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

MAGIC Collaboration, , , T. Hovatta

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Extreme high-frequency BL Lacs (EHBL) feature their synchrotron peak of the broad-band spectral energy distribution (SED) at vs ≥ 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 γ -ray telescope FACT during a high γ -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) γ -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 γ -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 γ -ray band is 2.04 ± 0.12stat ± 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.

Original languageEnglish
Pages (from-to)3912-3928
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume496
Issue number3
DOIs
Publication statusPublished - 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • galaxies: active
  • BL Lacertae objects: individual: 1ES 2344+514
  • gamma-rays: galaxies
  • GAMMA-RAY EMISSION
  • OBSERVATORY SUPERNOVA SEARCH
  • SPECTRAL VARIABILITY
  • OBJECTS
  • CONNECTION
  • TELESCOPE
  • DISCOVERY
  • RADIATION
  • GALAXIES
  • MODELS

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