with neutrino data) studies. Aims. We aim at the conservation and homogenization of historical, current, and future VHE γ-ray-data on active galactic nuclei (AGN). Methods. We have collected lightcurve data taken by major VHE experiments since 1991 and combined them into long-term lightcurves for several AGN, and now provide our collected datasets for further use. Due to the lack of common data formats in VHE γ-ray astronomy, we have defined relevant datafields to be stored in standard data formats. The time variability of the combined VHE lightcurve data was investigated, and correlation with archival X-ray data collected by RXTE/ASM tested.Results. The combination of data on the prominent blazar Mrk 421 from different experiments yields a lightcurve spanning more than a decade. From this combined dataset we derive an integral baseline flux from Mrk 421 that must be lower than 33% of the Crab Nebula flux above 1 TeV. The analysis of the time variability yields log-normal flux variations in the VHE-data on Mrk 421. Conclusions. Existing VHE data contain valuable information concerning the variability of AGN and can be an important ingredient for multi-wavelength or multi-messenger studies. In the future, upcoming and planned experiments will provide more data from many transient objects, and the interaction of VHE astronomy with classical astronomy will intensify. In this context a unified and exchangeable data format will become increasingly important.

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“…By extrapolating measured energy fluxes [ 76] at TeV energies (e.g. [79,80]) assuming a spectral index of E −2 this flux would have been detected with more than 5σ significance, even after penalizing for the large number of trials. Furthermore, making conservative assumptions for median exposure targets one can exclude a photon flux greater than 1.44 eV cm −2 s −1 with 5σ significance.…”

Section: (Left)mentioning

confidence: 99%

Report from the Multi-Messenger Working Group at UHECR-2014 Conference

Karg¹,

Álvarez-Muñiz

Kuempel

et al. 2016

Proceedings of International Symposium for Ultra-High Energy Cosmic Rays (UHECR2014)

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The IceCube, Pierre Auger and Telescope Array Collaborations have recently reported results on neutral particles (neutrons, photons and neutrinos) which complement the measurements on charged primary cosmic rays at ultra-high energy. The complementarity between these messengers and between their detections are outlined. The current status of their search is reviewed and a cross-correlation analysis between the available results is performed. The expectations for photon and neutrino detections in the near future are also presented.

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Teraelectronvolt Astronomy

Cited by 318 publications

References 145 publications

On the origin of theγ-ray emission from the flaring blazar PKS 1222+216

On the origin of theγ-ray emission from the flaring blazar PKS 1222+216

Long-term lightcurves from combined unified very high energyγ-ray data

Report from the Multi-Messenger Working Group at UHECR-2014 Conference

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