An intermittent extreme BL Lac: MWL study of 1ES 2344+514 in an enhanced state

Extreme high-frequency BL Lacs (EHBL) feature their synchrotron peak of the broad-band spectral energy distribution (SED) at nu(s) >= 10(17) Hz. The BL Lac object 1ES 2344+514 was included in the EHBL family because of its impressive shift of the synchrotron peak in 1996. During the following years, the source appeared to be in a low state without showing any extreme behaviours. In 2016 August, 1ES 2344+514 was detected with the groundbased gamma-ray telescope FACT during a high gamma-ray state, triggering multiwavelength (MWL) observations. We studied the MWL light curves of 1ES 2344+514 during the 2016 flaring state, using data from radio to very-high-energy (VHE) gamma-rays taken with OVRO, KAIT, KVA, NOT, some telescopes of the GASP-WEBT collaboration at the Teide, Crimean, and St. Petersburg observatories, Swift-UVOT, Swift-XRT, Fermi-LAT, FACT, and MAGIC. With simultaneous observations of the flare, we built the broad-band SED and studied it in the framework of a leptonic and a hadronic model. The VHE gamma-ray observations show a flux level of 55 per cent of the Crab Nebula flux above 300 GeV, similar to the historical maximum of 1995. The combination of MAGIC and Fermi-LAT spectra provides an unprecedented characterization of the inverse-Compton peak for this object during a flaring episode. The Gamma index of the intrinsic spectrum in the VHE gamma-ray band is 2.04 +/- 0.12(stat) +/- 0.15(sys). We find the source in an extreme state with a shift of the position of the synchrotron peak to frequencies above or equal to 1018 Hz

“Não tem corpo, não tem crime”: notas socioantropológicas sobre o ato de fazer desaparecer corpos

O artigo propõe uma análise sócio-antropológica sobre o fenômeno do desaparecimento de pessoas. A reflexão é construída a partir do diálogo com o trabalho de outros pesquisadores e com base em material levantado em meu próprio trabalho de campo, que inclui, o acompanhamento de coletivos de familiares de vítimas de violência, entrevistas, documentação jornalística, estatísticas criminais, legislação sobre o assunto e boletins de ocorrência. Em meio ao emaranhado de atores e enunciados que constroem o desaparecimento enquanto problema policial, familiar e assistencial, interrogo sobre as possíveis relações entre desaparecimentos e homicídios. Argumento que o ato de fazer desaparecer corpos – enquanto prática-evento – fornece um denominador comum para policiais, milicianos e traficantes, atores que ora colaboram entre si, ora disputam. Corpos e pessoas desaparecidas fazem parte da linguagem do confronto, podendo inclusive ser objeto de transação. O desaparecimento forçado corresponde a um dispositivo de força situado entre a violência estatal e a violência criminal

Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and gamma-ray activity in 2015–2016

Abstract We report a characterization of the multiband flux variability and correlations of the nearby (z = 0.031) blazar Markarian 421 (Mrk 421) using data from Metsähovi, Swift, Fermi-LAT, MAGIC, FACT, and other collaborations and instruments from 2014 November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F> 1 TeV < 1.7 × 10⁻¹² ph cm⁻² s⁻¹) and in the 2–10 keV (X-ray) band (F2–10 keV < 3.6 × 10⁻¹¹ erg cm⁻² s⁻¹), during which the Swift-BAT data suggest an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very high-energy (E > 0.1 TeV) gamma-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our data set with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of $43_{-6}^{+9}$ d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process

An intermittent extreme BL Lac: MWL study of 1ES 2344+514 in an enhanced state

Extreme high-frequency BL Lacs (EHBL) feature their synchrotron peak of the broad-band spectral energy distribution (SED) at vs 65 1017 Hz. The BL Lac object 1ES 2344+514 was included in the EHBL family because of its impressive shift of the synchrotron peak in 1996. During the following years, the source appeared to be in a low state without showing any extreme behaviours. In 2016 August, 1ES 2344+514 was detected with the groundbased \u3b3 -ray telescope FACT during a high \u3b3 -ray state, triggering multiwavelength (MWL) observations. We studied the MWL light curves of 1ES 2344+514 during the 2016 flaring state, using data from radio to very-high-energy (VHE) \u3b3 -rays taken with OVRO, KAIT, KVA, NOT, some telescopes of the GASP-WEBT collaboration at the Teide, Crimean, and St. Petersburg observatories, Swift-UVOT, Swift-XRT, Fermi-LAT, FACT, and MAGIC. With simultaneous observations of the flare, we built the broad-band SED and studied it in the framework of a leptonic and a hadronic model. The VHE \u3b3 -ray observations show a flux level of 55 per cent of the Crab Nebula flux above 300 GeV, similar to the historical maximum of 1995. The combination of MAGIC and Fermi-LAT spectra provides an unprecedented characterization of the inverse-Compton peak for this object during a flaring episode. The _ index of the intrinsic spectrum in the VHE \u3b3 -ray band is 2.04 \ub1 0.12stat \ub1 0.15sys.We find the source in an extreme state with a shift of the position of the synchrotron peak to frequencies above or equal to 1018 Hz