Articles written in Journal of Astrophysics and Astronomy
Volume 32 Issue 1-2 March 2011 pp 169-172 Part 3. Blazar Observations in High Energy Bands
The Fermi LAT provides a continuous and uniform monitoring of the Universe in the gamma-ray band. During the first year many gamma-ray blazar flares, some unidentified transients and emission by the Sun while in a quiet state were promptly detected. This is mainly due to the design of the mission, featuring a detector, the LAT with a wide field of view, and to the operation of the spacecraft itself, that can cover every region of the sky every 3 hours. Nevertheless, the scientific exploitation of this monitoring is more fruitful when early information about transients reaches a broader community. In this respect, the indefatigable activity of flare advocates, who worked on weekly shifts to validate the results and quickly broadcast information about flares and new detections, was the key to most scientific results.
Volume 35 Issue 3 September 2014 pp 231-235 Part II: Blazar Observations in Infrared and Optical
The most identified sources observed by Fermi/LAT are blazars, based on which we can investigate the emission mechanisms and beaming effect in the 𝛾-ray bands for blazars. Here, we used the compiled around 450 Fermi blazars with the available X-ray observations to estimate their Doppler factors and compared them with the integral 𝛾-ray luminosity in the range of 1–100 GeV. It is interesting that the integral 𝛾-ray luminosity is closely correlated with the estimated Doppler factor, log 𝑣𝛾 𝐿𝑣𝛾 = (2.95 ± 0.09) log 𝛿 + 43.59 ± 0.08 for the whole sample. When the dependence of the correlation between them and the X-ray luminosity is removed, the correlation is still strong, which suggests that the 𝛾-ray emissions are strongly beamed.
Volume 35 Issue 3 September 2014 pp 373-378 Part IV: Emission Models and Theory
In the first 3.5 years of operations, Fermi detected several sources whose flaring activity brought them to exceed daily fluxes brighter than 𝐹(𝐸 > 100MeV) > 10-6 ph cm-2 s-1. These episodes were promptly reported to the scientific community by the Fermi collaboration by means of astronomer telegrams (ATels). We focus our attention on the sample composed by these flaring sources, most of which are blazars, known to be extremely variable over the whole electromagnetic spectrum, from radio to 𝛾-ray energies. We study properties of the selected sample and compare them to general characteristics of the Fermi source catalogue.
Volume 40 | Issue 5
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