English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present a detailed characterisation and theoretical interpretation of thebroadband emission of the paradigmatic TeV blazar Mrk 421, with special focuson the multi-band flux correlations. The dataset has been collected through anextensive multiwavelength campaign organised between 2016 December and 2017June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT,OVRO, Medicina and Mets\"ahovi. Additionally, four deep exposures (severalhours long) with simultaneous MAGIC and NuSTAR observations allowed a precisemeasurement of the falling segments of the two spectral components. Thevery-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positivelycorrelated at zero time lag, but the strength and characteristics of thecorrelation change substantially across the various energy bands probed. TheVHE versus X-ray fluxes follow different patterns, partly due to substantialchanges in the Compton dominance during a few days without a simultaneousincrease in the X-ray flux (i.e. orphan gamma-ray activity). Studying thebroadband spectral energy distribution (SED) during the days including NuSTARobservations, we show that these changes can be explained within a one-zoneleptonic model with a blob that increases its size over time. Our multi-bandcorrelation study also hints at an anti-correlation between UV/optical andX-ray at a significance higher than 3 sigmas. A VHE flare observed on 2017February 4 shows gamma-ray variability on multi-hour timescales, with a factor10 increase in the TeV flux but only a moderate increase in the keV flux. Therelated broadband SED is better described by a two-zone leptonic scenariorather than by a one-zone scenario. We find that the flare can be produced bythe appearance of a compact second blob populated by high energetic electronsspanning a narrow range of Lorentz factors.

Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017