Abstract:The BL Lacertae object 3C 66A was detected in a flaring state by the Fermi Large Area Telescope (LAT) and VERITAS in 2008 October. In addition to these gamma-ray observations, F-GAMMA, GASP-WEBT, PAIRITEL, MDM, ATOM, Swift, and Chandra provided radio to X-ray coverage. The available light curves show variability and, in particular, correlated flares are observed in the optical and Fermi-LAT gamma-ray band. The resulting spectral energy distribution can be well fitted using standard leptonic models with and wit… Show more
“…The light curve of 1FHL J0222.6+4302 (3C 66A) displays two prominent flares. The first flare occurred in 2008 October and was detected in the VHE band by VERITAS (Swordy 2008;Abdo et al 2011b (Donato 2010). The third flare is the brightest detected by the Bayesian Block analysis and occurred on 2010 May 25 when three γ rays (above 10 GeV) were detected within a ten hour span.…”
Section: Basic Properties Of the 1fhl Sourcesmentioning
We present a catalog of γ -ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 yr of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of >10 GeV sources (1FHL) has 514 sources. For each source we present location, spectrum, a measure of variability, and associations with cataloged sources at other wavelengths. We found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, we find 20 (12) to have significant pulsations in the range >10 GeV (>25 GeV). In this work we also report that, at energies above 10 GeV, unresolved sources account for 27% ± 8% of the isotropic γ -ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. We also highlight the subset of the 1FHL sources that are best candidates for detection at energies above 50-100 GeV with current and future ground-based γ -ray observatories.
“…The light curve of 1FHL J0222.6+4302 (3C 66A) displays two prominent flares. The first flare occurred in 2008 October and was detected in the VHE band by VERITAS (Swordy 2008;Abdo et al 2011b (Donato 2010). The third flare is the brightest detected by the Bayesian Block analysis and occurred on 2010 May 25 when three γ rays (above 10 GeV) were detected within a ten hour span.…”
Section: Basic Properties Of the 1fhl Sourcesmentioning
We present a catalog of γ -ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 yr of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of >10 GeV sources (1FHL) has 514 sources. For each source we present location, spectrum, a measure of variability, and associations with cataloged sources at other wavelengths. We found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, we find 20 (12) to have significant pulsations in the range >10 GeV (>25 GeV). In this work we also report that, at energies above 10 GeV, unresolved sources account for 27% ± 8% of the isotropic γ -ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. We also highlight the subset of the 1FHL sources that are best candidates for detection at energies above 50-100 GeV with current and future ground-based γ -ray observatories.
“…The blazar 3C 66A shows a variable VHE signal, as seen with VERITAS (Acciari et al 2009;Abdo et al 2011), with a 6% Crab flux flaring episode. Fermi-LAT collaboration reported a significant GeV γ -ray excess from the source.…”
Section: Broadband Spectra Of 1es 0229+200 and 3c 66amentioning
confidence: 87%
“…To demonstrate the potential of the proposed model for the explanation of very hard intrinsic γ -ray spectra, we focused on two distant objects, namely, 1ES 0229+200 (z = 0.1396) and 3C 66A (z = 0.444, though this value is debated; see, e.g., Abdo et al 2011). These two BL Lac objects have different γ -ray properties.…”
Section: Broadband Spectra Of 1es 0229+200 and 3c 66amentioning
confidence: 99%
“…Fermi-LAT collaboration reported a significant GeV γ -ray excess from the source. Moreover, an increase of the GeV flux simultaneously with the VHE flare was observed (Abdo et al 2011). Importantly, the GeV flux level significantly exceeds the de-absorbed VHE flux; thus a smooth connection of these two radiation components with a single emission seems difficult to achieve, for the assumed redshift z = 0.444.…”
Section: Broadband Spectra Of 1es 0229+200 and 3c 66amentioning
We study the applicability of the idea of internal absorption of γ -rays produced through synchrotron radiation of ultrarelativistic protons in highly magnetized blobs to 1ES 0229+200 and 3C 66A, the two TeV blazars which show unusually hard intrinsic γ -ray spectra after being corrected for the intergalactic absorption. We show that for certain combinations of reasonable model parameters, even with quite modest energy requirements, the scenario allows a self-consistent explanation of the non-thermal emission of these objects in the keV, GeV, and TeV energy bands.
“…Medicina and Noto data have contributed to more than 25 refereed publications (e.g. [1,2,3,4,5,28,29,30,16,17,18,19,20,10,11,26,27]. Since 2008 the monitoring is one of the IRA-INAF key science programs.…”
Section: Current Status Of the Monitoringmentioning
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